Generate metadata for translation and assessment

This document describes how to create metadata and query log files by using the dwh-migration-dumper command-line extraction tool. The metadata files describe the SQL objects in your source system.

BigQuery Migration Service uses this information to improve the translation of your SQL scripts from your source system dialect to GoogleSQL.

The BigQuery migration assessment uses metadata files and query log files to analyze your existing data warehouse and help assess the effort of moving your data warehouse to BigQuery.

Overview

You can use the dwh-migration-dumper tool to extract metadata information from the database platform that you are migrating to BigQuery. While using the extraction tool isn't required for translation, it is required for BigQuery migration assessment and we strongly recommend using it for all migration tasks.

For more information, see Create metadata files.

You can use the dwh-migration-dumper tool to extract metadata from the following database platforms:

Teradata
Amazon Redshift
Apache Hive
Apache Spark
Azure Synapse
Microsoft SQL Server
IBM Netezza
Oracle
Snowflake
Trino or PrestoSQL
Vertica

For most of these databases you can also extract query logs.

The dwh-migration-dumper tool queries system tables to gather data definition language (DDL) statements related to user and system databases. It does not query the contents of user databases. The tool saves the metadata information from the system tables as CSV files and then zips these files into a single package. You then upload this zip file to Cloud Storage when you upload your source files for translation or assessment.

When using the query logs option, the dwh-migration-dumper tool queries system tables for DDL statements and query logs related to user and system databases. These are saved in CSV or yaml format to a subdirectory, and then packed into a zip package. At no point are the contents of user databases queried themselves. At this point, the BigQuery migration assessment requires individual CSV, YAML and text files for query logs so you should unzip all of these files from query logs zip file and upload them for assessment.

The dwh-migration-dumper tool can run on Windows, macOS, and Linux.

The dwh-migration-dumper tool is available under the Apache 2 license.

If you choose not to use the dwh-migration-dumper tool for translation, you can manually provide metadata files by collecting the data definition language (DDL) statements for the SQL objects in your source system into separate text files.

Providing metadata and query logs extracted with the tool is required for migration assessment using BigQuery migration assessment.

Compliance requirements

We provide the compiled dwh-migration-dumper tool binary for ease of use. If you need to audit the tool to ensure that it meets compliance requirements, you can review the source code from the dwh-migration-dumper tool GitHub repository, and compile your own binary.

Prerequisites

Install Java

The server on which you plan to run dwh-migration-dumper tool must have Java 8 or higher installed. If it doesn't, download Java from the Java downloads page and install it.

Required permissions

The user account that you specify for connecting the dwh-migration-dumper tool to the source system must have permissions to read metadata from that system. Confirm that this account has appropriate role membership to query the metadata resources available for your platform. For example, INFORMATION_SCHEMA is a metadata resource that is common across several platforms.

Install the `dwh-migration-dumper` tool

To install the dwh-migration-dumper tool, follow these steps:

On the machine where you want to run the dwh-migration-dumper tool, download the zip file from the dwh-migration-dumper tool GitHub repository.
Download the SHA256SUMS.txt file and run the following command:
```
sha256sum --check SHA256SUMS.txt
```
If verification fails, see Troubleshooting.
Extract the zip file. The extraction tool binary is in the /bin subdirectory of the folder created by extracting the zip file.
Update the PATH environment variable to include the installation path for the extraction tool.

Run the `dwh-migration-dumper` tool

The dwh-migration-dumper tool uses the following format:

dwh-migration-dumper [FLAGS]

Running the dwh-migration-dumper tool creates an output file named dwh-migration-<source platform>-metadata.zip—for example, dwh-migration-teradata-metadata.zip, in your working directory.

Use the following instructions to learn how to run the dwh-migration-dumper tool for your source platform.

Teradata

To allow the dwh-migration-dumper tool to connect to Teradata, download their JDBC driver from Teradata's download page.

The following table describes the commonly used flags for extracting Teradata metadata and query logs by using the extraction tool. For information about all supported flags, see global flags.

