Re: Clock sweep not caching enough B-Tree leaf pages?
Tom Lane <tgl@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
To: Peter Geoghegan <pg@heroku.com>
Cc: Jim Nasby <jim@nasby.net>, Robert Haas <robertmhaas@gmail.com>,
Andres Freund <andres@2ndquadrant.com>,
Merlin Moncure <mmoncure@gmail.com>,
Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2014-04-22T00:50:20Z
Lists: pgsql-hackers
Peter Geoghegan <pg@heroku.com> writes: > On Mon, Apr 21, 2014 at 5:28 PM, Tom Lane <tgl@sss.pgh.pa.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
Commits
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Replace the BufMgrLock with separate locks on the lookup hashtable and
- 5d5087363d7c 8.1.0 cited