Agile Data Warehousing Service User Guide Page #1 Agile Data Warehousing Service User Guide Document publish date: 06/04/15 Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #2 Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. PROPRIETARY AND CONFIDENTIAL INFORMATION. This document may not be disclosed to any third party, reproduced, modified or distributed without the prior written permission of GoodData Corporation. GOODDATA CORPORATION PROVIDES THIS DOCUMENTATION AS-IS AND WITHOUT WARRANTY, AND TO THE MAXIMUM EXTENT PERMITTED, GOODDATA CORPORATION DISCLAIMS ALL IMPLIED WARRANTIES, INCLUDING WITHOUT LIMITATION THE IMPLIED WARRANTIES OF MERCHANTABILITY, NON-INFRINGEMENT AND FITNESS FOR A PARTICULAR PURPOSE. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #3 Table of Contents Table of Contents 3 Getting Started with Data Warehouse 8 Data Warehouse and Vertica 9 Project Hierarchy 9 Key Terminology 9 Data Warehouse Quick Start Guide 12 Prerequisites 12 Creating a Data Warehouse Instance 12 Reviewing Your Data Warehouse Instances 15 Connecting to Data Warehouse from CloudConnect 17 Connecting to Data Warehouse from a SQL Client Tool 18 Deprovision Your Data Warehouse Instance 19 Data Warehouse Management Guide 20 Managing your Data Warehouse Instances 20 Data Warehouse Instance Details Page 20 Managing Users and Access Rights 22 Data Warehouse User Roles 22 Adding a User in Data Warehouse 23 Getting a List of Data Warehouse Users 26 Data Warehouse User Details 28 Changing a User Role in the Data Warehouse Instance 28 Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #4 Removing a User from Data Warehouse 29 Resource Limitations 30 Data Warehouse Backups 30 Data Warehouse Developer Guide 32 Data Warehouse System Architecture Overview 32 Data Warehouse and the GoodData Platform Data Flow 32 Data Warehouse Architecture 33 Data Warehouse Technology 35 Column Storage and Compression in Data Warehouse 35 Data Warehouse Logical and Physical Model 36 Intended Usage for Data Warehouse 38 Working with Data Warehouse from CloudConnect 38 Creating a Connection between CloudConnect and Data Warehouse Loading Data through CloudConnect to Data Warehouse 38 41 Project Parameters for Data Warehouse 42 Creating Tables in Data Warehouse from CloudConnect 42 Loading Data to Data Warehouse Staging Tables through CloudConnect 44 Merging Data from Data Warehouse Staging Tables to Production 46 Exporting Data from Data Warehouse using CloudConnect 48 Connecting to Data Warehouse from SQL Client Tools Download the JDBC Driver Data Warehouse Driver Version Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. 50 51 51 Agile Data Warehousing Service User Guide Page #5 Prepare the JDBC connection string 52 Access Data Warehouse From SQuirrel SQL 53 Connecting to Data Warehouse from Java 57 Connecting to Data Warehouse from JRuby 57 Install JRuby 57 Access Data Warehouse using the Sequel library 58 Installing database connectivity to Ruby 59 Installing the Data Warehouse JRuby support 59 Example Ruby code for Data Warehouse 59 Database Schema Design Logical Schema Design - tables and views 60 61 Primary and Foreign Keys 61 Altering Logical Schema 62 Physical Schema Design - projections 62 Columns Encoding and Compression 63 Columns Sort Order 64 Segmentation 64 Configuring the initial superprojection with CREATE TABLE command 65 Creating a New Projection with CREATE PROJECTION command 66 Changing Physical Schema 68 Loading Data into Data Warehouse 69 Loading Compressed Data Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. 71 Agile Data Warehousing Service User Guide Page #6 Use RFC 4180 Compliant CSV files for upload 71 Error Handling 72 Merging Data Using Staging Tables 73 Statistics Collection 74 Querying Data Warehouse 76 Performance Tips 77 Do Not Overnormalize Your Schema 77 Use Run Length Encoding (RLE) 78 Use the EXPLAIN Keyword 78 Use Monitoring Tables 78 Write Large Data Updates Directly to Disk 80 Avoid Unnecessary UPDATEs 81 General Projection Design Tips 81 Minimize Network Joins 82 Choose Projection Sorting Criteria 85 Limitations and Differences in Data Warehouse from Other RDBMS 87 Single Schema per Data Warehouse Instance 87 No Vertica Admin Access 87 Use COPY FROM LOCAL to Load Data 88 Limited Parameters of the COPY Command 88 Limited Access to System Tables 89 Limited Access to System Functions 92 Reserved Entity Names 93 Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #7 Database Designer Tool not available 93 JDBC Driver Limitations 93 Data Warehouse API Reference Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. 100 Agile Data Warehousing Service User Guide Page #8 Getting Started with Data Warehouse GoodData Agile Data Warehousing Service (Data Warehouse) is a fully managed, columnar data warehousing service for the GoodData platform. l Agile Data Warehousing Service may be known to some customers by its former name, Data Storage Service. See A Note about Names. Data Warehouse is designed for storage of the full history of your business data and for easy and quick data extracts. Using standard technologies, you can quickly deliver Data Warehouse data into information marts (such as GoodData projects) or other information delivery systems. In this cloud-based service, Data Warehouse instances can be provisioned and managed through scripts or through the GoodData gray pages. l l l For more information about managing your instance, see Data Warehouse Management Guide. For more information about the GoodData APIs, see GoodData API Documentation. The gray pages are a simple web wrapper over the GoodData APIs. For more information, see https://developer.gooddata.com/article/accessinggray-pages-for-a-project. Using a provided JDBC driver and SQL queries, a developer may interact with a created Data Warehouse instance through CloudConnect Designer or a locally installed SQL client tool. l A default schema is created for you when an instance is created. For more information on accessing Data Warehouse, best practices for schema design, and loading and extracting data, see Data Warehouse Developer Guide. A Note about Names: Some customers may be familiar with Data Warehouse under its former name, Data Storage Service. This document may contain references to "Data Storage Service" or "DSS". Most of these references occur in code snippets, which have not been updated to the new name. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #9 Data Warehouse and Vertica Data Warehouse is running on top of an HP Vertica backend, which enables developers to use the scalability of Vertica’s distributed massively parallel (MPP) columnar engine and powerful SQL extensions. Version in Use: HP Vertica 6.1. Project Hierarchy Your projects are organized into dashboards, dashboard tabs, reports, and the metrics that are contained within those reports. At the lowest level, facts, attributes, and source data represent the foundational components that are aggregated to form the metrics displayed in dashboard reports. Figure: Project Hierarchy Key Terminology Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #10 Term Definition Data Raw records that are loaded into project 1, IBM, $50000, data sets for use in the project’s data 10/10/2012 model. Facts Individual numerical measurements attached to each data set in the source data. Facts are always numbers and are the smallest units of data. Attributes Descriptors used to break apart metrics and provide context to report data. Attributes dictate how metrics are calculated and represented. Attributes may be text (e.g. region) or numerical (e.g. size) data. Examples Opportunity amount (i.e. $25,000) Campaign clicks (i.e. 212); Website views (i.e. 4,508) (by) month; (by) store; (by) employee; (by) region; (by) department Metrics Aggregations of facts or counts of distinct attribute values, which are represented as numbers in reports. Metrics are defined by customizable aggregation formulas. Metrics represent what is being measured in a report. Reports sum of sales; average salary; total costs; count of Opportunity (attribute) Visualizations of data that fall into one of A table showing three categories: tables, charts, and employee salaries headline reports. (metric) broken down by quarter (attribute) All reports contain at least one metric (what is being measured), and often A line graph showing contain one or more attributes (dictating revenue (metric) how that metric is broken down). generated across each month in the past year (attribute) Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #11 A bar graph showing sales figures (metric) broken down by region (attribute) Dashboard Tabs The pages in the GoodData Portal in which reports (either tables or charts) and other dashboard elements (lines, embedded content from the web, widgets, and filters) are displayed. ROI Funnel/Goals Dashboard tabs are typically used to organize reports within a given dashboard. Dashboards Groups of one or more dashboard tabs that contain reports belonging to a common category of interest. From Leads to Won Deals Projects Sales Management A set of dashboards and the users who have permission to interact with them. A project also includes the underlying dashboard, tabs, reports, metrics, and data models. (marketing dashboard) Leads to Cash Subscription Management Projects are often provisioned for use by an entire team or department. In these cases, a change made by one user is visible to all. Data Set A collection of related facts and attributes typically provided from a single data source. An Opportunity data set, containing facts related to attributes like Name, Opportunity Amount, and Stage. Logical Data Model (LDM) A model of the definition of all facts, attributes, and datasets in a project, as well as the relationships between them. To see an example, click Model in the Manage page of the GoodData Portal. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #12 Data Warehouse Quick Start Guide Prerequisites To get started using Agile Data Warehousing Service, please verify that you have the following in place: 1. A GoodData platform account. If you are already accessing the GoodData Portal, you need these credentials in your Data Warehouse implementation. 2. Data Warehouse-enabled authorization token. Your existing project authorization token must be enhanced by GoodData Customer Support to enable the creation and management of your Data Warehouse instances. 3. Application access. This Quick Start Guide covers Java-based graphical database client tools such as SQuirrel SQL and GoodData’s CloudConnect Designer application. You can also connect to Data Warehouse programmatically from Java, JRuby, or other Java-based languages and platforms. 4. (Optional) GoodData project as a target. If you plan to load the data from Data Warehouse into the GoodData platform, you must have the Administrator role for at least one GoodData project. For more information on GoodData projects, see Project Hierarchy. Creating a Data Warehouse Instance Use the steps in this section to initialize a new Data Warehouse instance. In most environments, only one Data Warehouse instance is needed. An Data Warehouse instance can receive data from multiple sources and can be used to populate one or more GoodData projects (datamarts), which deliver the information to business users. l You may find it useful to maintain separate instances for development, testing, and production uses. To initialize a new Data Warehouse instance, you must provide the following information: Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide l Name of the Data Warehouse instance l Description (optional) l Authorization token Page #13 NOTE: Your project authorization token must be enabled to create Data Warehouse instances. Please file a request with GoodData Customer Support. Steps: To create your Data Warehouse from the gray pages, please complete the following steps: 1. Login to the GoodData Portal: https://secure.gooddata.com 2. If you are logged in, reload the page, which refreshes your session. 3. Navigate to the following URL: https://secure.gooddata.com/gdc/datawarehouse/instances 4. If you have not logged into the GoodData Portal previously, you must enter your credentials first. Navigate to the above URL after logging in. 5. The gray page for creating an Data Warehouse instance is displayed. Any previously created Data Warehouse instances are displayed above the form. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #14 Figure: Create an Data Warehouse instance 6. Enter the name, description and project authorization token for your instance into the form. Click Create. 