Name	Default value	Description	Required
`--assessment`		Turns on assessment mode when generating database logs or extracting metadata. The `dwh-migration-dumper` tool generates required metadata statistics for BigQuery migration assessment when used for metadata extraction. When used for query logs it extracts additional columns for BigQuery migration assessment.	Required when using for running assessment, not required for translation.
`--connector`		The name of the connector to use, in this case teradata for metadata or teradata-logs for query logs.	Yes
`--database`		A list of the databases to extract, separated by commas. The database names might be case-sensitive, depending on the Teradata server configuration. If this flag is used in combination with the `teradata` connector, then the `dwh-migration-dumper` tool filters the metadata tables and views by the provided list of databases. The exceptions are the `DatabasesV` and `RoleMembersV` views - the `dwh-migration-dumper` tool extracts the databases and users from these views without filtering by the database name. This flag cannot be used in combination with the `teradata-logs` connector. Query logs are always extracted for all the databases.	No
`--driver`		The absolute or relative path to the driver JAR file to use for this connection. You can specify multiple driver JAR files, separating them by commas.	Yes
`--host`	localhost	The hostname or IP address of the database server.	No
`--password`		The password to use for the database connection.	If not specified, the extraction tool uses a secure prompt to request it.
`--port`	1025	The port of the database server.	No
`--user`		The username to use for the database connection.	Yes
`--query-log-alternates`		For the `teradata-logs` connector only. To extract the query logs from an alternative location, we recommend that you use the `-Dteradata-logs.query-logs-table` and `-Dteradata-logs.sql-logs-table` flags instead. By default, the query logs are extracted from the tables `dbc.DBQLogTbl` and `dbc.DBQLSQLTbl`. If you use the `--assessment` flag, then the query logs are extracted from the view `dbc.QryLogV` and from the table `dbc.DBQLSQLTbl`. If you need to extract the query logs from an alternative location, you can specify the fully-qualified names of the tables or views by using the `--query-log-alternates` flag. The first parameter references the alternative to the `dbc.DBQLogTbl` table, and the second parameter references the alternative to the `dbc.DBQLSQLTbl` table. Both parameters are required. The `-Dteradata-logs.log-date-column` flag can be used to improve extraction performance when both tables have an indexed column of type `DATE`. Example: `--query-log-alternates historicdb.ArchivedQryLogV,historicdb.ArchivedDBQLSqlTbl`	No
`-Dteradata.tmode`		The transaction mode for the connection. The following values are supported: `ANSI`: ANSI mode. This is the default mode (if the flag is not specified) `TERA`: Teradata transaction mode (BTET) `DEFAULT`: use the default transaction mode configured on the database server `NONE`: no mode is set for the connection Example (Bash): `-Dteradata.tmode=TERA` Example (Windows PowerShell): `"-Dteradata.tmode=TERA"`	No
`-Dteradata-logs.log-date-column`		For the `teradata-logs` connector only. To improve performance of joining tables that are specified by the `-Dteradata-logs.query-logs-table` and `-Dteradata-logs.sql-logs-table` flags, you can include an additional column of type `DATE` in the `JOIN` condition. This column must be defined in both tables and it must be part of the Partitioned Primary Index. Example (Bash): `-Dteradata-logs.log-date-column=ArchiveLogDate` Example (Windows PowerShell): `"-Dteradata-logs.log-date-column=ArchiveLogDate"`	No
`-Dteradata-logs.query-logs-table`		For the `teradata-logs` connector only. By default, the query logs are extracted from the `dbc.DBQLogTbl` table. If you use the `--assessment` flag, then the query logs are extracted from the view `dbc.QryLogV`. If you need to extract the query logs from an alternative location, you can specify the fully-qualified name of the table or view by using this flag. See `-Dteradata-logs.log-date-column` flag to improve extraction performance. Example (Bash): `-Dteradata-logs.query-logs-table=historicdb.ArchivedQryLogV` Example (Windows PowerShell): `"-Dteradata-logs.query-logs-table=historicdb.ArchivedQryLogV"`	No
`-Dteradata-logs.sql-logs-table`		For the `teradata-logs` connector only. By default, the query logs containing SQL text are extracted from the `dbc.DBQLSqlTbl` table. If you need to extract them from an alternative location, you can specify the fully-qualified name of the table or view by using this flag. See `-Dteradata-logs.log-date-column` flag to improve extraction performance. Example (Bash): `-Dteradata-logs.sql-logs-table=historicdb.ArchivedDBQLSqlTbl` Example (Windows PowerShell): `"-Dteradata-logs.sql-logs-table=historicdb.ArchivedDBQLSqlTbl"`	No
`-Dteradata-logs.utility-logs-table`		For the `teradata-logs` connector only. By default, the utility logs are extracted from the table `dbc.DBQLUtilityTbl`. If you need to extract the utility logs from an alternative location, you can specify the fully-qualified name of the table by using the `-Dteradata-logs.utility-logs-table` flag. Example (Bash): `-Dteradata-logs.utility-logs-table=historicdb.ArchivedUtilityLogs` Example (Windows PowerShell): `"-Dteradata-logs.utility-logs-table=historicdb.ArchivedUtilityLogs"`	No
`-Dteradata-logs.res-usage-scpu-table`		For the `teradata-logs` connector only. By default, the SCPU resource usage logs are extracted from the table `dbc.ResUsageScpu`. If you need to extract these from an alternative location, you can specify the fully-qualified name of the table by using the `-Dteradata-logs.res-usage-scpu-table` flag. Example (Bash): `-Dteradata-logs.res-usage-scpu-table=historicdb.ArchivedResUsageScpu` Example (Windows PowerShell): `"-Dteradata-logs.res-usage-scpu-table=historicdb.ArchivedResUsageScpu"`	No
`-Dteradata-logs.res-usage-spma-table`		For the `teradata-logs` connector only. By default, the SPMA resource usage logs are extracted from the table `dbc.ResUsageSpma`. If you need to extract these logs from an alternative location, you can specify the fully-qualified name of the table by using the `-Dteradata-logs.res-usage-spma-table` flag. Example (Bash): `-Dteradata-logs.res-usage-spma-table=historicdb.ArchivedResUsageSpma` Example (Windows PowerShell): `"-Dteradata-logs.res-usage-spma-table=historicdb.ArchivedResUsageSpma"`	No
`--query-log-start`		The start time (inclusive) for query logs to extract. The value is truncated to the hour. This flag is only available for the teradata-logs connector. Example: `--query-log-start "2023-01-01 14:00:00"`	No
`--query-log-end`		The end time (exclusive) for query logs to extract. The value is truncated to the hour. This flag is only available for the teradata-logs connector. Example: `--query-log-end "2023-01-15 22:00:00"`	No
`-Dteradata.metadata.tablesizev.max-rows`		For the `teradata` connector only. Limit the number of rows extracted from the view `TableSizeV`. The rows are grouped by the columns `DatabaseName`, `AccountName`, and `TableName`, and then sorted in descending order by the size of the permanent space (the expression `SUM(CurrentPerm)`). Then, the specified number of rows are extracted. Example (Bash): `-Dteradata.metadata.tablesizev.max-rows=100000` Example (Windows PowerShell): `"-Dteradata.metadata.tablesizev.max-rows=100000"`	No
`-Dteradata.metadata.diskspacev.max-rows`		For the `teradata` connector only. Limit the number of rows extracted from the view `DiskSpaceV`. The rows are sorted in descending order by the size of the permanent space (column `CurrentPerm`), and then the specified number of rows are extracted. Example (Bash): `-Dteradata.metadata.diskspacev.max-rows=100000` Example (Windows PowerShell): `"-Dteradata.metadata.diskspacev.max-rows=100000"`	No
`-Dteradata.metadata.databasesv.users.max-rows`		For the `teradata` connector only. Limit the number of rows that represent users (`DBKind='U'`) that are extracted from the view `DatabasesV`. The rows are sorted in descending order by the column `PermSpace`, and then the specified number of rows are extracted. Example (Bash): `-Dteradata.metadata.databasesv.users.max-rows=100000` Example (Windows PowerShell): `"-Dteradata.metadata.databasesv.users.max-rows=100000"`	No
`-Dteradata.metadata.databasesv.dbs.max-rows`		For the `teradata` connector only. Limit the number of rows that represent databases (`DBKind='D'`) that are extracted from the view `DatabasesV`. The rows are sorted in descending order by the column `PermSpace`, and then the specified number of rows are extracted. Example (Bash): `-Dteradata.metadata.databasesv.dbs.max-rows=100000` Example (Windows PowerShell): `"-Dteradata.metadata.databasesv.dbs.max-rows=100000"`	No
`-Dteradata.metadata.max-text-length`		For the `teradata` connector only. Maximum length of the text column when extracting the data from the `TableTextV` view. Text longer than the defined limit will be split into multiple rows. Allowed range: between 5000 and 32000 (inclusive). Example (Bash): `-Dteradata.metadata.max-text-length=10000` Example (Windows PowerShell): `"-Dteradata.metadata.max-text-length=10000"`	No
`-Dteradata-logs.max-sql-length`		For the `teradata-logs` connector only. Maximum length of the `DBQLSqlTbl.SqlTextInfo` column. Query text longer than the defined limit will be split into multiple rows. Allowed range: between 5000 and 31000 (inclusive). Example (Bash): `-Dteradata-logs.max-sql-length=10000` Example (Windows PowerShell): `"-Dteradata-logs.max-sql-length=10000"`	No

