| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Peter Geoghegan <pg(at)heroku(dot)com> |
| Cc: | Jim Nasby <jim(at)nasby(dot)net>, Robert Haas <robertmhaas(at)gmail(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, Merlin Moncure <mmoncure(at)gmail(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Clock sweep not caching enough B-Tree leaf pages? |
| Date: | 2014-04-22 00:50:20 |
| Message-ID: | 9843.1398127820@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Peter Geoghegan <pg(at)heroku(dot)com> writes:
> On Mon, Apr 21, 2014 at 5:28 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> We used to have one. It was a big bottleneck --- and this was years
>> ago, when the buffer manager was much less scalable than it is today.
>> (IIRC, getting rid of a central lock was one of the main advantages
>> of the current clock sweep code over its predecessor.)
> Yes, it was. This is a major advantage of clock sweep, and anything
> that replaces it will need to maintain the same advantage. Didn't
> someone indicate that clock sweep could beat ARC around that time,
> presumably for this reason? If no one did, then my reading of a
> variety of other papers on caching indicates that this is probably the
> case.
ARC *was* the predecessor algorithm. See commit 5d5087363.
regards, tom lane
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