SELECT FOR SHARE

From: "Ilja Golshtein" <ilejn(at)yandex(dot)ru>
To: pgsql-general(at)postgresql(dot)org
Subject: SELECT FOR SHARE
Date: 2005-10-07 07:35:28
Message-ID: 43462540.000001.02943@ariel.yandex.ru
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Hello!

I'm interested in SELECT ... FOR SHARE 8.1 feature. I'd tried to measure performance degradation and got something about 30-60% for queries retrieve a lot of rows. Is it realistic estimation? Does this penalty depend on something (data types, triggers, foreign keys, whatever) significantly? Is any sort of lock escalation [and other unpreditable things] involved here?

Last question. What about ISOLATION LEVEL REPEATABLE READ syntax since non-exclusive locking for all SELECTs means [as far as I understand] nothing but REPEATABLE READ?

Thanks.

--
Best regards
Ilja Golshtein

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