Examples

The following example shows how to extract metadata for two Teradata databases on the local host:

dwh-migration-dumper \
  --connector teradata \
  --user user \
  --password password \
  --database database1,database2 \
  --driver path/terajdbc4.jar

The following example shows how to extract query logs for Assessment on the local host for authentication:

dwh-migration-dumper \
  --connector teradata-logs \
  --assessment \
  --user user \
  --password password \
  --driver path/terajdbc4.jar

Tables and views extracted by the `dwh-migration-dumper` tool

The following tables and views are extracted when you use the teradata connector:

DBC.ColumnsV
DBC.DatabasesV
DBC.DBCInfo
DBC.FunctionsV
DBC.IndicesV
DBC.PartitioningConstraintsV
DBC.TablesV
DBC.TableTextV

The following additional tables and views are extracted when you use the teradata connector with --assessment flag:

DBC.All_RI_ChildrenV
DBC.All_RI_ParentsV
DBC.AllTempTablesVX
DBC.DiskSpaceV
DBC.RoleMembersV
DBC.StatsV
DBC.TableSizeV

The following tables and views are extracted when you use the teradata-logs connector:

DBC.DBQLogTbl (changes to DBC.QryLogV if --assessment flag is used)
DBC.DBQLSqlTbl

The following additional tables and views are extracted when you use the teradata-logs connector with --assessment flag:

DBC.DBQLUtilityTbl
DBC.ResUsageScpu
DBC.ResUsageSpma

Redshift

You can use any of the following Amazon Redshift authentication and authorization mechanisms with the extraction tool:

A username and password.
An AWS Identity and Access Management (IAM) access key ID and secret key.
An AWS IAM profile name.

