AW: [HACKERS] Some notes on optimizer cost estimates

From: Zeugswetter Andreas SB <ZeugswetterA(at)wien(dot)spardat(dot)at>
To: "'Tom Lane'" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "'pgsql-hackers(at)postgreSQL(dot)org'" <pgsql-hackers(at)postgreSQL(dot)org>
Subject: AW: [HACKERS] Some notes on optimizer cost estimates
Date: 2000-01-24 09:47:23
Message-ID: 219F68D65015D011A8E000006F8590C603FDC214@sdexcsrv1.f000.d0188.sd.spardat.at
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> As best I can measure on my hardware, the cost of a nonsequential
> disk read should be estimated at 4 to 5 times the cost of a sequential
> one ---

Same experience here with RS6000 AIX hardware.
450k/s random versus 4Mb/s sequential (16kb block readahead)
Compared with 256kb readahead the factor is even worse.
Like 10Mb/s sequential.

Andreas

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