Hi everyone. I'm trying to understand why load balancing doesn't work with the
PostgreSQL JDBC driver, and what (if anything) can be done about it. I have to
admit, I find the documentation a bit confusing. Here is what it currently
says at http://pgpool.projects.postgresql.org/pgpool-II/doc/pgpool-en.html:
"Note: the JDBC driver has an autocommit option. If autocommit is false,
the JDBC driver sends "BEGIN" and "COMMIT" by itself. So pgpool cannot do any
load balancing. You need to call setAutoCommit(true) to enable autocommit."
And yet, a recent post to this mailing list
(http://pgfoundry.org/pipermail/pgpool-general/2011-July/003819.html)
contradicts this, and says that recent versions of pgpool-II can handle
explicit transactions. And the flow chart
(http://pgpool.projects.postgresql.org/pgpool-II/doc/where_to_send_queries.pdf)
seems to say the same thing.
Even more confusing is the fact that it *does* seem to work once in a while.
I'm currently using pgpool-II 3.0.4, with PostgreSQL 9.0.2 in streaming
replication mode, and JDBC driver. When I enable statement logging in both
pgpool-II and PostgreSQL, I can see that a very small number queries do go to
the slave. I have not been able to figure out any pattern to this.
I would really love to understand more about what is going on. Any help would
be sincerely appreciated.
Sincerely,
Matt Solnit <[email protected]>
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