To authenticate with the username and password, use the Amazon Redshift default PostgreSQL JDBC driver. To authenticate with AWS IAM, use the Amazon Redshift JDBC driver, which you can download from their download page.

The following table describes the commonly used flags for extracting Amazon Redshift metadata and query logs by using the dwh-migration-dumper tool. For information about all supported flags, see global flags.

Name	Default value	Description	Required
`--assessment`		Turning on assessment mode when generating database logs or extracting metadata. It generates required metadata statistics for BigQuery migration assessment when used for metadata extraction. When used for query logs extraction it generates query metrics statistics for BigQuery migration assessment.	Required when running in assessment mode, not required for translation.
`--connector`		The name of the connector to use, in this case redshift for metadata or redshift-raw-logs for query logs.	Yes
`--database`	If not specified, Amazon Redshift uses the `--user` value as the default database name.	The name of the database to connect to.	No
`--driver`	If not specified, Amazon Redshift uses the default PostgreSQL JDBC driver.	The absolute or relative path to the driver JAR file to use for this connection. You can specify multiple driver JAR files, separating them by commas.	No
`--host`	localhost	The hostname or IP address of the database server.	No
`--iam-accesskeyid`		The AWS IAM access key ID to use for authentication. The access key is a string of characters, something like `AKIAIOSFODNN7EXAMPLE`. Use in conjunction with the `--iam-secretaccesskey` flag. Do not use this flag when specifying the `--iam-profile` or `--password` flags.	Not explicitly, but you must provide authentication information through one of the following methods: Using this flag in conjunction with the `--iam-secretaccesskey` flag. Using the `--iam-profile` flag. Using the `--password` flag in conjunction with the `--user` flag.
`--iam-profile`		The AWS IAM profile to use for authentication. You can retrieve a profile value to use by examining the `$HOME/.aws/credentials` file or by running `aws configure list-profiles`. Do not use this flag with the `--iam-accesskeyid`, `--iam-secretaccesskey` or `--password` flags.	Not explicitly, but you must provide authentication information through one of the following methods: Using this flag. Using the `--iam-accesskeyid` flag in conjunction with the `--iam-secretaccesskey` flag. Using the `--password` flag in conjunction with the `--user` flag.
`--iam-secretaccesskey`		The AWS IAM secret access key to use for authentication. The secret access key is a string of characters, something like `wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY`. Use in conjunction with the `--iam-accesskeyid` flag. Do not use this flag with the `--iam-profile` or `--password` flags.	Not explicitly, but you must provide authentication information through one of the following methods: Using this flag in conjunction with the `--iam-accesskeyid` flag. Using the `--iam-profile` flag. Using the `--password` flag in conjunction with the `--user` flag.
`--password`		The password to use for the database connection. Do not use this flag with the `--iam-accesskeyid`, `--iam-secretaccesskey` or `--iam-profile` flags.	Not explicitly, but you must provide authentication information through one of the following methods: Using this flag in conjunction with the `--user` flag. Using the `--iam-accesskeyid` flag in conjunction with the `--iam-secretaccesskey` flag. Using the `--password` flag.
`--port`	5439	The port of the database server.	No
`--user`		The username to use for the database connection.	Yes
`--query-log-start`		The start time (inclusive) for query logs to extract. The value is truncated to the hour. This flag is only available for the redshift-raw-logs connector. Example: `--query-log-start "2023-01-01 14:00:00"`	No
`--query-log-end`		The end time (exclusive) for query logs to extract. The value is truncated to the hour. This flag is only available for the redshift-raw-logs connector. Example: `--query-log-end "2023-01-15 22:00:00"`	No

Examples

The following example shows how to extract metadata from an Amazon Redshift database on a specified host, using AWS IAM keys for authentication:

dwh-migration-dumper \
  --connector redshift \
  --database database \
  --driver path/redshift-jdbc42-version.jar \
  --host host.region.redshift.amazonaws.com \
  --iam-accesskeyid access_key_ID \
  --iam-secretaccesskey secret_access-key \
  --user user

The following example shows how to extract metadata from an Amazon Redshift database on the default host, using the username and password for authentication:

dwh-migration-dumper \
  --connector redshift \
  --database database \
  --password password \
  --user user

The following example shows how to extract metadata from an Amazon Redshift database on a specified host, using an AWS IAM profile for authentication:

dwh-migration-dumper \
  --connector redshift \
  --database database \
  --driver path/redshift-jdbc42-version.jar \
  --host host.region.redshift.amazonaws.com \
  --iam-profile profile \
  --user user \
  --assessment

