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List:       postgresql-general
Subject:    Re: [GENERAL] demystifying nested loop vs. merge join query plan choice
From:       Tom Lane <tgl () sss ! pgh ! pa ! us>
Date:       2013-07-31 19:55:44
Message-ID: 8099.1375300544 () sss ! pgh ! pa ! us
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Sandeep Gupta <gupta.sandeep@gmail.com> writes:
> details regarding buffer usage:
> [ 100% buffer hit rate ]

Your database is evidently fully cached in memory.  If that's the
operating mode you expect, you need to change the planner's cost
parameters, in particular reduce random_page_cost to equal seq_page_cost.
There is plenty of material about this on the PG wiki or in the
pgsql-performance archives.

			regards, tom lane


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