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https://issues.apache.org/jira/browse/BEAM-12044?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17308870#comment-17308870
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Eugene Kirpichov commented on BEAM-12044:
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[~aromanenko] my take: it is possible, but I think Sylvain's PR improves the
default behavior for all users, so we should do it by default. Because this is
in JdbcIO.read(), there are no commits happening anyway, so this should be
purely a performance improvement with no semantic changes.
Actually there's one possible caveat that I'll mention on the PR in a moment.
> JdbcIO should explicitly setAutoCommit to false
> -----------------------------------------------
>
> Key: BEAM-12044
> URL: https://issues.apache.org/jira/browse/BEAM-12044
> Project: Beam
> Issue Type: Bug
> Components: sdk-java-core
> Affects Versions: 2.28.0
> Reporter: Sylvain Veyrié
> Priority: P2
> Time Spent: 50m
> Remaining Estimate: 0h
>
> Hello,
> Per [PostgreSQL JDBC
> documentation|https://jdbc.postgresql.org/documentation/head/query.html#query-with-cursor],
> autocommit must be explicitly disabled on the connection to allow cursor
> streaming.
> [~jkff] mentionned it [on the mailing
> list|https://www.mail-archive.com/[email protected]/msg16808.html], however
> even if there is:
> {code:java}
> poolableConnectionFactory.setDefaultAutoCommit(false);
> {code}
> in JdbcIO:1555, currently, at least with JDBC driver 42.2.16, any read with
> JdbcIO will memoize the whole dataset (which leads to OOM), since
> {code:java}
> connection.getAutoCommit()
> {code}
> returns true in JdbcIO#ReadFn#processElement.
> I can provide a PR — the patch is pretty simple (and solves the problem for
> us in 2.28.0):
> {code:java}
> if (connection == null) {
> connection = dataSource.getConnection();
> }
> connection.setAutoCommit(false); // line added
> {code}
> Thanks!
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