7. In rare cases, you may receive the following error message. If so, please refresh the page opened to the GoodData Portal: This server could not verify that you are authorized to access the document requested. Either you supplied the wrong credentials (e.g., bad password), or your browser doesn't understand how to supply the credentials required.Please see Authenticating to the GoodData API for details. 8. The task is queued for execution in the platform. You may use the link in the gray page to query the status of this task. Reload the page until you see the following: Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #15 Figure: Completed task of Data Warehouse instance creation 9. Click the link to access your Data Warehouse instance. See Data Warehouse Instance Details Page. A default schema is created for you in the new instance. Reviewing Your Data Warehouse Instances After you have created Data Warehouse instances, you may access them through the gray pages: https://secure.gooddata.com/gdc/datawarehouse/instances Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #16 Figure: List of Data Warehouse Instances Each Data Warehouse record includes basic information, including links to the Data Warehouse Detail page for the instance and to a page for managing users who can access the Data Warehouse. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide l l Page #17 For more information on the Data Warehouse Detail page, see ADS User Details. For more information on managing users, see Managing Users and Access Rights. Data Warehouse Status: The status field identifies the current status of the instance: l ENABLED - available and ready for read-write operations l DELETED - a deleted instance. l ERROR - an instance that failed to be created. Connecting to Data Warehouse from CloudConnect Using the JDBC driver, you can create integrations between CloudConnect Designer and your Data Warehouse instance.Then, using CloudConnect components you can create ETL graphs to load data into your Data Warehouse instance, transform it within the database using SQL, and extract it from Data Warehouse for use in your GoodData projects. l l l CloudConnect Designer is a downloadable application for building ETL graphs and logical data models for your GoodData projects. For more information on CloudConnect Designer, see Developer Tools. To get started building your first GoodData project, see Developer Tools. If you have already installed it, please upgrade CloudConnect Designer to the most recent version of CloudConnect Designer. The driver is provided as part of the upgrade package. Steps: 1. Create CloudConnect connection for your Data Warehouse instance. See Creating a Connection between CloudConnect and Data Warehouse. 2. Your connection must include the appropriate JDBC connection string. See Prepare the JDBC connection string. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #18 3. After the connection is established, you can begin loading data into Data Warehouse from CloudConnect. 4. For your project, you should create project parameters for username, password, and JDBC string. See Project Parameters for Data Warehouse. 5. You can create tables using a CREATE TABLE statement using the DBExecute component. See Creating Tables in Data Warehouse from CloudConnect. NOTE:Data Warehouse does not support upsert operations and does not enforce unique row identifiers at load time. 6. Data is loaded through CloudConnect by using the COPY LOCAL command in the DBExecute component. See Loading Data to Data Warehouse Staging Tables through CloudConnect. 7. When data has been loaded into the staging tables, you can perform any necessary in-database operations. Data can then be merged into your production tables. See Merging Data from Data Warehouse Staging Tables to Production. 8. When data is ready to be moved from Data Warehouse to the datamart, you can extract it using the DBInputTable component and pass the metadata into a GD Dataset Writer component for storage in your GoodData project. See Exporting Data from Data Warehouse using CloudConnect. Connecting to Data Warehouse from a SQL Client Tool Data Warehouse supports connection from Java based SQL client tools such as SQuirrel SQL using the GoodData JDBC driver. To connect, please complete the following steps. Steps: 1. Download and install the JDBC driver. See Download the JDBC Driver. 2. Prepare the connection string. See Prepare the JDBC connection string. 3. Create the connection from your favorite Java-based SQL tool. Example documentation is provided for the following: Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide l Page #19 See Access Data Warehouse From SQuirrel SQL. Deprovision Your Data Warehouse Instance If needed, you can deprovision an Data Warehouse instance. l l When an instance is deleted, it is still listed as one of your Data Warehouse instances. However, its status is marked as DELETED. Deleted instances are still visible through the gray pages. However, data cannot be added to or removed from the instance using the JDBC driver. Deprovisioning an instance removes it from access through the JDBC driver. Before you deprovision an instance, you should review all of the users and projects that are connected to the instance. All users should be informed of the change in advance of removing the instance, so that they can verify that none of their projects is affected. Also, you should make arrangements so that any project using the Data Warehouse instance has access to data through another resource, such as a replacement Data Warehouse instance. Deleting an instance cannot be undone. Steps: 1. Visit your list of instances: https://secure.gooddata.com/gdc/datawarehouse/instances 2. Click the instance you wish to remove. 3. Then, click Delete. 4. The status of the instance is changed: DELETED. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #20 Data Warehouse Management Guide This section provides guidance in how to manage your Data Warehouse instances and the users in those instances through the GoodData gray pages. l The gray pages reflect the structure of the underlying GoodData APIs. The commands you execute through the gray pages can be managed programmatically through the APIs. Data Warehouse users are specific to the instances in which you create them. They are not equivalent to platform users. Managing your Data Warehouse Instances Through the gray pages, you can review your Data Warehouse instances and manage aspects of them. Topics: l Creating an Data Warehouse Instance l Reviewing Your Data Warehouse Instances l Deprovision Your Data Warehouse Instance l Data Warehouse Instance Details Page Data Warehouse Instance Details Page You may access the details of individual Data Warehouse instances through the self links in the List of Data Warehouse Instances or through direct URI: Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #21 Figure: Your created Data Warehouse instance Key URLs: You may wish to retain the following URLs for later use in the gray pages: l l self - The URL to the Data Warehouse instance is used to construct a JDBC connection string required to connect to your Data Warehouse instance using CloudConnect or other Java-based tool. users - URL to list of users in the Data Warehouse instance Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide l Page #22 jdbc - URL to the JDBC access point for the Data Warehouse instance, which is used internally by the JDBC driver to establish a database connection. See Connecting to Data Warehouse from a SQL Client Tool. Managing Users and Access Rights This section provides details on how to manage Data Warehouse users and their permissions within your instance. NOTE: You must have GoodData platform account before you may be added as a new user to an Data Warehouse instance. Topics: l Data Warehouse User Roles l Adding a User in Data Warehouse l Get List of Data Warehouse Users l Data Warehouse User Details l Change a User’s Role in the Data Warehouse Instance l Removing a User from Data Warehouse Data Warehouse User Roles The following roles may be assigned to Data Warehouse users. General permissions are listed for each role: Data Admin role Role identifier: dataAdmin This role should be assigned to any Data Warehouse user who needs to use the instance for loading and processing data. l Read all tables or views. l Import data into Data Warehouse tables. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide l Create, drop or purge Data Warehouse tables. l Create other objects such as functions and views in the database. Page #23 NOTE: The Data Admin role is sufficient for basic use of the Data Warehouse instance. Admin role Role identifier: admin This role should be reserved for the user or users who need to have control over the other users in the Data Warehouse instance. l All permissions of the Data Admin role, plus the following: l Add user. l Remove user. User cannot be the Owner of the instance. l l Change a user’s role. User cannot be the Owner of the instance and cannot be changed to the Owner role. Edit the name or description of an Data Warehouse instance. Data Warehouse instance owner The user who created the Data Warehouse instance is automatically assigned ownership of the instance. Ownership is not a formal role in the instance. NOTE: The Owner of a Data Warehouse instance cannot be changed. The Owner is also automatically assigned the Admin role. The Owner has all of the permissions of the Admin role, as well as the permission to delete the Data Warehouse instance. Adding a User in Data Warehouse Use the following steps to add a user to the Data Warehouse instance via the gray pages. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #24 NOTE: The account creating the new user must be an Admin for the Data Warehouse instance. NOTE: Only users with existing GoodData platform accounts may be added to the Data Warehouse instance. NOTE: Users are added silently. No email is delivered to the user. Steps: 1. Get a list of users to add. For each user, you must acquire either the user profile URI or the GoodData platform account identifier. NOTE: A user’s profile URI is available when the user logs in through the gray pages. You may also query for the list of users in a project via API; the returned JSON includes user profile identifiers for each user in the project. 2. Determine the role to apply to the user. See Data Warehouse User Roles. 3. Acquire the instance identifier for the Data Warehouse instance to which you wish to add the user. See Prepare the JDBC connection string. 4. Visit the following gray page: https://secure.gooddata.com/gdc/datawarehouse/instanc es/[DW_ID]/users 5. The list of users and their roles is displayed. At the bottom of the page, complete the form: Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #25 Figure: Add new Data Warehouse user form 6. From the drop-down, select the Data Warehouse user role to assign to the user. See Data Warehouse User Roles. 7. Enter the Profile URI for the user or the user’s GoodData platform identifier. Do not enter both. NOTE: When adding users by GoodData platform login identifier, you should retrieve and store the profile URI, as other API endpoints may not permit use of the login identifier for entry. 8. To add the user, click Add user to the storage. 9. In rare cases, you may receive the following error message. If so, please refresh the page opened to the GoodData Portal: This server could not verify that you are authorized to access the document requested. Either you supplied the wrong credentials (e.g., bad password), or your browser doesn't understand how to supply the credentials required.Please see Authenticating to the GoodData API for details. 10. The task is queued for execution in the platform. You may use the link in the gray page to query the status of this task. Reload the page until you see the following: Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #26 Figure: User added to Data Warehouse instance 11. The user has been added to the instance. 12. Repeat these steps to add additional users to the Data Warehouse instance. Getting a List of Data Warehouse Users To retrieve the list of users in your Data Warehouse instance, please visit the following URL: https://secure.gooddata.com/gdc/datawarehouse/instances/[DW_ ID]/users NOTE: Admin users can see all users in the Data Warehouse instance. More restricted users can retrieve only information on their own accounts. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #27 Figure: List of Users in an Data Warehouse Instance You may use the form at the bottom of the screen to add users to the Data Warehouse instance. See Adding a User in Data Warehouse. Profile identifiers: profile - This URI provides access to the profile of an user. In the following profile URI: /gdc/account/profile/2374a6d5d45cca7a405d6c690 The profile identifier is the long string at the end of the profile URI. For example in the following URL: Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #28 2374a6d5d45cca7a405d6c690 To review details of the user or to make changes to the user account, click the self link. l See Data Warehouse User Details. Data Warehouse User Details In the Data Warehouse User Details gray page, you can review the profile of the selected user of your Data Warehouse instance. l In the list of Data Warehouse users in your instance, click the self link for the user. Figure: Data Warehouse User Details Page l To verify the username of the Data Warehouse user, click the profile link. l See Change a User Role in the Data Warehouse Instance. l See Removing a User from Data Warehouse. Changing a User Role in the Data Warehouse Instance Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #29 Use the following steps to change the role assigned to a user in your Data Warehouse instance. NOTE: The user applying the change must be an Admin in the instance. NOTE: The owner of the Data Warehouse instance cannot be demoted from an Admin role or removed from the instance. Steps: 1. In the list of Data Warehouse users in your instance, click the self link for the user. The user details are displayed. See Data Warehouse User Details. 2. To verify the user’s identity, click the profile link. 3. From the role drop-down, select the new user role. See Data Warehouse User Roles. 4. Click Update role. 5. The user’s role is updated. Verify the value for role. Removing a User from Data Warehouse Please complete the following steps to remove a selected user from your Data Warehouse instance. NOTE: The user applying the change must an Admin in the instance. NOTE: The owner of the instance cannot be demoted from an Admin role or removed from the instance. Steps: 1. In the list of Data Warehouse users in your instance, click the self link for the user. The user details are displayed. See Data Warehouse User Details. 2. To verify the user’s identity, click the profile link. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #30 3. Click Delete. 4. The user is removed from the instance. Resource Limitations Memory limitations: By default, individual customer queries are not allowed to allocate more than 10 GB of RAM. This limitation may vary depending on your license. For more information, please contact GoodData Account Management. Time limitations: Queries running for longer than 2 hours to execute are terminated. Parallel query limitations: You may execute up to 4 queries in parallel per customer token. l l l If more than 4 queries are executed in parallel, additional queries are queued for running at a later time when resources become available. Resources are checked once per minute. Each query is allocated memory from your shared memory pool, so you may run into the memory limitations even if you are within your query count limitation. If queries are queued for more than two hours, they are terminated. Tip: Where possible, GoodData recommends serializing your queries and staggering jobs to prevent overlap. Data Warehouse Backups GoodData performs standard backups of the Vertica clusters hosting Data Warehouse on a daily basis. In the unlikely event of service disruption or other network-wide failure, data is restored to the previous backup. NOTE: GoodData does not provide on-demand data recovery. Users may manage their own backups through third-party tools. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide This backup policy matches the backup policy provided by the GoodData platform. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Page #31 Agile Data Warehousing Service User Guide Page #32 Data Warehouse Developer Guide Data Warehouse System Architecture Overview This section outlines Agile Data Warehousing Service integration with the GoodData BI platform architecture and data flows, as well as the architecture of Data Warehouse itself. Data Warehouse and the GoodData Platform Data Flow Figure: Data Warehouse and Platform Data Flows Typically, the data flow is the following: 1. Source data may be uploaded by the customer to GoodData’s incoming data storage via WebDAV, where it is collected by the BI automation layer, which is typically custom CloudConnect ETL or Ruby scripts. Source data may also be retrieved directly by the automation layer from the source system’s API. 2. For more information on project-specific storage, see https://developer.gooddata.com/article/project-specific-storage. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #33 3. ETL graphs may be created and published from CloudConnect Designer. For more information on CloudConnect Designer, see Developer Tools. 4. Ruby scripts may be built and deployed using the GoodData Ruby SDK. See http://sdk.gooddata.com/gooddata-ruby/. NOTE: Developers may access Data Warehouse remotely with SQL via the JDBC driver provided by GoodData. Other JDBC drivers cannot be used with Data Warehouse. For more information, see Download the JDBC Driver. 5. The automation layer imports the data into Data Warehouse and does any necessary in-database processing using SQL. See Querying Data Warehouse. 6. At this point, the data is ready for import into a presentation layer. Data is extracted from Data Warehouse using SQL and is typically imported into a GoodData project. 7. During extraction, any additional transformations may be performed in the database using SQL or using CloudConnect Designer before the data is uploaded to the presentation layer. 8. The data is available through the presentation layer for users. For a simple example of a data flow implementation in CloudConnect, see Working with Data Warehouse from CloudConnect. Data Warehouse Architecture Internally, Agile Data Warehousing Service consists of a number of shared or dedicated clusters. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #34 Figure: Agile Data Warehousing Service architecture Each Data Warehouse instance is spread across multiple nodes within either shared clusters or a dedicated cluster. NOTE: Data Warehouse instances are isolated; it is not possible to run a query that references data stored in two different Data Warehouse instances, even if both instances are accessible to the same user. Licensees of the GoodData platform receive an authorization token for creating projects in the platform. After it has been enhanced, this token may also be used to create an Data Warehouse instance, and it ensures that your Data Warehouse instance is created on an appropriate cluster. NOTE: Your project authorization token must be enabled to create Data Warehouse instances. Please file a request with GoodData Customer Support. l See Management Guide. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #35 Data Warehouse Technology Agile Data Warehousing Service is based on the HP Vertica database. Each node in an Data Warehouse cluster runs an instance of the Vertica database. Data Warehouse supports the SQL:99 standard with several Vertica-specific extensions. l l For more information on the limitations against the SQL:99 standard or the Vertica documentation, see Limitations. For additional details, see Vertica documentation. NOTE: You need GoodData’s Data Warehouse JDBC Driver to connect to Data Warehouse. The Vertica JDBC driver cannot be used to connect to Data Warehouse. See Download the JDBC Driver. Column Storage and Compression in Data Warehouse Unlike standard row-based relational databases, the Data Warehouse stores data using a columnar storage mechanism: Figure: Row vs. Column storage Columnar storage is particularly suitable for improve disk performance when retrieving complex analytical queries or running in-database business transformations. Queries can be answered by accessing only the columns required by the query, which fits well with data warehousing and other readintensive use cases. Moreover, the data in columns are compressed using various encoding and compression mechanisms, which further improves the disk I/O. For example, run length encoding can be applied to the “symbol” column: Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #36 Figure: Columnar storage enhances disk storage and access Data Warehouse Logical and Physical Model Schema design elements such as tables and views are considered a database’s logical database model. These objects provide information about available data elements. However, they do not define how the data is actually stored on the disk or how they are distributed across the nodes within an Data Warehouse cluster. Those structures are part of the physical data model. The structures that define how table columns are organized on the disk and how the data are distributed in the cluster are called projections: Figure: Logical model vs. physical model The following parameters of a physical data representation can be configured using a projection: l l l Columns to be included and column encoding (run-length encoding, delta encoding, etc) Sequence of the table columns Segmentation: The rows to keep on the same node and the projections to be replicated instead of split Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #37 A single table may have multiple projections to support different query types. A projection does not have to necessarily include all table columns. For example, in a large transactional table, you may wish to have a projection sorted by timestamp to support queries over the most recent data. You may also need a projection sorted by customer to support a customer segmentation query, which could be expensive. The table would have two additional projections to support these use cases. l l A projection is similar to a materialized view in traditional database. Like a materialized view, a projection stores result sets on disk, instead of recomputing them with each query. As data is added or updated, these results are automatically refreshed. For more information on projections, see Physical Schema. Data Warehouse users create SQL queries against the logical model. The underlying engine automatically selects the appropriate projections. l As a feature of Vertica, Data Warehouse databases lack indexes. In place of indexes, you use optimized projections to optimize queries. Each logical table requires a physical model. This model can be described by a projection for the table that includes all table columns. A projection with all table columns is called a superprojection. l l The CREATE TABLE command automatically creates a superprojection for the new table. Proprietary SQL extensions are available for configuring the parameters of the default superprojection. When building your Data Warehouse database, you can start with one superprojection for each table. You may consider adding additional projections from HP Vertica to improve performance of slow queries. l l Additional projections can be defined using the CREATE PROJECTION command. In addition to specifying the columns in the projection, developers may specify the compression, sort order, and the distribution of data across the nodes of the cluster (segmentation) for the projection. For more information about designing and optimizing the data model: Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide l See Database Schema Design. l See Performance Tips. l Page #38 For additional details, see the Physical Schema section of the Vertica documentation. Intended Usage for Data Warehouse Agile Data Warehousing Service is a relational database designed for data warehousing use cases. Although Data Warehouse may be accessed from any JDBC-capable client application and supports a superset of the SQL:99 specification, Data Warehouse is expected to be used as a data warehouse and persistent staging environment. NOTE: It is not recommended to use Data Warehouse as an OLTP database with a large number of parallel queries and data updates with a very short expected response time. Working with Data Warehouse from CloudConnect The CloudConnect Designer installation package includes the GoodData JDBC driver, which is needed to connect to Agile Data Warehousing Service. l l l CloudConnect Designer is a downloadable application for building ETL graphs and logical data models for your GoodData projects. For more information on CloudConnect Designer, see Developer Tools. To get started building your first GoodData project, see Developer's Getting Started Tutorial. If you have already installed it, please upgrade CloudConnect Designer to the most recent version of CloudConnect Designer. The driver is provided as part of the upgrade package. Creating a Connection between CloudConnect and Data Warehouse Please complete the following to create a connection between CloudConnect and Data Warehouse. