Re: Problem with background worker

Marc Cousin escribió:
> Hi,
>
> I'm trying to write a background writer, and I'm facing a problem with
> timestamps. The following code is where I'm having a problem (it's just a demo for
> the problem):
>
> BackgroundWorkerInitializeConnection("test", NULL);
> while (!got_sigterm)
> {
>     int ret;
>     /* Wait 1s */
>     ret = WaitLatch(&MyProc->procLatch,
>     WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
>     1000L);
>     ResetLatch(&MyProc->procLatch);
>     /* Insert dummy for now */
>     StartTransactionCommand();
>     SPI_connect();
>     PushActiveSnapshot(GetTransactionSnapshot());
>     ret = SPI_execute("INSERT INTO log VALUES (now(),statement_timestamp(),clock_timestamp())", false, 0);
>     SPI_finish();
>     PopActiveSnapshot();
>     CommitTransactionCommand();
> }

Ah.  The reason for this problem is that the statement start time (which
also sets the transaction start time, when it's the first statement) is
set by postgres.c, not the transaction-control functions in xact.c.  So
you'd need to add a SetCurrentStatementStartTimestamp() call somewhere
in your loop.

--
Álvaro Herrera                http://www.2ndQuadrant.com/
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