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List:       postgresql-general
Subject:    Re: [GENERAL] Large tables, ORDER BY and sequence/index scans
From:       Milan Zamazal <pdm () brailcom ! org>
Date:       2010-01-05 20:05:48
Message-ID: 87skak2u77.fsf () blackbird ! nest ! zamazal ! org
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>>>>> "JRP" == John R Pierce <pierce@hogranch.com> writes:

    >> effective_cache_size = 128MB

    JRP> thats rather small unless your systme is very memory
    JRP> constrained.  assuming postgres is the primary disk IO consumer
    JRP> on this ysstem, take a look at the cached' value on TOP or
    JRP> whatever after its been running, thats a good first order
    JRP> estimate of effective_cache_size.... this is often half or more
    JRP> of your physical memory.

Indeed, increasing effective_cache_size helps, thanks.

Thank you all for the tips, I hope I understand the planner behavior for
my queries better now.

Regards,
Milan Zamazal


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