Re: question on index access - Mailing list pgsql-hackers

From Tom Lane
Subject Re: question on index access
Date
Msg-id 6281.1016234627@sss.pgh.pa.us
Whole thread Raw
In response to question on index access  (Neil Conway <nconway@klamath.dyndns.org>)
Responses Re: question on index access  (Neil Conway <nconway@klamath.dyndns.org>)
List pgsql-hackers
Neil Conway <nconway@klamath.dyndns.org> writes:
> AFAIK, current Postgres behavior when processing SELECT queries is like
> this:
>     (1) for each tuple in the result set, try to get an
>             AccessShareLock on it

Uh, no.  There are no per-tuple locks, other than SELECT FOR UPDATE
which doesn't affect SELECT at all.  AccessShareLock is taken on the
entire table, mainly as a means of ensuring the table doesn't disappear
from under us.
        regards, tom lane


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