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #39 Steps: 1. Open your project’s ETL graph or create a new one. 2. To create a new database connection in CloudConnect using the built-in Data Warehouse driver, secondary-click Connections in the Project Outline. Then select Connections > Create DB Connection.... NOTE: Do not create your connection from the File menu. 3. Select a <custom> database connection. 4. You may wish to use project parameters for the username and password and to pass them into the connection at runtime. See Loading Data through CloudConnect to Data Warehouse. 5. The connection requires a connection string. Remember to insert the identifier for the Data Warehouse instance (DW_ID) as part of the connection string. See Prepare the JDBC connection string. 6. Your CloudConnect connection should look similar to the following: Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #40 Figure: Data Warehouse connection from CloudConnect 7. Click Validate connection to test it. 8. If the connection succeeds, save it. You have configured your graph in CloudConnect to connect to the specified Data Warehouse instance. This connection must be referenced in each component instance that interacts with Data Warehouse. Reusing the connection: The connection to Data Warehouse is local to the graph in which you created it. It must be copied into other graphs to be used in other projects, if project parameters have been created for it. l By default, each database component instance creates a new connection. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #41 NOTE: To avoid repeating yourself, the connection settings should reference CloudConnect variables rather than using hard-coded constants. See Project Parameters for Data Warehouse. NOTE: To create a connection that can be reused by multiple connections, you may deselect the Thread-safe button in the Advanced tab of the Connection Settings dialog. However, this configuration should be avoided unless truly necessary for operations such as retrieving an auto-incremented key. Do not turn off the thread safety for connections used by components expected to issue long-running queries. Transactions running for more than 2 hours will be terminated. Loading Data through CloudConnect to Data Warehouse Using the DBExecute component, you specify the CloudConnect connection to use and the COPY LOCAL commands to execute against your Data Warehouse instance. l If you have not done so already, create a connection in CloudConnect Designer so that the application can interact with Data Warehouse. See Connecting to Data Warehouse from CloudConnect. NOTE: You must use the COPY LOCAL command to load data into Data Warehouse. For more information on the command, supported parameters, and its Data Warehouse-specific implementation, see Loading Data into Data Warehouse. Data Warehouse does not support upsert operations and does not require unique record identifiers at load time. For this reason, you should utilize staging tables to load your data and then to perform a merge. See Merge data using staging tables. Tip: In CloudConnect Designer, you should build the load and merge operations separately. You can validate that the loading Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #42 operation has successfully completed before kicking off the merge operation. Project Parameters for Data Warehouse When you are creating CloudConnect projects, you should parameterize values that may change based on the target GoodData project. For example, if the same basic ETL process is to be used for multiple projects from multiple source systems, you should turn access parameters such as username, password, and access URL into CloudConnect parameters. In your project, you should define the following project parameters: Parameter Description DSS_USER The Data Warehouse user identifier to use to connect DSS_PASSWORD This parameter can be used at runtime to apply a password to connect to Data Warehouse. DSS_JDBC_URL This parameter should be used to define the JDBC URL to access the Data Warehouse project. Creating Tables in Data Warehouse from CloudConnect Before you load data into staging tables, you must create the tables for staging and production. Tip: For organization purposes, it is a recommended practice that you create your table initialization ETL in a separate graph in CloudConnect Designer. In this example, staging tables with the “in_” prefix are created for a dataset called opportunities. Steps: Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #43 1. In the graph, add a DBExecute component. Edit the component. 2. Properties: 1. DB Connection: select the connection you created 2. SQL query: see below. 3. Print statements: true 4. Transaction set: All statements 3. For the SQL query, you must create the staging tables. The example below creates the table for in_opportunities. Note the use of the in_ prefix for the staging environment: CREATE TABLE IF NOT EXISTS in_opportunities ( _oid IDENTITY PRIMARY KEY, id VARCHAR(32), name VARCHAR(255) NOT NULL, created TIMESTAMP NOT NULL, closed TIMESTAMP, stage VARCHAR(32) NOT NULL, is_closed BOOLEAN NOT NULL, is_won BOOLEAN NOT NULL, amount DECIMAL(20,2), last_modified TIMESTAMP ) Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #44 4. Your DBExecute component should look like the following: Figure: Creating staging tables 5. Save your graph. Loading Data to Data Warehouse Staging Tables through CloudConnect Using a separate DbExecute component, you can use the COPY LOCAL command to populate your staging tables with data from a locally referenced file. l l For more information on the COPY LOCAL command, see Loading Data into Data Warehouse. For more information on creating the staging tables, see Creating Tables in Data Warehouse from CloudConnect. In the following example, you create a DbExecute instance to load the staging table for in_opportunities from the local file opportunities.csv. Steps: Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #45 1. In the graph, add a DBExecute component. Edit the component. 2. Properties: 1. DB Connection: select the connection you created 2. SQL query: see below. 3. Print statements: true 4. Transaction set: All statements 3. For the SQL query, you must specify at least two commands in the following order. 4. Before copying into the table, the TRUNCATE command is used to ensure the staging table is empty. 5. The COPY LOCAL commands to copy from the local source file (opportunities.csv in this case) to the staging table you created. 6. Commands are separated by a semicolon. Your SQL might look like the following: TRUNCATE in_opportunities; COPY in_opportunities (id, name, created, closed, stage, is_closed, is_won, amount, last_modified) FROM LOCAL '${DATA_SOURCE_DIR}/opportunities.csv' SKIP 1 ABORT ON ERROR Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #46 7. Your DBExecute component should look like the following: Figure: Loading staging tables 8. Save your graph. Merging Data from Data Warehouse Staging Tables to Production After data has been staged in Data Warehouse, you can use the following basic steps to merge into your production environment. In this case, you create a DBExecute instance to MERGE INTO records from the staging tables. Steps: 1. In the graph, add a DBExecute component. Edit the component. 2. Properties: 1. DB Connection: select the connection you created 2. SQL query: see below. 3. Print statements: true 4. Transaction set: All statements Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #47 3. For the SQL query, you must specify the MERGE INTO commands to merge from staging to production: MERGE INTO opportunities t USING in_opportunities s ON s.id = t.id WHEN MATCHED THEN UPDATE SET name = s.name, created = s.created, closed = s.closed, stage = s.stage, is_closed = s.is_closed, is_won = s.is_won, amount = s.amount WHEN NOT MATCHED THEN INSERT (id, name, created, closed, stage, is_closed, is_ won, amount) VALUES (s.id, s.name, s.created, s.closed, s.stage, s.is_closed, s.is_won, s.amount) 4. Your DBExecute component should look like the following: Figure: Merging into Production Save your graph. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #48 After this graph is executed, you may truncate the staging tables. Exporting Data from Data Warehouse using CloudConnect To export data from Data Warehouse using CloudConnect, you deploy the DBInputTable component to extract data from your production tables. This component can be connected to a Writer component to store the data in its new destination. Typically, this component is the GD Dataset Writer component, which writes the data to a specified GoodData project. Steps: 1. Add the DBInputTable component. Edit it. 2. Properties: 1. DB Connection: select the connection you created 2. SQL query: see below. 3. Data policy: Strict is recommended. 4. Print statements: false 3. For the SQL query, you must specify the SELECT command to retrieve the data from the production table. In the SQL Query Editor, the fields in the query must be mapped to the output metadata fields for consumption by the next component in the graph: Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #49 Figure: SQL Query for exporting data tables Tip: You should specify manually each field in the table that you are extracting. If the table schema changes in the future, then the ETL process continues to function, as long as the change does not include modifications to the source fields. Avoid using SELECT *. 4. Click OK. 5. The data that is extracted is mapped to the metadata of the DBInputTable component. 6. To write to a GoodData project, add a GD Dataset Writer component. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #50 7. Create an edge between the two components. 8. In the GD Dataset Writer component, specify the GoodData project identifier, the target dataset, and the field mappings from DBInputTable metadata to dataset fields. 9. Save your graph. Your graph should look like the following: Figure: Final export graph Connecting to Data Warehouse from SQL Client Tools This section describes how to connect to Data Warehouse from SQL clients using JDBC. NOTE: CloudConnect Designer is pre-packaged with the JDBC driver and automatically receives any updates if the driver is updated. Downloading and installing it in CloudConnect Designer is not necessary. See Working with Data Warehouse from CloudConnect. There are many free and commercial SQL client tools. Feel free to use your preferred tool, as the set up is consistent. Steps: These are the basic steps: 1. Download the Data Warehouse JDBC driver. See Download the JDBC Driver. 2. Add the Data Warehouse JDBC driver into your tool. For more information, please consult the production documentation provided with your SQL client tool. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #51 3. Build your Data Warehouse instance’s JDBC connection string. See Prepare the JDBC connection string. 4. Use the Data Warehouse driver and JDBC connection string to set up a connection. 5. You may be also asked for the driver class name: com.gooddata.dss.jdbc.driver.DssDriver l For additional details, see Access Data Warehouse From SQuirrel SQL. Download the JDBC Driver Connection to Data Warehouse is supported only by using the JDBC driver provided by GoodData. This driver enables Data Warehouse connectivity from: l CloudConnect ETL Designer NOTE: The driver is pre-installed in supporting versions of CloudConnect Designer. l Java-based visual SQL client tools l Java programming environment, such as JRuby NOTE: For third-party SQL client tools, the driver is available at the following URL: https://developer.gooddata.com/downloads/dss/ ads-driver.zip To download the JDBC driver, click Developer Tools. Data Warehouse Driver Version If you have having issues with your Data Warehouse connection, you may be asked by GoodData Customer Support to provide the version number of the JDBC driver that you are using for Data Warehouse. