[PATCH] Make sure all statistics is sent after a few DML are performed

Hi,

After a DML is perfomed, the statistics is sent to pgstat by pgsent_report_sent().
However, the mininum time between stas file update is PGSTAT_STAT_INTERVAL, so if
a few DMLs are performed with short interval, some statistics could not be sent
until the backend is shutdown.

This is not a problem in usual cases, but in case that a session is remained in
idle for a long time, for example when using connection pooling, statistics of
a huge change of a table is not sent for a long time, and as a result, starting
autovacuum might be delayed.

An idea to resolve this is call pgsent_report_sent() again with a delay
after the last DML to make sure to send the statistics. The attached patch
implements this.

Any comments would be appreciated.

Regards,

--
Yugo Nagata <nagata(at)sraoss(dot)co(dot)jp>