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Re: Random plan selection in DBT-3

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: ITAGAKI Takahiro <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Random plan selection in DBT-3
Date: 2008-01-07 03:26:42
Message-ID: 2583.1199676402@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers
ITAGAKI Takahiro <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp> writes:
> There might be regularity in the plan selection. When I connect to postgres
> newly, I see plans { A, B, A, A ... }. Then disconnect, re-connect and send
> the same EXPLAINs, the same pattern was reproduced.

Hmph ... maybe some effect associated with loading up the backend's
internal caches?  I can't imagine what though.

Please see if you can extract a more self-contained test case.

			regards, tom lane

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