Bulk fetch all columns from all tables in JDBC connectors #22241
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Before this change, when listing table columns, JDBC connectors would first list tables and then list columns of a table. Thus, when serving Trino's `information_schema.columns` or `system.jdbc.columns`, we would make O(#tables) calls to the remote database. With this change, we utilize remote database's bulk column listing facilities to satisfy Trino's bulk column listing requests. This can be viewed as "`information_schema.columns` pass-through", although this works for both Trino's `information_schema.columns` and Trino's `system.jdbc.columns` (`io.trino.jdbc.TrinoDatabaseMetaData.getColumns`), and does not use remote database's `information_schema.columns` directly. Instead, the commit leverages the fact that `DatabaseMetaData.getColumns` typically used to get columns of a table can be used without a table filter, and then it gets all columns from all tables. The bulk retrieval is supported for selected JDBC connectors, and by default is not supported (requires `JdbcClient` changes). Co-authored-by: Ashhar Hasan <[email protected]>
findepi
approved these changes
Jun 3, 2024
ebyhr
approved these changes
Jun 3, 2024
This was referenced Jun 5, 2024
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Description
Before this change, when listing table columns, JDBC connectors would first list tables and then list columns of a table. Thus, when serving Trino's
information_schema.columnsorsystem.jdbc.columns, we would make O(#tables) calls to the remote database.With this change, we utilize remote database's bulk column listing facilities to satisfy Trino's bulk column listing requests. This can be viewed as "
information_schema.columnspass-through", although this works for both Trino'sinformation_schema.columnsand Trino'ssystem.jdbc.columns(
io.trino.jdbc.TrinoDatabaseMetaData.getColumns), and does not use remote database'sinformation_schema.columnsdirectly. Instead, the commit leverages the fact thatDatabaseMetaData.getColumnstypically used to get columns of a table can be used without a table filter, and then it gets all columns from all tables.The bulk retrieval is supported for selected JDBC connectors, and by default is not supported (requires
JdbcClientchanges).Release notes
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