Re: Lock contention, docs vs. reality - Mailing list pgsql-general

From Tom Lane
Subject Re: Lock contention, docs vs. reality
Date
Msg-id 14289.1177303512@sss.pgh.pa.us
Whole thread Raw
In response to Lock contention, docs vs. reality  (Roland Turner <raz.cbfgterfdy.bet@raz.cx>)
List pgsql-general
Roland Turner <raz.cbfgterfdy.bet@raz.cx> writes:
> I'm working with 7.4, but the 8.2 docs[1] have the same apparent error:
> ROW SHARE

>         Conflicts with the EXCLUSIVE and ACCESS EXCLUSIVE lock modes.

> If that conflict list were correct, then ROW SHARE wouldn't conflict
> with itself, much less with ROW EXCLUSIVE (required to prevent
> INSERT/UPDATE/DELETE); commonsense dictates that it should conflict with
> both, and experiment demonstrates that it actually does so.

A moment's examination of the source code (see the conflict tables in
src/backend/storage/lmgr/lock.c) shows that the documentation claim is
correct.  Please provide your experiment to the contrary.

            regards, tom lane

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