The following example shows how to extract query logs for Assessment from an Amazon Redshift database on a specified host, using an AWS IAM profile for authentication:

dwh-migration-dumper \
  --connector redshift-raw-logs \
  --database database \
  --driver path/redshift-jdbc42-version.jar \
  --host 123.456.789.012 \
  --iam-profile profile \
  --user user \
  --assessment

Tables and views extracted by the `dwh-migration-dumper` tool

The following tables and views are extracted when you use the redshift connector:

SVV_COLUMNS
SVV_EXTERNAL_COLUMNS
SVV_EXTERNAL_DATABASES
SVV_EXTERNAL_PARTITIONS
SVV_EXTERNAL_SCHEMAS
SVV_EXTERNAL_TABLES
SVV_TABLES
SVV_TABLE_INFO
INFORMATION_SCHEMA.COLUMNS
PG_CAST
PG_DATABASE
PG_LANGUAGE
PG_LIBRARY
PG_NAMESPACE
PG_OPERATOR
PG_PROC
PG_TABLE_DEF
PG_TABLES
PG_TYPE
PG_VIEWS

The following additional tables and views are extracted when you use the redshift connector with --assessment flag:

SVV_DISKUSAGE
STV_MV_INFO
STV_WLM_SERVICE_CLASS_CONFIG
STV_WLM_SERVICE_CLASS_STATE

The following tables and views are extracted when you use the redshift-raw-logs connector:

STL_DDLTEXT
STL_QUERY
STL_QUERYTEXT
PG_USER

The following additional tables and views are extracted when you use the redshift-raw-logs connector with --assessment flag:

STL_QUERY_METRICS
SVL_QUERY_QUEUE_INFO
STL_WLM_QUERY

For information about the system views and tables in Redshift, see Redshift system views and Redshift system catalog tables.

Apache Hive/Spark or Trino/PrestoSQL

The dwh-migration-dumper tool only supports authentication to Apache Hive metastore through Kerberos. So the --user and --password flags aren't used, instead use the --hive-kerberos-url flag to supply the Kerberos authentication details.

The following table describes the commonly used flags for extracting Apache Hive, Spark, Presto, or Trino metadata by using the extraction tool. For information about all supported flags, see global flags.

Name	Default value	Description	Required
`--assessment`		Turns on assessment mode when extracting metadata. The `dwh-migration-dumper` tool generates required metadata statistics for BigQuery migration assessment when used for metadata extraction.	Required for assessment. Not required for translation.
`--connector`		The name of the connector to use, in this case hiveql.	Yes
`--hive-metastore-dump-partition-metadata`	true	Causes the `dwh-migration-dumper` tool to extract partition metadata. You might want to set this flag to `false` for production metastore with a significant number of partitions, due to Thrift client performance implications. This improves the extraction tool performance, but causes some loss of partition optimization on the BigQuery side. Don't use this flag with the `--assessment` flag, as it will have no effect.	No
`--hive-metastore-version`	2.3.6	When you run the `dwh-migration-dumper` tool, it selects the appropriate Thrift specification to use for communicating with your Apache Hive server, based on the value of this flag. If the extraction tool doesn't have an appropriate Thrift specification, it uses the 2.3.6 client and emits a warning to `stdout`. If this occurs, please contact Support and provide the Apache Hive version number you requested.	No
`--host`	localhost	The hostname or IP address of the database server.	No
`--port`	9083	The port of the database server.	No
`--hive-kerberos-url`		The Kerberos principal and host to use for authentication.	Required for clusters with enabled Kerberos authentication.
`-Dhiveql.rpc.protection`		The RPC protection configuration level. This determines the Quality of Protection (QOP) of the Simple Authentication and Security Layer (SASL) connection between cluster and the `dwh-migration-dumper` tool. Must be equal to the value of the `hadoop.rpc.protection` parameter inside the `/etc/hadoop/conf/core-site.xml` file on the cluster, with one of the following values: `authentication` `integrity` `privacy` Example (Bash): `-Dhiveql.rpc.protection=privacy` Example (Windows PowerShell): `"-Dhiveql.rpc.protection=privacy"`	Required for clusters with enabled Kerberos authentication.

Examples

The following example shows how to extract metadata for a Hive 2.3.7 database on a specified host, without authentication and using an alternate port for connection:

dwh-migration-dumper \
  --connector hiveql \
  --hive-metastore-version 2.3.7 \
  --host host \
  --port port

To use Kerberos authentication, sign in as a user that has read permissions to the Hive metastore and generate a Kerberos ticket. Then, generate the metadata zip file with the following command:

JAVA_OPTS="-Djavax.security.auth.useSubjectCredsOnly=false" \
  dwh-migration-dumper \
  --connector hiveql \
  --host host \
  --port port \
  --hive-kerberos-url principal/kerberos_host

Azure Synapse or Microsoft SQL Server

To allow the dwh-migration-dumper tool to connect to Azure Synapse or Microsoft SQL Server, download their JDBC driver from Microsoft's download page.

