From: | Euler Taveira de Oliveira <euler(at)timbira(dot)com> |
---|---|
To: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Martin Pihlak <martin(dot)pihlak(at)gmail(dot)com>, Simon Riggs <simon(at)2ndQuadrant(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: reducing statistics write overhead |
Date: | 2009-01-23 04:28:03 |
Message-ID: | 49794753.90902@timbira.com |
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Lists: | pgsql-hackers |
Alvaro Herrera escreveu:
> Euler Taveira de Oliveira escribió:
>> Alvaro Herrera escreveu:
>>> This could be solved if the workers kept the whole history of tables
>>> that they have vacuumed. Currently we keep only a single table (the one
>>> being vacuumed right now). I proposed writing these history files back
>>> when workers were first implemented, but the idea was shot down before
>>> flying very far because it was way too complex (the rest of the patch
>>> was more than complex enough.) Maybe we can implement this now.
>>>
>> [I don't remember your proposal...] Isn't it just add a circular linked list
>> at AutoVacuumShmemStruct? Of course some lock mechanism needs to exist to
>> guarantee that we don't write at the same time. The size of this linked list
>> would be scale by a startup-time-guc or a reasonable fixed value.
>
> Well, the problem is precisely how to size the list. I don't like the
> idea of keeping an arbitrary number in memory; it adds another
> mostly-useless tunable that we'll need to answer questions about for all
> eternity.
>
[Poking the code a little...] You're right. We could do that but it isn't an
elegant solution. What about tracking that information at table_oids?
struct table_oids {
bool skipit; /* initially false */
Oid relid;
};
--
Euler Taveira de Oliveira
http://www.timbira.com/
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