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Re: Order of operations in lazy_vacuum_rel

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
Cc: Heikki Linnakangas <heikki(at)enterprisedb(dot)com>, pgsql-hackers(at)postgreSQL(dot)org
Subject: Re: Order of operations in lazy_vacuum_rel
Date: 2010-02-09 01:32:46
Message-ID: 4483.1265679166@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Alvaro Herrera <alvherre(at)commandprompt(dot)com> writes:
> Tom Lane wrote:
>> Actually, after thinking about this some more, I realize that this code
>> has got a significantly bigger problem than just whether it will respond
>> to CANCEL promptly.

> Err, that problem was exactly why I added the interrupt holdoff in
> there, so if you've got a better/more invasive solution, it's very
> welcome.

Well, that's a pretty incomplete solution :-(.  Maybe we should do
something about this.  There wasn't any obvious solution before,
but now that we have the nontransactional smgr-level sinval messages
being sent on drops and truncates, it seems like tying rd_targblock
clearing to those would fix the problem.  The easiest way to do that
would involve moving rd_targblock down to the SMgrRelation struct.
Probably rd_fsm_nblocks and rd_vm_nblocks too.  Comments?

			regards, tom lane

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Subject: Re: Order of operations in lazy_vacuum_rel
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