Connecting to a SQL Server Data Warehouse with the AWS Schema Conversion Tool - AWS Schema Conversion Tool
Privileges for SQL Server Data WarehouseLimitations for SQL Server Data Warehouse as a source Connecting to SQL Server Data Warehouse as a sourceSQL Server Data Warehouse to Amazon Redshift conversion settingsSQL Server Data Warehouse to Amazon Redshift conversion optimization settings

Connecting to a SQL Server Data Warehouse with the AWS Schema Conversion Tool

You can use AWS SCT to convert schemas, code objects, and application code from Microsoft SQL Server DW to Amazon Redshift or Amazon Redshift and AWS Glue used in combination.

Privileges for Microsoft SQL Server Data Warehouse as a source

The following privileges are required for using Microsoft SQL Server data warehouse as a source:

  • VIEW DEFINITION

  • VIEW DATABASE STATE

  • SELECT ON SCHEMA :: <schema_name>

In the preceding example, replace the <source_schema> placeholder with the name of the source source_schema.

Repeat the grant for each database whose schema you are converting.

In addition, grant the following, and run the grant on the master database:

  • VIEW SERVER STATE

Limitations for SQL Server Data Warehouse as a source

Using Microsoft SQL Server Parallel Data Warehouse (PDW) as a source isn't currently supported.

Connecting to SQL Server Data Warehouse as a source

Use the following procedure to connect to your SQL Server Data Warehouse source database with the AWS Schema Conversion Tool.

To connect to a SQL Server Data Warehouse source database

  1. In the AWS Schema Conversion Tool, choose Add source.

  2. Choose Microsoft SQL Server, then choose Next.

    The Add source dialog box appears.

  3. For Connection name, enter a name for your database. AWS SCT displays this name in the tree in the left panel.

  4. Use database credentials from AWS Secrets Manager or enter them manually:

    • To use database credentials from Secrets Manager, use the following instructions:

      1. For AWS Secret, choose the name of the secret.

      2. Choose Populate to automatically fill in all values in the database connection dialog box from Secrets Manager.

      For information about using database credentials from Secrets Manager, see Configuring AWS Secrets Manager in the AWS Schema Conversion Tool.

    • To enter the Microsoft SQL Server source data warehouse connection information manually, use the following instructions:

      Parameter Action
      Server name

      Enter the Domain Name Service (DNS) name or IP address of your source database server.
      Server port

      Enter the port used to connect to your source database server.

      Instance name

      Enter the instance name for the SQL Server data warehouse.

      User name and Password

      Enter the database credentials to connect to your source database server.

      AWS SCT uses the password to connect to your source database only when you choose to connect to your database in a project. To guard against exposing the password for your source database, AWS SCT doesn't store the password by default. If you close your AWS SCT project and reopen it, you are prompted for the password to connect to your source database as needed.
      Use SSL

      Choose this option to use Secure Sockets Layer (SSL) to connect to your database. Provide the following additional information, as applicable, on the SSL tab:

      • Trust server certificate: Select this option to trust the server certificate.

      • Trust store: A trust store that you set up in the Global settings.
      Store password

      AWS SCT creates a secure vault to store SSL certificates and database passwords. By turning this option on, you can store the database password and connect quickly to the database without having to enter the password.

      SQL Server driver path

      Enter the path to the driver to use to connect to the source database. For more information, see Installing JDBC drivers for AWS Schema Conversion Tool.

      If you store the driver path in the global project settings, the driver path doesn't appear on the connection dialog box. For more information, see Storing driver paths in the global settings.

  5. Choose Test Connection to verify that AWS SCT can connect to your source database.

  6. Choose Connect to connect to your source database.

SQL Server Data Warehouse to Amazon Redshift conversion settings

To edit SQL Server Data Warehouse to Amazon Redshift conversion settings, choose Settings in AWS SCT, and then choose Conversion settings. From the upper list, choose Microsoft SQL Server, and then choose Microsoft SQL Server – Amazon Redshift. AWS SCT displays all available settings for SQL Server Data Warehouse to Amazon Redshift conversion.

SQL Server Data Warehouse to Amazon Redshift conversion settings in AWS SCT include options for the following:

  • To limit the number of comments with action items in the converted code.

    For Add comments in the converted code for the action items of selected severity and higher, choose the severity of action items. AWS SCT adds comments in the converted code for action items of the selected severity and higher.

    For example, to minimize the number of comments in your converted code, choose Errors only. To include comments for all action items in your converted code, choose All messages.

  • To set the maximum number of tables that AWS SCT can apply to your target Amazon Redshift cluster.

    For The maximum number of tables for the target Amazon Redshift cluster, choose the number of tables that AWS SCT can apply to your Amazon Redshift cluster.

