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Re: another query optimization question

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: David Teran <david(dot)teran(at)cluster9(dot)com>
Cc: Stephan Szabo <sszabo(at)megazone(dot)bigpanda(dot)com>,Marc Fournier <scrappy(at)hub(dot)org>,PgSQL Performance ML <pgsql-performance(at)postgresql(dot)org>
Subject: Re: another query optimization question
Date: 2004-01-31 15:45:56
Message-ID: 3875.1075563956@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-performance
David Teran <david(dot)teran(at)cluster9(dot)com> writes:
> Apple provides a little tool that can enable / disable the l2 cache ... 
> one CPU of a dual CPU system on the fly. When i start the testapp with 
> two CPU's enabled i get this output here, when i turn off one CPU while 
> the app is still running the messages disappear as long as one CPU is 
> turned off. Reactivating the CPU again produces new error messages.

Ah-hah, so the gettimeofday bug *is* linked to multiple CPUs.  Marc,
were the machines you saw it on all multi-CPU?

> Do you remember where one can find a patch?

File a bug report with Apple.

> Do you know if this bug makes a system unusable with PostgresSQL?

Not at all.  The only bad effect we've noted is that EXPLAIN results
are sometimes wacky.  In theory you could sometimes see the result of
now() being off by a second or two, but no one's reported seeing that.

			regards, tom lane

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