Re: Synchronized Scan update

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Jeff Davis <pgsql(at)j-davis(dot)com>
Cc: Simon Riggs <simon(at)2ndquadrant(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Synchronized Scan update
Date: 2007-03-13 16:53:32
Message-ID: 3631.1173804812@sss.pgh.pa.us
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Jeff Davis <pgsql(at)j-davis(dot)com> writes:
> I agree that ss_report_loc() doesn't need to report on every call. If
> there's any significant overhead I agree that it should report less
> often. Do you think that the overhead is significant on such a simple
> function?

One extra LWLock cycle per page processed definitely *is* a significant
overhead ... can you say "context swap storm"? I'd think about doing it
once every 100 or so pages.

regards, tom lane

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