| From: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)2ndquadrant(dot)com> |
| Cc: | Bruce Momjian <bruce(at)momjian(dot)us>, Stephen Frost <sfrost(at)snowman(dot)net>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: MultiXactId error after upgrade to 9.3.4 |
| Date: | 2014-04-23 19:30:05 |
| Message-ID: | 20140423193005.GS25695@eldon.alvh.no-ip.org |
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| Thread: | |
| Lists: | pgsql-hackers |
Andres Freund wrote:
> I think this patch is a seriously bad idea. For one, it's not actually
> doing anything about the problem - the tuple can be accessed without
> freezing getting involved.
Normal access other than freeze is not a problem, because other code
paths do check for HEAP_XMAX_INVALID and avoid access to Xmax if that's
set.
> For another, it will increase wall traffic for freezing of short lived
> tuples considerably, without any benefit.
True. I didn't actually try to run this; it was just for demonstration
purposes. It'd need some cooperation from heap_tuple_needs_freeze in
order to work at all, for one thing.
--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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