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #52 NOTE: You cannot use a Vertica JDBC driver for Data Warehouse. You must use the Data Warehouse driver provided by GoodData. To acquire the Data Warehouse driver version: l l l l An updated version of CloudConnect Designer always contains the latest version of the Data Warehouse driver. CloudConnect enables automatic updates of the application. If you have downloaded the driver from the Developer Portal, you can locate the driver version through one of the following methods: When the ZIP file is unzipped, the driver version number is embedded in the filename. If you no longer have the ZIP file, the version number can be retrieved through standard method calls on the Data Warehouse driver. Use: Driver.getMajorVersion() & Driver.getMinorVersion() DatabaseMetaData.getDriverMinorVersion() & DatabaseMetaData.getDriverMajorVersion() DatabaseMetaData.getDriverVersion() For more information, please visit GoodData Customer Support. Prepare the JDBC connection string Also known as the JDBC URL, the JDBC connection string instructs Java-based database tools how to connect to a remote database. For Data Warehouse, the format of the JDBC connection string is the following: Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #53 jdbc:gdc:datawarehouse://secure.gooddata.com/gdc/datawarehous e/instances/[DW_ID] To acquire your DW_ID: 1. Review your Data Warehouse instances at the following URL: https://secure.gooddata.com/gdc/datawarehouse/instances 2. For the Data Warehouse instance to use, click the self link. 3. Copy the last part of the URL: Figure: Data Warehouse Instance ID Suppose your Data Warehouse instance URL was the following: https://secure.gooddata.com/gdc/datawarehouse/instances/ Your JDBC connection string is the following: jdbc:gdc:datawarehouse://secure.gooddata.com/gdc/datawarehous e/instances/ This connection string must be applied in CloudConnect Designer or the database tool of your choice. l Working with Data Warehouse from CloudConnect l Access Data Warehouse From SQuirrel SQL Access Data Warehouse From SQuirrel SQL Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #54 SQuirrel SQL is a powerful, open-source JDBC database interface. For more information, see http://squirrel-sql.sourceforge.net/. Steps: To connect from SQuirrel SQL to your instance, please complete the following steps. 1. If you have not done so already, download and install the JDBC driver. See Download the JDBC Driver. 2. Download and install SQuirrelSQL. See http://squirrelsql.sourceforge.net/#installation. 3. Launch the application. Select File > New Session Properties. 4. To add the JDBC driver, select Drivers > New Driver. 5. Properties: 1. Name: Enter something like GoodData Data Warehouse JDBC. 2. Example URL: Use the following: jdbc:gdc:datawarehouse://secure.gooddata.com/gdc/ datawarehouse/instances/[Data Warehouse_ID] 3. Website URL: (optional) You may enter: https://developer.gooddata.com 4. Click the Extra Class Path tab. Click Add. Navigate your local hard drive to locate the JDBC driver you downloaded. 5. For the Class Name, enter the following value: com.gooddata.dss.jdbc.driver.DssDriver Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #55 6. The configuration for your new driver should look like the following: Figure: New JDBC driver for SQuirreLSQL 7. Click OK. 8. A success message indicates that the driver has been properly installed and registered with the application. 9. In the left navigation bar, click Drivers. Select the GoodData JDBC driver from the list. 10. Create a new database alias for the connection. From the menu, select Aliases > Connect.... Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #56 11. Click the Plus icon. 12. Properties: 1. Name: Suggest GoodData Data Warehouse JDBC. 2. Driver: Select the GoodData JDBC driver that you just created. 3. URL: This value should be modified to be a direct reference to your Data Warehouse instance. The final value of the URL should be the internal identifier of the Data Warehouse instance. See Reviewing Your Data Warehouse Instances. 4. User Name and Password: Specify the GoodData platform account to use to connect to the instance. 13. Your alias should look like the following: Figure: SQuirreLSQL alias for Data Warehouse 14. Click Test to validate the connection. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #57 15. If the connection works, click OK. 16. You are now able to connect to Data Warehouse. Connecting to Data Warehouse from Java You can connect the Data Warehouse from Java using the Data Warehouse JDBC Driver. See Download the JDBC Driver. NOTE: Data Warehouse is designed as a service for building data warehousing solutions, and it is not expected to be used as an OLTP database. To provide Data Warehouse data to your end users, you should push it into either a GoodData project to deliver analytical dashboards or to your operational database, which should be optimized to be a backend of your user-facing application code. For more information on GoodData projects, see Project Hierarchy. Connecting to Data Warehouse from JRuby You may use the following set of instructions to connect to Data Warehouse using Ruby. Install JRuby The driver for connecting to Data Warehouse is available only as a JDBC driver at this time. No native library in Ruby is available. As a result, you must first install JRuby. Steps: 1. Install Ruby. 2. The easiest method is to install using the Ruby Version Manager (RVM). 3. If you don’t have the RVM installed, please visit https://rvm.io/rvm/install. 4. After you have RVM installed, run the following command to install the Java-based implementation of Ruby onto your local machine: Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #58 $ rvm install jruby 5. To switch to the installed version of JRuby: $ rvm use jruby 6. Optionally, to make JRuby your default Ruby environment, use the following command: $rvm --default use jruby l (Optional) To restore the original Ruby system as your default, you may use: $rvm use system 7. To verify your installed version of Ruby, execute the following command: $ ruby -v 8. The output should look like the following: jruby 1.7.9 (1.9.3p392) 2013-12-06 87b108a on Java HotSpot (TM) 64-Bit Server VM 1.6.0_65-b14-462-11M4609 [darwin-x86_ 64] Access Data Warehouse using the Sequel library The Sequel library provides relatively low-level access with nice abstractions and a friendly programming interface, active development, and JDBC support. It has been tested for use with JRuby for purposes of integrating with Data Warehouse. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide l l l Page #59 For more information on the Sequel library, see http://sequel.jeremyevans.net/. For quick start documentation, see http://sequel.jeremyevans.net/rdoc/files/doc/cheat_sheet_rdoc.html. For a complete reference guide, see http://sequel.jeremyevans.net/rdoc/. Installing database connectivity to Ruby Use the following command: $ gem install sequel The Ruby database abstraction layer (Sequel) is installed. Installing the Data Warehouse JRuby support To install Data Warehouse support for JRuby, you must clone a Git repository and perform the following installation. Please execute the following steps in the order listed below. Steps: $ git clone https://github.com/gooddata/gooddata-dss-ruby $ cd jdbc-dss $ rvm use jruby $ rake install Example Ruby code for Data Warehouse The following Ruby script provides a simple example for how to connecting to Data Warehouse using JRuby and then to execute a simple query using Sequel: #!/usr/bin/env ruby require 'rubygems' require 'sequel' require 'jdbc/dss' Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #60 Jdbc::Data Warehouse.load_driver Java.com.gooddata.dss.jdbc.driver.DssDriver # replace with your Data Warehouse instance: dss_jdbc_url = 'jdbc:gdc:datawarehouse://secure.gooddata.com/gdc/datawarehou se/instances/[DW_ID]' # replace with your GoodData platform login name: username = '[email protected]' # replace with your GoodData platform password: password = 'MyPassword' # example query Sequel.connect dss_jdbc_url, :username => username, :password => password do |conn| conn.run "CREATE TABLE IF NOT EXISTS my_first_table (id INT, value VARCHAR(255))" conn.run "INSERT INTO my_first_table (id, value) VALUES (1, 'one')" conn.run "INSERT INTO my_first_table (id, value) VALUES (2, 'two')" conn.fetch "SELECT * FROM my_first_table WHERE id < ?", 3 do |row| puts row end end NOTE: Data Warehouse is designed as a service for building data warehousing solutions and it is not expected to be used as an OLTP database. If you are looking for a way of exposing the data in Data Warehouse to your end users, consider pushing necessary data from Data Warehouse into either a GoodData project to deliver analytical dashboards or to your operational database that is optimized to be a backend of your end user facing application code. Database Schema Design Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #61 Data Warehouse makes a clean distinction between the logical data model, which defines the tables and columns, and the physical data model, which identifies how the data is organized using the columnar storage and distributed across the cluster nodes. Figure: Agile Data Warehousing Service architecture l For more information on differences between the LDM and the PDM, see Data Warehouse Logical and Physical Model. Logical Schema Design - tables and views The logical database schema can be created with a standard CREATE TABLE command. Similarly, views can be created using the CREATE VIEW command. An Data Warehouse view is just a persisted SELECT statement. There is no significant performance difference between querying a derived result set inlined as a sub-select versus persisted as view. l Materialized views are not supported. Primary and Foreign Keys Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #62 Data Warehouse does not enforce the uniqueness of primary keys. However, a non-unique value in a primary key column causes errors in the following situations: l l During the load, if data is loaded into a table that has a pre-joined projection In join queries at query time, if there is not exactly one dimension row that matches each foreign key value. Tip: To ensure the uniqueness of your primary keys, use staging tables and the MERGE command (see Merging Data Using Staging Tables). If you want to store a version history in your table, the identifier of the source entity should be neither declared as a PRIMARY KEY nor referenced by a FOREIGN KEY column. Similarly, the referential integrity declared by a foreign key constraint is not enforced during the data load, unless there is a pre-join projection. However, it may result in a constraint validation error later if a join query is processed or a new pre-join projection is created. Altering Logical Schema Data Warehouse supports table modification via the standard ALTER TABLE command. The underlying columnar storage enables adding or removing columns very quickly, even for very large tables. NOTE: New columns are not automatically propagated to associated views, even if a view is created with the wildcard (*). To add new columns to a view, the view must be recreated using the CREATE OR REPLACE VIEW command. Limitations: l Maximum table columns: 1600 columns l You cannot add columns to a temporary table Physical Schema Design - projections Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #63 A projection defines how the records specified by logical tables are actually stored and distributed across the cluster nodes. The following parameters of a physical data representation can be configured using a projection: l l l Columns to be included and column encoding (run-length encoding, delta encoding, etc) Column ordering Segmentation: The rows to keep on the same node and the projections to be replicated instead of split NOTE: Having multiple projections for the same table impedes data updates. You should retain only the necessary projections in your production design. When a new table is created using the CREATE TABLE command, a new superprojection is created automatically. l For more information on the CREATE TABLE extensions that can configure the initial superprojection, see Configuring the Initial Superprojection with CREATE TABLE command. Additional projections can be created using the CREATE PROJECTION command. l l See Creating a New Projection with CREATE PROJECTION command. For more information on replacing existing projections, see Changing Physical Schema. Columns Encoding and Compression Data Warehouse column storage space can be reduced by applying encoding and compression techniques. Available encoding methods include: l run-length encoding (sorted repeating values replaced with the value and a number of occurrences) Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide l dictionary l various delta encodings Page #64 