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/
PostgreSQL Development, 24x7 Support, Training & Services
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