    Amazon Redshift has quotas that limit the use tables for different cluster node types. If you choose Auto, AWS SCT determines the number of tables to apply to your target Amazon Redshift cluster depending on the node type. Optionally, choose the value manually. For more information, see Quotas and limits in Amazon Redshift in the Amazon Redshift Management Guide.

    AWS SCT converts all your source tables, even if this is more than your Amazon Redshift cluster can store. AWS SCT stores the converted code in your project and doesn't apply it to the target database. If you reach the Amazon Redshift cluster quota for the tables when you apply the converted code, then AWS SCT displays a warning message. Also, AWS SCT applies tables to your target Amazon Redshift cluster until the number of tables reaches the limit.

  • To migrate partitions of the source table to separate tables in Amazon Redshift. To do so, select Use the UNION ALL view and enter the maximum number of target tables that AWS SCT can create for a single source table.

    Amazon Redshift doesn't support table partitioning. To emulate this behavior and make queries run faster, AWS SCT can migrate each partition of your source table to a separate table in Amazon Redshift. Then, AWS SCT creates a view that includes data from all these tables.

    AWS SCT automatically determines the number of partitions in your source table. Depending on the type of source table partitioning, this number can exceed the quota for the tables that you can apply to your Amazon Redshift cluster. To avoid reaching this quota, enter the maximum number of target tables that AWS SCT can create for partitions of a single source table. The default option is 368 tables, which represents a partition for 366 days of a year and two tables for NO RANGE and UNKNOWN partitions.

  • To apply compression to Amazon Redshift table columns. To do so, select Use compression encoding.

    AWS SCT assigns compression encoding to columns automatically using the default Amazon Redshift algorithm. For more information, see Compression encodings in the Amazon Redshift Database Developer Guide.

    By default, Amazon Redshift doesn't apply compression to columns that are defined as sort and distribution keys. You can change this behavior and apply compression to these columns. To do so, select Use compression encoding for KEY columns. You can select this option only when you select the Use compression encoding option.

SQL Server Data Warehouse to Amazon Redshift conversion optimization settings

To edit SQL Server Data Warehouse to Amazon Redshift conversion optimization settings, choose Settings in AWS SCT, and then choose Conversion settings. From the upper list, choose Microsoft SQL Server, and then choose Microsoft SQL Server – Amazon Redshift. In the left pane, choose Optimization strategies. AWS SCT displays conversion optimization settings for SQL Server Data Warehouse to Amazon Redshift conversion.

SQL Server Data Warehouse to Amazon Redshift conversion optimization settings in AWS SCT include options for the following:

  • To work with automatic table optimization. To do so, select Use Amazon Redshift automatic table tuning.

    Automatic table optimization is a self-tuning process in Amazon Redshift that automatically optimizes the design of tables. For more information, see Working with automatic table optimization in the Amazon Redshift Database Developer Guide.

    To rely only on the automatic table optimization, choose None for Initial key selection strategy.

  • To choose sort and distribution keys using your strategy.

    You can choose sort and distribution keys using Amazon Redshift metadata, statistical information, or both these options. For Initial key selection strategy on the Optimization strategies tab, choose one of the following options:

    • Use metadata, ignore statistical information

    • Ignore metadata, use statistical information

    • Use metadata and statistical information

    Depending on the option that you choose, you can select optimization strategies. Then, for each strategy, enter the value (0–100). These values define the weight of each strategy. Using these weight values, AWS SCT defines how each rule influences on the choice of distribution and sort keys. The default values are based on the AWS migration best practices.

    You can define the size of small tables for the Find small tables strategy. For Min table row count and Max table row count, enter the minimum and maximum number of rows in a table to define it as a small table. AWS SCT applies the ALL distribution style to small tables. In this case, a copy of the entire table is distributed to every node.

  • To configure strategy details.

    In addition to defining the weight for each optimization strategy, you can configure the optimization settings. To do so, choose Conversion optimization.

    • For Sort key columns limit, enter the maximum number of columns in the sort key.

    • For Skewed threshold value, enter the percentage (0–100) of a skewed value for a column. AWS SCT excludes columns with the skew value greater than the threshold from the list of candidates for the distribution key. AWS SCT defines the skewed value for a column as the percentage ratio of the number of occurrences of the most common value to the total number of records.

    • For Top N queries from the query history table, enter the number (1–100) of the most frequently used queries to analyze.

    • For Select statistics user, choose the database user for which you want to analyze the query statistics.

    Also, on the Optimization strategies tab, you can define the size of small tables for the Find small tables strategy. For Min table row count and Max table row count, enter the minimum and maximum number of rows in a table to consider it as a small table. AWS SCT applies the ALL distribution style to small tables. In this case, a copy of the entire table is distributed to every node.