The following table describes the commonly used flags for extracting Azure Synapse or Microsoft SQL Server metadata by using the extraction tool. For information about all supported flags, see global flags.

Name	Default value	Description	Required
`--connector`		The name of the connector to use, in this case sqlserver.	Yes
`--database`		The name of the database to connect to.	Yes
`--driver`		The absolute or relative path to the driver JAR file to use for this connection. You can specify multiple driver JAR files, separating them by commas.	Yes
`--host`	localhost	The hostname or IP address of the database server.	No
`--password`		The password to use for the database connection.	Yes
`--port`	1433	The port of the database server.	No
`--user`		The username to use for the database connection.	Yes

Examples

The following example shows how to extract metadata from an Azure Synapse database on a specified host:

dwh-migration-dumper \
  --connector sqlserver \
  --database database \
  --driver path/mssql-jdbc.jar \
  --host server_name.sql.azuresynapse.net \
  --password password \
  --user user

Netezza

To allow the dwh-migration-dumper tool to connect to IBM Netezza, you must get their JDBC driver. You can usually get the driver from the /nz/kit/sbin directory on your IBM Netezza appliance host. If you can't locate it there, ask your system administrator for help, or read Installing and Configuring JDBC in the IBM Netezza documentation.

The following table describes the commonly used flags for extracting IBM Netezza metadata by using the extraction tool. For information about all supported flags, see global flags.

Name	Default value	Description	Required
`--connector`		The name of the connector to use, in this case netezza.	Yes
`--database`		A list of the databases to extract, separated by commas.	Yes
`--driver`		The absolute or relative path to the driver JAR file to use for this connection. You can specify multiple driver JAR files, separating them by commas.	Yes
`--host`	localhost	The hostname or IP address of the database server.	No
`--password`		The password to use for the database connection.	Yes
`--port`	5480	The port of the database server.	No
`--user`		The username to use for the database connection.	Yes

Examples

The following example shows how to extract metadata for two IBM Netezza databases on a specified host:

dwh-migration-dumper \
  --connector netezza \
  --database database1,database2 \
  --driver path/nzjdbc.jar \
  --host host \
  --password password \
  --user user

Oracle

To allow the dwh-migration-dumper tool to connect to Oracle, download their JDBC driver from Oracle's download page.

The following table describes the commonly used flags for extracting Oracle metadata by using the extraction tool. For information about all supported flags, see global flags.

Name	Default value	Description	Required
`--connector`		The name of the connector to use, in this case oracle.	Yes
`--driver`		The absolute or relative path to the driver JAR file to use for this connection. You can specify multiple driver JAR files, separating them by commas.	Yes
`--host`	localhost	The hostname or IP address of the database server.	No
`--oracle-service`		The Oracle service name to use for the connection.	Not explicitly, but you must specify either this flag or the `--oracle-sid` flag.
`--oracle-sid`		The Oracle system identifier (SID) to use for the connection.	Not explicitly, but you must specify either this flag or the `--oracle-service` flag.
`--password`		The password to use for the database connection.	If not specified, the extraction tool uses a secure prompt to request it.
`--port`	1521	The port of the database server.	No
`--user`		The username to use for the database connection. The user you specify must have the role `SELECT_CATALOG_ROLE` in order to extract metadata. To see whether the user has the required role, run the query `select granted_role from user_role_privs;` against the Oracle database.	Yes

Examples

The following example shows how to extract metadata for an Oracle database on a specified host, using the Oracle service for the connection:

dwh-migration-dumper \
  --connector oracle \
  --driver path/ojdbc8.jar \
  --host host \
  --oracle-service service_name \
  --password password \
  --user user

Snowflake

The following table describes the commonly used flags for extracting Snowflake metadata by using the dwh-migration-dumper tool. For information about all supported flags, see global flags.

Name	Default value	Description	Required
`--connector`		The name of the connector to use, in this case snowflake.	Yes
`--database`		The name of the database to connect to. You can only extract from one database at a time from Snowflake.	Yes
`--host`	localhost	The hostname or IP address of the database server.	No
`--password`		The password to use for the database connection.	If not specified, the extraction tool uses a secure prompt to request it.
`--role`		The Snowflake role to use for authorization. You only need to specify this for large installations where you need to get metadata from the `SNOWFLAKE.ACCOUNT_USAGE` schema instead of `INFORMATION_SCHEMA`. For more information, see Working with large Snowflake instances.	No
`--user`		The username to use for the database connection.	Yes
`--warehouse`		The Snowflake warehouse to use for processing metadata queries.	Yes

Examples

The following example shows how to extract metadata for a typically sized Snowflake database on the local host:

dwh-migration-dumper \
  --connector snowflake \
  --database database \
  --password password \
  --user user \
  --warehouse warehouse

