[jira] [Created] (DRILL-7459) Fetch size does not work on Postgres JDBC plugin

["Priyanka Bhoir (Jira)" <ji...@apache.org>]

Priyanka Bhoir created DRILL-7459:
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             Summary: Fetch size does not work on Postgres JDBC plugin
                 Key: DRILL-7459
                 URL: https://issues.apache.org/jira/browse/DRILL-7459
             Project: Apache Drill
          Issue Type: Bug
          Components: Storage - JDBC
    Affects Versions: 1.15.0
            Reporter: Priyanka Bhoir


To prevent the drill from going out of memory, it is suggested to set the fetch size in Jdbc URL to enable data streaming([#DRILL-6794 | https://issues.apache.org/jira/browse/DRILL-6794] discusses this). This does not work on Postgres for the following reason:

For fetchSize size to work on Postgres, the connection must not be in autocommit mode. There is no parameter to set autocommit to false in connection string other than programmatically calling conn.setAutoCommit(false).

See [https://jdbc.postgresql.org/documentation/93/query.html#fetchsize-example]
See [https://jdbc.postgresql.org/documentation/head/connect.html] for the list of all connection string properties.

Fix is to add a property 'defaultAutoCommit' to JdbcStorageConfig and call BasicDataSource#setDefaultAutoCommit in JdbcStoragePlugin.



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