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Re: gprof SELECT COUNT(*) results
- From: Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au>
- To: Simon Riggs <simon(at)2ndquadrant(dot)com>
- Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Qingqing Zhou <zhouqq(at)cs(dot)toronto(dot)edu>, pgsql-hackers(at)postgresql(dot)org
- Subject: Re: gprof SELECT COUNT(*) results
- Date: Sun, 27 Nov 2005 17:59:09 +0800
- Message-id: <4389836D(dot)8070501(at)familyhealth(dot)com(dot)au>
Thinking more about other systems, ISTM that Oracle can do this, as can any MVCC based system. OTOH DB2 and SQLServer take block level read locks, so they can do this too, but at major loss of concurrency and threat of deadlock. Having said that, *any* system that chose not to do this would be severely sub-optimal with buffer manager contention. So AFAICS they all need this optimization.
MySQL/Innodb would presumably do it also I wonder... Chris
- References:
- gprof SELECT COUNT(*) results
- From: Qingqing Zhou
- Re: gprof SELECT COUNT(*) results
- From: Simon Riggs
- Re: gprof SELECT COUNT(*) results
- From: Qingqing Zhou
- Re: gprof SELECT COUNT(*) results
- From: Tom Lane
- Re: gprof SELECT COUNT(*) results
- From: Simon Riggs
- Re: gprof SELECT COUNT(*) results
- From: Tom Lane
- Re: gprof SELECT COUNT(*) results
- From: Qingqing Zhou
- Re: gprof SELECT COUNT(*) results
- From: Simon Riggs
- Re: gprof SELECT COUNT(*) results
- From: Christopher Kings-Lynne
- Re: gprof SELECT COUNT(*) results
- From: Tom Lane
- Re: gprof SELECT COUNT(*) results
- From: Simon Riggs
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