Re: Problem with background worker

On 20/03/2013 16:33, Alvaro Herrera wrote:
> 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.
>

Yes, that works. Thanks a lot !

Maybe this should be added to the worker_spi example ?

Regards