The following example shows how to extract metadata for a large Snowflake database on a specified host:

dwh-migration-dumper \
  --connector snowflake \
  --database database \
  --host "account.snowflakecomputing.com" \
  --password password \
  --role role \
  --user user \
  --warehouse warehouse

Working with large Snowflake instances

The dwh-migration-dumper tool reads metadata from the Snowflake INFORMATION_SCHEMA. However, there is a limit to the amount of data you can retrieve from INFORMATION_SCHEMA. If you run the extraction tool and receive the error SnowflakeSQLException: Information schema query returned too much data, you must take the following steps so that you can read metadata from the SNOWFLAKE.ACCOUNT_USAGE schema instead:

Open the Shares option in the Snowflake web interface.

Create a database from the SNOWFLAKE.ACCOUNT_USAGE share:

-- CREATE DATABASE database FROM SHARE SNOWFLAKE.ACCOUNT_USAGE;

Create a role:
```
CREATE ROLE role;
```

Grant IMPORTED privileges on the new database to the role:

GRANT IMPORTED PRIVILEGES ON DATABASE database TO ROLE role;

Grant the role to the user you intend to use to run the dwh-migration-dumper tool:
```
GRANT ROLE role TO USER user;
```

Vertica

To allow the dwh-migration-dumper tool to connect to Vertica, download their JDBC driver from their download page.

The following table describes the commonly used flags for extracting Vertica metadata by using the extraction tool. For information about all supported flags, see global flags.

Name	Default value	Description	Required
`--connector`		The name of the connector to use, in this case vertica.	Yes
`--database`		The name of the database to connect to.	Yes
`--driver`		The absolute or relative path to the driver JAR file to use for this connection. You can specify multiple driver JAR files, separating them by commas.	Yes
`--host`	localhost	The hostname or IP address of the database server.	No
`--password`		The password to use for the database connection.	Yes
`--port`	5433	The port of the database server.	No
`--user`		The username to use for the database connection.	Yes

Examples

The following example shows how to extract metadata from a Vertica database on the local host:

dwh-migration-dumper \
  --driver path/vertica-jdbc.jar \
  --connector vertica \
  --database database
  --user user
  --password password

Global flags

The following table describes the flags that can be used with any of the supported source platforms.

Name	Description
`--connector`	The connector name for the source system.
`--database`	Usage varies by source system.
`--driver`	The absolute or relative path to the driver JAR file to use when connecting to the source system. You can specify multiple driver JAR files, separating them by commas.
`--dry-run` or `-n`	Show what actions the extraction tool would make without executing them.
`--help`	Displays command-line help.
`--host`	The hostname or IP address of the database server to connect to.
`--jdbcDriverClass`	Optionally overrides the vendor-specified JDBC driver class name. Use this if you have a custom JDBC client.
`--output`	The path of the output zip file. For example, `dir1/dir2/teradata-metadata.zip`. If you don't specify a path, the output file is created in your working directory. If you specify the path to a directory, the default zip filename is created in the specified directory. If the directory does not exist, it is created. To use Cloud Storage, use the following format: `gs://<BUCKET>/<PATH>` To authenticate using Google Cloud credentials, see Authenticate for using client libraries.
`--password`	The password to use for the database connection.
`--port`	The port of the database server.
`--save-response-file`	Saves your command line flags in a JSON file for easy re-use. The file is named `dumper-response-file.json` and is created in the working directory. To use the response file, provide the path to it prefixed by `@` when you run the extraction tool, for example `dwh-migration-dumper @path/to/dumper-response-file.json`.
`--schema`	A list of the schemas to extract, separated by commas. Oracle doesn't differentiate between a schema and the database user who created the schema, so you can use either schema names or user names with the `--schema` flag. For example, `--schema schema1,user2,schema3`.
`--thread-pool-size`	Sets the thread pool size, which affects the connection pool size. The default size of the thread pool is the number of cores on the server running the `dwh-migration-dumper` tool. If the extraction tool seems slow or otherwise in need of more resources, you can raise the number of threads used. If there are indications that other processes on the server require more bandwidth, you can lower the number of threads used.
`--url`	The URL to use for the database connection, instead of the URI generated by the JDBC driver. The generated URI should be sufficient in most cases. Only override the generated URI when you need to use a JDBC connection setting that is specific to the source platform and is not already set by one of the flags listed in this table.
`--user`	The username to use for the database connection.
`--version`	Displays the product version.

Troubleshooting

This section explains some common issues and troubleshooting techniques for the dwh-migration-dumper tool.

Out of memory error

The java.lang.OutOfMemoryError error in the dwh-migration-dumper tool terminal output is often related to insufficient memory for processing retrieved data. To address this issue, increase available memory or reduce the number of processing threads.

