Spanner Table Copy

Beam pipeline to run a query on a Spanner database and write the results to a spanner table.

This pipeline can be used for various functions to transform/update a database, without needing to be concerned about transaction mutation limitations

• Transforming read data using SQL and writing the results back, e.g. the equivalent of the following pseudo-sql:

  INSERT OR UPDATE INTO <table> (key, value)
  (
     SELECT key, value*100 FROM <table> WHERE <condition>
  )

• Point-in-time recovery by reading the database state at a point in the past (within the Spanner database's version retention period, and then writing it back. e.g. the equivalent of the following pseudo-sql:

  INSERT OR UPDATE INTO <table> (key, value)
  (
     SELECT key, value
     FROM <table> FOR SYSTEM_TIME AS OF <timestamp_RFC3339>
     WHERE <condition>
  )

• Copying data from one database to another, e.g. the equivalent of the following pseudo-sql:

 INSERT OR UPDATE INTO <table@project2/instance2/database2> (key, value)
 (
    SELECT key, value FROM <table@project1/instance1/database1>
 )

Usage:

Show help text:

mvn compile exec:java -Dexec.mainClass=com.google.cloud.solutions.SpannerTableCopy
    -Dexec.args='--help=com.google.cloud.solutions.SpannerTableCopy$SpannerTableCopyOptions'

Execute the pipeline:

For example copying a table at a timestamp in the past to a different database:

mvn compile exec:java
    -Dexec.mainClass=com.google.cloud.solutions.SpannerTableCopy \
    -Pdataflow-runner
    -Dexec.args="
         --runner=DataflowRunner

         --sourceProjectId=SOURCE_PROJECT
         --sourceInstanceId=SOURCE_INSTANCE
         --sourceDatabaseId=SOURCE_DATABASE

         --sqlQuery='select * from SOURCE_TABLE'
         --readTimestamp=2022-01-01T12:00:00Z

         --destinationProjectId=DEST_PROJECT
         --destinationInstanceId=DEST_INSTANCE
         --destinationDatabaseId=DEST_DATABASE
         --destinationTable=DEST_TABLE
         --writeMode=WRITE_MODE

         --mutationReportFile=gs://BUCKET/PATH/report
         --failureLogFile=gs://BUCKET/PATH/failures
    "

More examples can be found in the SpannerTableCopyIntegrationTest

Note: take care of Bash quoting with -Dexec.args and the --sqlQuery value.

The --dryRun parameter can be used to create the mutation report file without actually writing to the database.

--writeMode values correspond to the values of the Mutation.Op enum