| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
| Cc: | Sergey Koposov <koposov(at)ast(dot)cam(dot)ac(dot)uk>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: slow dropping of tables, DropRelFileNodeBuffers, tas |
| Date: | 2012-06-07 16:34:01 |
| Message-ID: | 10048.1339086841@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
> On 7 June 2012 14:56, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Say what? That's a performance result and proves not a damn thing about
>> safety.
> Of course not.
> Based on the rationale explained in the code comments in the patch, it
> seems like a reasonable thing to me now.
> The argument was that since we hold AccessExclusiveLock on the
> relation, no other agent can be reading in new parts of the table into
> new buffers, so the only change to a buffer would be away from the
> dropping relation, in which case we wouldn't care. Which seems correct
> to me.
Oh, I must be confused about which patch we are talking about --- I
thought this was in reference to some of the WIP ideas that were being
thrown about with respect to using lock-free access primitives. Which
patch are you proposing for commit now, exactly?
regards, tom lane
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