[DRILL-7459] Fetch size does not work on Postgres JDBC plugin

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.15.0
• Fix Version/s: 1.18.0
• Component/s: Storage - JDBC
• Assignee: Arina Ielchiieva
• Reporter: Priyanka Bhoir
• Created: 27/Nov/19 05:29
• Updated: 16/Mar/20 16:15
• Resolved: 03/Feb/20 17:44

Description

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 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.

Issue Links

• is part of: DRILL-7467 Jdbc plugin enhancements and fixes