By default, the AUTO encoding is used on column values. This method applies LZO compression to CHAR/VARCHAR, BOOLEAN, BINARY/VARBINARY, and FLOAT columns. l For INTEGER, DATE/TIME/TIMESTAMP, and INTERVAL type columns, Data Warehouse uses a compression scheme based on the delta between consecutive column values. Tip: For sorted, many value columns such as primary keys, the AUTO encoding is usually the best choice. For repeating sorted low cardinality columns, run-length encoding (RLE) may be the right choice. For more detailed information on individual encoding types, see https://my.vertica.com/docs/6.1.x/HTML/index.htm#9273.htm. Columns Sort Order The sort order optimizes for queries based on the query predicate, especially WHERE clauses, GROUP BY or ORDER BY. See also the Choose Projection Sorting Criteria performance tip. Segmentation In a typical Data Warehouse instance, data may be distributed across three or more nodes of a shared or dedicated cluster. By default, Data Warehouse and the underlying Vertica database can manage automatically this distribution. However, in a high-performance database, developers may require better control over how data is distributed. In a Vertica database, segmentation controls how data from a table may be distributed across nodes of a cluster. When a table or projection is created, you can specify segmentation parameters to define how data is distributed. l If segmentation is not specified explicitly, data is segmented by a hash of the projection columns; columns with fewer than 8 bytes are listed first, Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #65 followed by larger columns up to the first 32 columns of the table. NOTE: If segmentation is not configured for your Data Warehouse instance,the default segmentation is likely to utilize broadcast joins, which can impact performance. A custom segmentation can be specified using SEGMENTED BY or UNSEGMENTED clauses of the CREATE PROJECTION or CREATE TABLE commands. The following segmentations options are available: l l l l l l l Hash segmentation Using SEGMENTED BY expression ALL NODES clause after CREATE PROJECTION or CREATE TABLE command The expression is expected to return an integer x for each row in the range: 0 <= x < 263. You should compute this expression using HASH or MODULARHASH function on one or more columns. Replication Using the UNSEGMENTED ALL NODES clause after CREATE PROJECTION or CREATE TABLE command Recommended for small tables with no more than a few million rows that are joined with large ones NOTE: Avoid using range segmentation, which Vertica supports. Range segmentation ties your data to explicitly named nodes on the actual underlying cluster. For more information about tuning the segmentations of your physical design, see the Minimize Network Joins section. Configuring the initial superprojection with CREATE TABLE command Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #66 Each Data Warehouse table must have at least one projection with all columns: a superprojection. Without a superprojection, the database engine does not understand how the data should be stored. Whenever a new table is created using the CREATE TABLE command, a superprojection is also created automatically. The parameters of this initial projection can be configured by the following extensions of the CREATE TABLE command: l l ORDER BY specifies the sort order of the default superprojection SEGMENTED BY expression ALL NODES and UNSEGMENTED ALL NODES configure the segmentation of the default superprojection Example: CREATE TABLE customer ( id INTEGER PRIMARY KEY, name_first VARCHAR(255), name_last VARCHAR(255) ) ORDER BY id SEGMENTED BY HASH(id) ALL NODES NOTE: Unlike the CREATE PROJECTION command, the KSAFE 1 parameter is not required when defining the initial projection. Creating a New Projection with CREATE PROJECTION command A new projection can be created using the CREATE PROJECTION command: CREATE PROJECTION projection-name ( columns-and-encodings ) AS SELECT columns FROM tables [ WHERE join-predicates ] [ ORDER BY columns ] [ hash-segmentation-clause Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #67 | range-segmentation-clause | UNSEGMENTED ALL NODES ] [ KSAFE [ k-num ] ] In this command, you may define the list of columns included in the projection, optionally with encoding information. The sort criteria can be specified as a SELECT query in the ORDER BY clause. The SELECT query may include a join of multiple tables, which creates a prejoined projection. NOTE: A physical design with a pre-join projection requires a strict referential integrity between the involved tables, which can make your loading process more fragile. Unlike a materialized view, a projection is intended to hold the raw table data. For this reason, the SELECT queries in projection definitions cannot include complex transformations, aggregations, or analytic functions. NOTE: The k-num parameter must be always set to 1 when creating an Data Warehouse projection using the CREATE PROJECTION command. NODE: For every projection created using the CREATE PROJECTION command, one of the following must be true: l The projection is replicated (by specifying UNSEGMENTED ALL NODES) l The projection is segmented and created with KSAFE 1. Example: CREATE PROJECTION customer_p AS SELECT id, name_first, name_last FROM customer ORDER BY id SEGMENTED BY HASH(id) ALL NODES KSAFE 1 Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #68 NOTE: After a new projection is created, the data should be refreshed using the START_REFRESH function. For additional details, see Changing Physical Schema. Changing Physical Schema In addition to your initial superprojections, new projections can be created using the CREATE PROJECTION command. A single table can have multiple projections if necessary. NOTE: Having multiple projections for the same table impedes data updates. You should retain only the necessary projections in your production design. NOTE: if you want to replace a superprojection, a new superprojection must be created before the old one is removed. Steps: To change the physical model, please complete the following steps. 1. Review the existing projections in your Data Warehouse instance: SELECT * FROM projections p WHERE p.projection_schema = '[DW_ID]' 2. Run the CREATE PROJECTION commands to create new projections 3. Run the following command to start an asynchronous process of populating the new projections with data: SELECT START_REFRESH(); Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #69 4. Check the status of the refresh process until the process finishes: SELECT * FROM projection_refreshes; 5. Drop projections that are no longer necessary using the DROP PROJECTION command. NOTE: If you are replacing only a superprojection, you must wait until the previously executed projection refresh completes. You cannot drop a projection if it’s the only refreshed superprojection. Troubleshooting: If a projection refresh fails, the projection_refreshes table reports the following error: failed: projection is unsafe Make your projection safe by specifying KSAFE 1 in the CREATE PROJECTION command. You will need the drop your projection and re-create it with the KSAFE parameter. Occasionally, the following error may occur when dropping a projection: ROLLBACK: Projection cannot be dropped because history after AHM would be lost Please try again later. If the problem persists, please contact GoodData Customer Support. Loading Data into Data Warehouse Data is loaded into Data Warehouse using the COPY LOCAL command. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide NOTE: You must use the LOCAL keyword with the COPY commmand for Data Warehouse. See Use COPY FROM LOCAL to Load Data. NOTE: Although INSERT commands are available, it is strongly recommended that you use the COPY command for batch uploads over row-by-row inserts for an optimal load performance. The COPY command supports the following options: COPY table [ column_list ] FROM LOCAL file_list [ BZIP | GZIP ] [WITH PARSER GdcCsvParser] [ DELIMITER STRING_LIT ] [ ESCAPE BY STRING_LIT ] [ ENCLOSED BY STRING_LIT ] [ SKIP NUMBER_LIT ] [ REJECTMAX NUMBER_LIT ] [ EXCEPTIONS exceptions_file ] [ REJECTED DATA rejected_data_file ] [ ABORT ON ERROR ] [ AUTO | DIRECT | TRICKLE ] NOTE:Some common parameters of the COPYcommand are not supported in Data Warehouse. See Limited Parameters of the COPY Command. NOTE: To load uncompressed data, do not include the BZIP or GZIP keywords, and reference an uncompressed source file. The UNCOMPRESSED keyword is not supported. NOTE: Unlike most databases, Data Warehouse does not enforce the uniqueness of primary key columns during load; dupe rows are inserted silently. However, duplicate keys may trigger an error at query time in join queries. Do not assume that Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Page #70 Agile Data Warehousing Service User Guide Page #71 duplicate rows will break the load or will be merged in target tables. To avoid inserting unwanted duplicates, use staging tables. See Merge data using staging tables. Loading Compressed Data To minimize network bandwidth and latency issues, you should compress your data prior to upload to Data Warehouse. NOTE: Only BZIP and GZIP formats are supported by Data Warehouse. Example: COPY customers FROM LOCAL 'customers.csv.gz' GZIP NOTE: To load uncompressed data, do not include the BZIP or GZIP keyword in the above command, and reference an uncompressed file. Use RFC 4180 Compliant CSV files for upload By default, the COPY command expects delimited data even if the delimiter character is not present inside individual data fields. In the RFC 4180 document, the CSV format describes an encoding structure with a delimiter, double quotes, or even newline characters within data fields. The following example is a valid CSV file with a header line and a single data record: product_id,product_name,product_description,product_price 12345,"1"" by 5 Yards Duct Tape","Great choice for your creative projects Super performance strength Available in white, red, green and black",9.95 Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #72 This CSV file looks like the following in a spreadsheet application: product_ product_name id 12345 1" by 5 Yards Duct Tape product_description Great choice for your creative projects product_ price 9.95 Super performance strength Available in white, red, green and black To load CSV data with all escaping possibilities defined in RFC 4180, you must explicitly specify the CSV parser using WITH PARSER GdcCsvParser, which is a GoodData-specific CSV parser in Data Warehouse. Example: COPY customers FROM LOCAL 'customers.csv.gz' GZIP WITH PARSER GdcCsvParser Managing Escape Characters: To load CSV data with all escaped characters, as specified in RFC 4180, you must explicitly specify the CSV parser using the GdcCsvParser, a GoodDataspecific parser for Data Warehouse, and include the escape character using ESCAPE AS: COPY customers FROM LOCAL 'customers.csv.gz' GZIP WITH PARSER GdcCsvParser ESCAPE AS '"' Error Handling By default, any row with fields that cannot be inserted into target columns is discarded silently. This behavior can be overridden with the following modifiers to the COPY command: Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide l l l l Page #73 REJECTMAX number - A maximum number of permitted rejected records before a load fails EXCEPTIONS ’path’ - Local file containing load exceptions, which includes useful error messages for debugging issues REJECTED DATA ’path’ - Local file where rejected rows are to be stored ABORT ON ERROR - The load is cancelled (i.e. no data are loaded) on the first rejected load Examples: COPY customers FROM LOCAL 'customers.csv' ABORT ON ERROR; COPY customers FROM LOCAL 'customers.csv.gz' GZIP WITH PARSER GdcCsvParser EXCEPTIONS '/tmp/exceptions.txt' REJECTED DATA '/tmp/rejected.csv' REJECTMAX 100 Merging Data Using Staging Tables For the following reasons, you should use staging tables when loading data into Data Warehouse: l l Data Warehouse does not support upsert operations. Data Warehouse does not enforce the uniqueness of primary key during data load. However, duplicate records may trigger an error at query time in join queries. You cannot load your data directly into the target table and expect that any matching records already in the table are automatically overwritten. Tip: To manage adding data for records that may already exist in the target table, you should load your data into an empty staging table first. Use the MERGE command to merge the staged data into the target table. Segmentation in Staging: Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #74 There are performance impacts in shuffling data across cluster nodes. Tip: Where possible, use the same segmentation for the staging area as is used in the target table’s projections. Example: CREATE TEMP TABLE in_customer ( id VARCHAR(32) PRIMARY KEY, name_first VARCHAR(255), name_last VARCHAR(255), created_at DATETIME, is_deleted BOOLEAN, ) ON COMMIT PRESERVE ROWS SEGMENTED BY HASH(id) ALL NODES; -- consistent with the target table COPY in_customer FROM LOCAL '/data/customers.csv' ABORT ON ERROR DIRECT; MERGE /*+direct*/ -- "direct" improves the performance of large batch operations INTO customer tgt USING in_customer src ON src.id = tgt.id WHEN MATCHED THEN UPDATE SET name_first = src.name_first, name_last = src.name_ last, created_at = src.created_at, is_deleted = src.is_ deleted WHEN NOT MATCHED THEN INSERT (id, name_first, name_last, created_at, is_deleted) VALUES (src.id, src.name_first, src.name_last, src.created_at, src.is_deleted); Statistics Collection The query optimizer uses statistics about data in your projections to build the optimal query plan. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide l l l Page #75 Keep the statistics up to-date by running the SELECT ANALYZE_ STATISTICS SQL command. The ANALYZE_STATISTICS function returns 0 when it completes successfully. The ANALYZE_STATISTICS command works on a 10% sample of the specified disk data. The sample size can be overridden by using the ANALYZE_HISTOGRAM function instead. Both ANALYZE_STATISTICS and ANALYZE_HISTOGRAM functions autocommit the current transaction. Examples: -- collect statistics for a single table SELECT ANALYZE_STATISTICS('table'); -- collect statistics for a specific column SELECT ANALYZE_STATISTICS('table.column'); -- collect table statistics based on a 0.5% sample SELECT ANALYZE_HISTOGRAM('table', 0.5); -- collect ble statistics based on all data SELECT ANALYZE_HISTOGRAM('table', 100); NOTE: Collecting statistics is a CPU- and memory-intensive operation. You should run ANALYZE_STATISTICS only after the data in your projections changes significantly. Significant changes include the following: l First data load into a table l A data introduces a significant deviation in the data distribution. l A new projection is created and refreshed l l The number of rows or minimum/maximum values in table’s columns change by 50% New primary key values are added to tables with referential integrity constraints (In this case, both parent and child tables should be reanalyzed.) Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide l Page #76 The relative table size, compared to tables to which it is being joined, changes materially. For example, if a table becomes only five times larger than the other, when it was previously 50 times larger, statistics should be analyzed. Querying Data Warehouse Data Warehouse is built on HP Vertica, a leading-edge columnar database, and supports the SQL:99 standard with Vertica specific extensions. l For Vertica version information, see Data Warehouse and Vertica. Vertica supports SQL standards for creating and querying for data. For more information on query capabilities, please use the following Vertica references: l l General querying for data: See Documentation of the SELECT SQL Command. SQL Functions: l Aggregate Functions l Analytic Functions l Date/Time Functions l Formatting Functions l Geospatial Package SQL Functions l IP Conversion Functions l Mathematical Functions l NULL-handling Functions l Pattern Matching Functions l Regular Expression Functions l Sequence Functions l String Functions Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide l Timeseries Functions l URI Encode/Decode Functions l HP Vertica Meta-functions Page #77 NOTE: Vertica functions that require a superuser permissions and most System Information Functions are not supported by Data Warehouse. l l l Analytic functions:Analytic functions return aggregated results. However, the result set is not grouped. Group values are returned with each record. See Using SQL Analytics. Time Series analytics:These analytic functions evaluate the values of a given set of variables over time. Those values are then grouped into buckets, based on a defined time interval, for analysis and aggregation. See Using Time Series Analytics. Event Series joins: This HP Vertica SQL extension enables analysis of two series when their measurement intervals don’t align precisely. For example, mismatched timestamps can be compared. You can compare values from the two series directly, rather than normalizing the two series to the same interval before comparison. See Event Series Joins. Performance Tips In high-volume environments, small changes to the database schema or methods for using the database can have significant impacts on overall performance. Use the tips in this section to improve performance in your Agile Data Warehousing Service solution. Do Not Overnormalize Your Schema For a columnar database engine, denormalization is cheap from a storage point of view, while table joins are expensive. Example: Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #78 When storing the history of changes, you should store all columns of record versions in the same table as the source data, instead of retaining the history of each column in an extra table, to avoid table joins. Use Run Length Encoding (RLE) For sorted columns with many repeating values, you should explicitly use runlength encoding (RLE) in your projections. The default (AUTO) encoding may save some space, but it's slower. However, RLE is not suitable for big high cardinal columns, such as primary keys. These should use the default encoding. Use the EXPLAIN Keyword If your query is running slow, the EXPLAINcommand provides a quick overview of the query plan. Examining the query plan may help to identify possible sources of the inefficiency and can be used to derive possible improvements to the physical database design. The query plan can be retrieved by running the EXPLAIN command followed by the actual SQL query. For more information about analyzing the query plans with the EXPLAIN keyword please use the following Vertica references: l EXPLAIN SQL Command Documentation l Understanding Query Plans Use Monitoring Tables QUERY_EVENTS system table The QUERY_EVENTS system table provides useful information about queries that have been recently executed in your Data Warehouse instance. l See https://my.vertica.com/docs/6.1.x/HTML/index.htm#17580.htm. EVENT_TIMESTAMP column: Timestamp that is recorded when the event occurs, which may assist in identifying the code that was being executed at the time of the event. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #79 EVENT_TYPE column: The following values in the EVENT_TYPE column may indicate a problem that requires attention: PREDICATE OUTSIDE HISTOGRAM The query optimizer encountered a predicate that was false for the entire histogram created by ANALYZE_STATISTICS or ANALYZE HISTOGRAM. NO HISTOGRAM The query optimizer encountered a predicate on a column lacking a histogram. MEMORY LIMIT HIT The optimizer used all allocated memory when creating the query plan. You should simplify your query instead of increasing the memory allocation. EVENT_DESCRIPTION column: The EVENT_DESCRIPTION column provides clear information about the captured events. Below are example messages: GROUP BY key set did not fit in memory, using external sort grouping To fix, you should consider a projection sorted by the GROUP BY key to enable pipelined GROUP BY sorting, which forces only the group that is currently being processed to be retained in memory. l See https://my.vertica.com/docs/6.1.x/HTML/index.htm#16340.htm. Many rows were resegmented during plan execution To fix, you should consider using identically segmented projections. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide l Page #80 For more information, see Minimize Network Joins. The optimized encountered a predicate on a column for which it does not have a histogram The database needs to have statistics updated. For more information, see Statistics Collection. Statement identifiers: In the QUERY_EVENTS table, the combination of TRANSACTION_ID, REQUEST_ ID, and STATEMENT_ID fields uniquely identify the SQL statement, which is located in the QUERY_REQUESTS table (see below). QUERY_REQUESTS table This table retains information about query plans, optimization, and execution events. For any unique combination of TRANSACTION_ID and STATEMENT_ID, the value of the REQUEST field contains the SQL request. REQUEST_TYPE column: The type of the statement (QUERY, DDL, or other) REQUEST column: The text of the SQL statement. SUCCESS column: Boolean value indicates whether the query executed properly. l Errors are logged in the ERROR_MESSAGES system table. START_TIMESTAMP column: Beginning timestamp for the logged event. END_TIMESTAMP column: Ending timestamp for the logged event. Write Large Data Updates Directly to Disk Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #81 By default, all data updates are passed through an in-memory store first. However, the capacity of this memory store is limited, which is why it is more efficient to direct large bulk data uploads or modifications directly into disk. This can be achieved by the DIRECTkeyword in the COPYcommand and the /*+direct*/ hint in INSERT, DELETE and MERGE commands. Examples: COPY table FROM LOCAL 'file.csv' WITH PARSER GdcCsvParser() ABORT ON ERROR DIRECT; MERGE /*+direct*/ INTO opportunities t USING in_opportunities s ON s.id = t.id WHEN MATCHED THEN UPDATE SET name = s.name, created = s.created, closed = s.closed, stage = s.stage, is_closed = s.is_closed, is_won = s.is_won, amount = s.amount WHEN NOT MATCHED THEN INSERT (id, name, created, closed, stage, is_closed, is_won, amount) VALUES (s.id, s.name, s.created, s.closed, s.stage, s.is_ closed, s.is_won, s.amount); Avoid Unnecessary UPDATEs An UPDATEis implemented as a combination of INSERT and UPDATE. Try to design your model and loading routines to avoid UPDATEs of large tables. Example 1: When storing full history of data, do not update old records with an end-of-validity timestamp. Instead, insert new versions only and retrieve end-ofvalidity timestamp at query time when necessary. Example 2: When computing derived columns for existing records, consider inserting them into a separate table, rather than updating existing records. General Projection Design Tips Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #82 When designing projections for your Data Warehouse instance, please observe the following recommendations. Minimize Network Joins Your Data Warehouse instance is typically created within a shared or dedicated cluster of 3+ nodes running HP Vertica, and the data in your tables may be spread across the cluster nodes. Data Warehouse provides options for controlling how your data is distributed. If you retain the system defaults, it is very likely that your table joins will join records sitting on different parts of the clusters, which affect performance. This section some insight into how to minimize network joins. Basic Problem: The following picture includes two randomly segmented projections. To join the tables using these projections by cust_id, you must combine records from different nodes. For example, orders associated with customer #2 are split across all three nodes: Figure: Randomly segmented projections Solution #1: All joined records on the same node To make the join operation more efficient, the records to be joined should be available on the same node, as in the following: Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #83 Figure: Identically segmented projections NOTE: To force records from multiple tables to be stored on the same node for performance efficiency, all tables should contain identically segmented projections. Segmentation can be defined in CREATE TABLE statements, like the following: CREATE TABLE customers ( cust_id INTEGER, name VARCHAR(255) ) SEGMENTED BY HASH(cust_id) ALL NODES; CREATE TABLE orders ( order_id INTEGER, cust_id, INTEGER, order_dt DATE, total DECIMAL(12,2) ) SEGMENTED BY HASH(cust_id) ALL NODES; Solution #2: Replicate data across all nodes. For smaller tables (up to a few hundred thousand records), network joins can be avoided by replicating all customer data across all nodes: Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #84 Figure: Replicated projection of the customers table The corresponding SQL is the following: CREATE TABLE customers ( cust_id INTEGER, name VARCHAR(255) ) UNSEGMENTED ALL NODES; CREATE TABLE orders ( order_id INTEGER, cust_id, INTEGER, order_dt DATE, total DECIMAL(12,2) ); Solution #3: Constrain data to a single node. If all tables are small (up to a few million records), you should consider retaining all data on a single node only: Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #85 Figure: Both projections on the same single node only You can force this constraint by segmenting your projections by a constant that is unique to your implementation such as the Data Warehouse identifier identifier (the HQrKTXGedJ6OngbUJ4QAHrb0pEw5oEif string in the example below). CREATE TABLE customers ( cust_id INTEGER, name VARCHAR(255) ) SEGMENTED BY HASH('HQrKTXGedJ6OngbUJ4QAHrb0pEw5oEif') ALL NODES; CREATE TABLE orders ( order_id INTEGER, cust_id, INTEGER, order_dt DATE, total DECIMAL(12,2) ) SEGMENTED BY HASH('HQrKTXGedJ6OngbUJ4QAHrb0pEw5oEif') ALL NODES; Choose Projection Sorting Criteria When developing your database projections, you should start with the default projection, which is a superprojection containing all fields in the table. Soon, however, you may discover that you need to optimize projections for performance or to create custom projections to address specific query use cases. