[jira] [Created] (BEAM-12044) JdbcIO should explicitly setAutoCommit to false

[Jira]

Sylvain Veyrié created BEAM-12044:
-------------------------------------

             Summary: 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


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/dev@beam.apache.org/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, 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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