You can increase maximum memory by exporting the JAVA_OPTS environment variable:

Linux

export JAVA_OPTS="-Xmx4G"

Windows

set JAVA_OPTS="-Xmx4G"

You can reduce the number of processing threads (default is 32) by including the --thread-pool-size flag. This option is supported for hiveql and redshift* connectors only.

dwh-migration-dumper --thread-pool-size=1

Handling a `WARN...Task failed` error

You might sometimes see a WARN [main] o.c.a.d.MetadataDumper [MetadataDumper.java:107] Task failed: … error in the dwh-migration-dumper tool terminal output. The extraction tool submits multiple queries to the source system, and the output of each query is written to its own file. Seeing this issue indicates that one of these queries failed. However, failure of one query doesn't prevent the execution of the other queries. If you see more than a couple of WARN errors, review the issue details and see if there is anything that you need to correct in order for the query to run appropriately. For example, if the database user you specified when running the extraction tool lacks permissions to read all metadata, try again with a user with the correct permissions.

Corrupted ZIP file

To validate the dwh-migration-dumper tool zip file, download the SHA256SUMS.txt file and run the following command:

sha256sum --check SHA256SUMS.txt

The OK result confirms successful checksum verification. Any other message indicates verification error:

FAILED: computed checksum did NOT match: the zip file is corrupted and has to be downloaded again.
FAILED: listed file could not be read: the zip file version can't be located. Make sure the checksum and zip files are downloaded from the same release version and placed in the same directory.

Teradata query logs extraction is slow

To improve performance of joining tables that are specified by the -Dteradata-logs.query-logs-table and -Dteradata-logs.sql-logs-table flags, you can include an additional column of type DATE in the JOIN condition. This column must be defined in both tables and it must be part of the Partitioned Primary Index. To include this column, use the -Dteradata-logs.log-date-column flag.

Example:

Bash

dwh-migration-dumper \
  -Dteradata-logs.query-logs-table=historicdb.ArchivedQryLogV \
  -Dteradata-logs.sql-logs-table=historicdb.ArchivedDBQLSqlTbl \
  -Dteradata-logs.log-date-column=ArchiveLogDate

Windows PowerShell

dwh-migration-dumper `
  "-Dteradata-logs.query-logs-table=historicdb.ArchivedQryLogV" `
  "-Dteradata-logs.sql-logs-table=historicdb.ArchivedDBQLSqlTbl" `
  "-Dteradata-logs.log-date-column=ArchiveLogDate"

Teradata row size limit exceeded

Teradata 15 has a 64kB row size limit. If the limit is exceeded, the dumper fails with the following message: none [Error 9804] [SQLState HY000] Response Row size or Constant Row size overflow

To resolve this error, either extend the row limit to 1MB or split the rows into multiple rows:

Install and enable the 1MB Perm and Response Rows feature and current TTU software. For more information, see Teradata Database Message 9804
Split the long query text into multiple rows by using the -Dteradata.metadata.max-text-length and -Dteradata-logs.max-sql-length flags.

The following command shows the usage of the -Dteradata.metadata.max-text-length flag to split the long query text into multiple rows of at most 10000 characters each:

Bash

dwh-migration-dumper \
  --connector teradata \
  -Dteradata.metadata.max-text-length=10000

Windows PowerShell

dwh-migration-dumper `
  --connector teradata `
  "-Dteradata.metadata.max-text-length=10000"

The following command shows the usage of the -Dteradata-logs.max-sql-length flag to split the long query text into multiple rows of at most 10000 characters each:

Bash

dwh-migration-dumper \
  --connector teradata-logs \
  -Dteradata-logs.max-sql-length=10000

Windows PowerShell

dwh-migration-dumper `
  --connector teradata-logs `
  "-Dteradata-logs.max-sql-length=10000"

What's next

After you run the dwh-migration-dumper tool, upload the output to Cloud Storage along with the source files for translation.

Generate metadata for translation and assessment

Overview

Compliance requirements

Prerequisites

Install Java

Required permissions

Install the dwh-migration-dumper tool

Run the dwh-migration-dumper tool

Teradata

Examples

Tables and views extracted by the dwh-migration-dumper tool

Redshift

Examples

Tables and views extracted by the dwh-migration-dumper tool

Apache Hive/Spark or Trino/PrestoSQL

Examples

Azure Synapse or Microsoft SQL Server

Examples

Netezza

Examples

Oracle

Examples

Snowflake

Examples

Working with large Snowflake instances

Vertica

Examples

Global flags

Troubleshooting

Out of memory error

Linux

Windows

Handling a WARN...Task failed error

Corrupted ZIP file

Teradata query logs extraction is slow

Bash

Windows PowerShell

Teradata row size limit exceeded

Bash

Windows PowerShell

Bash

Windows PowerShell

What's next

Install the `dwh-migration-dumper` tool

Run the `dwh-migration-dumper` tool

Tables and views extracted by the `dwh-migration-dumper` tool

Tables and views extracted by the `dwh-migration-dumper` tool

Handling a `WARN...Task failed` error