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #86 Tip: In a production implementation, it is not necessary to optimize your physical model for each query that you intend to run. Instead, you should start slowly and add or modify projections to address specific performance issues or requirements of your database. The sorting criteria that you use in your projections depend on the uses for those projections. Sort criteria should be specified based on requirements for speedy retrieval, memory footprint, and join use cases for the projection. These use cases are best demonstrated by example. The example below is provided for illustrative purposes only. Suppose you have the following three queries on two tables (table and table2): SELECT a, b, c FROM table WHERE c = 'xxxx' ORDER BY b SELECT b, c, SUM(a) FROM table GROUP BY b, c SELECT t.a, t.b, t2.x FROM table t JOIN table2 t2 ON t.a = t2.y To build a physical model that is fully optimized for these three queries, you must create the projections as outlined in the picture below: Figure: Example projections Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide l l l Page #87 projection1 is sorted by c and then by b. This sorting enables quick location of the filtered value for c and returns the result sorted by b. projection2 is sorted by columns used in the GROUP BY clause. This sorting helps to minimize the memory footprint of the GROUP BY query, as the database can retain only group-specific data in memory, instead of maintaining a hash table containing all groups. If table and table2 are large, projection3 and projection4 enable a merge join of pre-sorted columns, instead of loading the smaller table into memory and performing a hash join. Note that the columns C and Z are not present in the projections, as they are not used by the query. NOTE: When building your Data Warehouse database, you are not required to create optimized query-specific projections from scratch. You should start with one superprojection for each table and consider adding additional projections from HP Vertica to improve performance of slow queries. Limitations and Differences in Data Warehouse from Other RDBMS Data Warehouse provides access to most features of HP Vertica with a few exceptions listed in this section. Single Schema per Data Warehouse Instance The current version of Data Warehouse does not permit creation of your own schemata. When you provision an Data Warehouse instance, a default schema with the same name as the DW_ID is created and automatically added into your search path. As a result, you are not required to qualify your tables and views with the schema name. Tip: To separate a logical group of entities, you should establish a naming convention (e.g. “in_” prefix for input stage tables.). No Vertica Admin Access The admin-only features of Vertica are not accessible through Data Warehouse. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #88 Use COPY FROM LOCAL to Load Data The LOCAL keyword in the COPY command tells Vertica that data is being loaded from the client, instead of from a file already located on the nodes of the Vertica cluster. NOTE: The COPY command without the LOCAL keyword does not work in Data Warehouse. Limited Parameters of the COPY Command The following parameters are currently supported by the COPY command. All other parameters are not supported. l LOCAL l WITH PARSER GdcCsvParser l DELIMITER l ESCAPE AS l ENCLOSED BY l SKIP l REJECTMAX l EXCEPTIONS l REJECTED DATA l ABORT ON ERROR l AUTO, DIRECT, or TRICKLE Only a plain list of columns is expected (optionally) after the table name. NOTE: The parameters of the COPY command must be specified in the same order as in the above list. For example, ESCAPE AS must always precede any reference to ENCLOSED BY. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide Page #89 Limited Access to System Tables The majority of Vertica’s system tables from V_MONITORING and V_CATALOG schemata for introspecting your logical (tables) and physical (projections) data model in Data Warehouse are accessible. The available system tables can be accessed only without the schema quantifier: SELECT * FROM tables will work but SELECT * FROM v_catalog.tables will not. The following tables are not available: l ALL_TABLES l DATABASES l ELASTIC_CLUSTER l EPOCHS l FAULT_GROUPS l GRANTS l LICENSE_AUDITS l NODES l ODBC_COLUMNS l PASSWORDS l PROFILE_PARAMETERS l PROFILES l RESOURCE_POOL_DEFAULTS l RESOURCE_POOLS l ROLES l STORAGE_LOCATIONS l SYSTEM_COLUMNS Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide l SYSTEM_TABLES l USER_AUDITS l USERS l ACTIVE_EVENTS l COLUMN_STORAGE l CONFIGURATION_CHANGES l CONFIGURATION_PARAMETERS l CPU_USAGE l CRITICAL_HOSTS l CRITICAL_NODES l CURRENT_SESSION l DATA_COLLECTOR l DATABASE_BACKUPS l DATABASE_CONNECTIONS l DATABASE_SNAPSHOTS l DEPLOY_STATUS l DESIGN_STATUS l DISK_RESOURCE_REJECTIONS l DISK_STORAGE l ERROR_MESSAGES l EVENT_CONFIGURATIONS l HOST_RESOURCES l IO_USAGE Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Page #90 Agile Data Warehousing Service User Guide l LOAD_STREAMS l LOCK_USAGE l LOCKS l LOGIN_FAILURES l MEMORY_USAGE l MONITORING_EVENTS l NETWORK_INTERFACES l NETWORK_USAGE l NODE_RESOURCES l NODE_STATES l PARTITION_REORGANIZE_ERRORS l PARTITION_STATUS l PROCESS_SIGNALS l PROJECTION_RECOVERIES l PROJECTION_REFRESHES l QUERY_METRICS l REBALANCE_PROJECTION_STATUS l REBALANCE_TABLE_STATUS l RECOVERY_STATUS l RESOURCE_POOL_STATUS l RESOURCE_QUEUES l RESOURCE_REJECTIONS l RESOURCE_USAGE Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Page #91 Agile Data Warehousing Service User Guide Page #92 l STORAGE_TIERS l STORAGE_USAGE l SYSTEM l SYSTEM_RESOURCE_USAGE l SYSTEM_SERVICES l SYSTEM_SESSIONS l TUNING_RECOMMENDATIONS l UDX_FENCED_PROCESSES l USER_LIBRARIES l USER_LIBRARY_MANIFEST l USER_SESSIONS l WOS_CONTAINER_STORAGE l For the full list and the documentation of individual system tables, see https://my.vertica.com/docs/6.1.x/HTML/index.htm#9338 .htm. Limited Access to System Functions The following System Information Functions are not supported by Data Warehouse: l CURRENT_DATABASE l CURRENT_SCHEMA l CURRENT_USER l HAS_TABLE_PRIVILEGE l SESSION_USER Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide l USER l USERNAME Page #93 https://my.vertica.com/docs/6.1.x/HTML/index.htm - 16772.htm Moreover, the HP Vertica Meta-functions that require superuser permissions are not supported neither. Reserved Entity Names Your table or view names may not collide with an existing Vertica system table. l For the full list of system tables, see https://my.vertica.com/docs/6.1.x/HTML/index.htm#9338.htm. For example, the following command fails: CREATE TABLE users ( id INTEGER PRIMARY KEY, login VARCHAR (32)) The error message is the following: Referencing object "users" is not allowed Database Designer Tool not available Vertica includes the Database Designer tool to provide hints for designing the physical model (projections). This tool is not available to Data Warehouse users. JDBC Driver Limitations The following methods of the JDBC interface are not implemented: java.sql.Driver l getParentLogger java.sql.Connection Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide l abort l createArrayOf l createBlob l createClob l createNClob l createSQLXML l createStruct l getClientInfo() l getClientInfo(java.lang.String) l getNetworkTimeout l getTypeMap l isWrapperFor l nativeSQL l prepareCall(java.lang.String) l prepareCall(java.lang.String, int, int) l prepareCall(java.lang.String, int, int, int) l prepareStatement(java.lang.String) l prepareStatement(java.lang.String, int) l prepareStatement(java.lang.String, int, int) l prepareStatement(java.lang.String, int, int, int) l prepareStatement(java.lang.String, int[]) l prepareStatement(java.lang.String, java.lang.String[]) l releaseSavepoint Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Page #94 Agile Data Warehousing Service User Guide l rollback(java.sql.Savepoint) l setClientInfo(java.util.Properties) l setClientInfo(java.lang.String, java.lang.String) l setNetworkTimeout l setSavepoint() l setSavepoint(java.lang.String) l setTypeMap l unwrap java.sql.DatabaseMetaData l getRowIdLifetime() l supportsStoredFunctionsUsingCallSyntax() l autoCommitFailureClosesAllResultSets() l getClientInfoProperties() l getFunctions(java.lang.String,java.lang.String,java.lang.String) l l getFunctionColumns (java.lang.String,java.lang.String,java.lang.String,java.lang.String) getPseudoColumns (java.lang.String,java.lang.String,java.lang.String,java.lang.String) l generatedKeyAlwaysReturned() l unwrap(java.lang.Class) l isWrapperFor(java.lang.Class) java.sql.Statement l addBatch l cancel Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Page #95 Agile Data Warehousing Service User Guide l clearBatch l closeOnCompletion l execute(java.lang.String, int[]) l execute(java.lang.String, java.lang.String[]) l executeBatch l executeUpdate(java.lang.String, int[]) l executeUpdate(java.lang.String, java.lang.String[]) l getMaxFieldSize l getQueryTimeout l getResultSetHoldability l isClosed l isCloseOnCompletion l isPoolable l isWrapperFor l setCursorName l setEscapeProcessing l setMaxFieldSize l setPoolable l setQueryTimeout l unwrap java.sql.ResultSet l getTime(java.lang.String,java.util.Calendar) l getTime(int,java.util.Calendar) Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Page #96 Agile Data Warehousing Service User Guide l getDate(int,java.util.Calendar) l getDate(java.lang.String,java.util.Calendar) l getTimestamp(int,java.util.Calendar) l getTimestamp(java.lang.String,java.util.Calendar) l isClosed() l getObject(int,java.lang.Class) l getObject(int,java.util.Map) l getObject(java.lang.String,java.util.Map) l getObject(java.lang.String,java.lang.Class) l getBytes(int) l getBytes(java.lang.String) l getArray(int) l getArray(java.lang.String) l getURL(java.lang.String) l getURL(int) l unwrap(java.lang.Class) l getRef(java.lang.String) l getRef(int) l isWrapperFor(java.lang.Class) l getCursorName() l getHoldability() l getNCharacterStream(int) l getNCharacterStream(java.lang.String) Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Page #97 Agile Data Warehousing Service User Guide l getSQLXML(java.lang.String) l getSQLXML(int) l getNClob(int) l getNClob(java.lang.String) l getClob(java.lang.String) l getClob(int) l getBlob(java.lang.String) l getBlob(int) l getCharacterStream(java.lang.String) l getCharacterStream(int) l getBinaryStream(int) l getBinaryStream(java.lang.String) l getUnicodeStream(java.lang.String) l getUnicodeStream(int) l getAsciiStream(int) l getAsciiStream(java.lang.String) l getRowId(int) l getRowId(java.lang.String) Page #98 java.sql.ResultSet (special cases) In addition to the above, java.sql.ResultSet instances returned by DataBaseMetaData methods or by the Statement#getGeneratedKeys method do not implement the following methods: l clearWarnings l getFetchSize Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Agile Data Warehousing Service User Guide l getWarnings l setFetchSize Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Page #99 Agile Data Warehousing Service User Guide Data Warehouse API Reference For more information on the Data Warehouse APIs, see http://developer.gooddata.com/api#datawarehouse. Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved. Page #100 Copyright © GoodData Corporation 2007 - 2015 All Rights Reserved.
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