| From: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
|---|---|
| To: | Fabrízio de Royes Mello <fabriziomello(at)gmail(dot)com> |
| Cc: | Noah Misch <noah(at)leadboat(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com>, Pgsql Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Doubt about AccessExclusiveLock in ALTER TABLE .. SET ( .. ); |
| Date: | 2015-04-06 03:53:41 |
| Message-ID: | 20150406035341.GB4369@alvh.no-ip.org |
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| Lists: | pgsql-hackers |
Fabrízio de Royes Mello wrote:
> Ok guys. The attached patch refactor the reloptions adding a new field
> "lockmode" in "relopt_gen" struct and a new method to determine the
> required lock level from an option list.
>
> We need determine the appropriate lock level for each reloption:
I don't think AccessShareLock is appropriate for any option change. You
should be using a lock level that's self-conflicting, as a minimum
requirement, to avoid two processes changing the value concurrently. (I
would probably go as far as ensuring that the lock level specified in
the table DoLockModesConflict() with itself in an Assert somewhere.)
--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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