| From: | Andres Freund <andres(at)2ndquadrant(dot)com> |
|---|---|
| To: | Kevin Grittner <kgrittn(at)ymail(dot)com> |
| Cc: | Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgreSQL(dot)org> |
| Subject: | Re: SSI freezing bug |
| Date: | 2013-10-01 14:43:45 |
| Message-ID: | 20131001144345.GC3001247@alap2.anarazel.de |
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| Lists: | pgsql-hackers |
On 2013-10-01 07:41:46 -0700, Kevin Grittner wrote:
> Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
>
> > A better solution probably is to promote tuple-level locks if
> > they exist to a relation level one upon freezing I guess?
>
> It would be sufficient to promote the tuple lock to a page lock.
> It would be pretty easy to add a function to predicate.c which
> would accept a Relation and HeapTuple, check for a predicate lock
> for the tuple, and add a page lock if found (which will
> automatically clear the tuple lock). This new function would be
> called when a tuple was chosen for freezing. Since freezing always
> causes WAL-logging and disk I/O, the cost of a couple hash table
> operations should not be noticeable.
Yea, not sure why I was thinking of table level locks.
> This seems like a bug fix which should be back-patched to 9.1, yes?
Yes.
Greetings,
Andres Freund
--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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