From: John A Meinel <john@arbash-meinel.com>
To: Matthew Schumacher <matt.s@aptalaska.net>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-performance@postgresql.org
Subject: Re: Performance problems testing with Spamassassin 3.1.0
Date: Thu, 04 Aug 2005 14:36:12 -0500
Message-ID: <42F26E2C.8010607@arbash-meinel.com> (raw)
In-Reply-To: <42F251F0.1070407@aptalaska.net>
References: <42E9749F.6000709@aptalaska.net>
<1122616211.5691.340.camel@lamb.mcmillan.net.nz>
<42EA6966.8090402@aptalaska.net>
<1122668371.5691.352.camel@lamb.mcmillan.net.nz>
<19405.1122670917@sss.pgh.pa.us>
<42EAA410.9010700@aptalaska.net>
<27897.1122748133@sss.pgh.pa.us>
<42EE8043.1050207@aptalaska.net>
<op.suulgxokth1vuj@localhost>
<42EE93F8.5010003@aptalaska.net>
<20050801214931.GF60019@decibel.org>
<42EE9D83.8000405@pobox.com>
<42F1CE43.8040801@aptalaska.net>
<15610.1123166222@sss.pgh.pa.us>
<42F23FB6.5010405@aptalaska.net>
<42F251F0.1070407@aptalaska.net>
Matthew Schumacher wrote:
> Matthew Schumacher wrote:
>
>>Tom Lane wrote:
>>
>>
>>
>>>I don't really see why you think that this path is going to lead to
>>>better performance than where you were before. Manipulation of the
>>>temp table is never going to be free, and IN (sub-select) is always
>>>inherently not fast, and NOT IN (sub-select) is always inherently
>>>awful. Throwing a pile of simple queries at the problem is not
>>>necessarily the wrong way ... especially when you are doing it in
>>>plpgsql, because you've already eliminated the overhead of network
>>>round trips and repeated planning of the queries.
>>>
>>> regards, tom lane
>>
>>
>>The reason why I think this may be faster is because I would avoid
>>running an update on data that needs to be inserted which saves
>>searching though the table for a matching token.
>>
>>Perhaps I should do the insert first, then drop those tokens from the
>>temp table, then do my updates in a loop.
>>
>>I'll have to do some benchmarking...
>>
>>schu
>
>
> Tom, I think your right, whenever I do a NOT IN it does a full table
> scan against bayes_token and since that table is going to get very big
> doing the simple query in a loop that uses an index seems a bit faster.
>
> John, thanks for your help, it was worth a try, but it looks like the
> looping is just faster.
>
> Here is what I have so far in case anyone else has ideas before I
> abandon it:
Surely this isn't what you have. You have *no* loop here, and you have
stuff like:
AND
(bayes_token_tmp) NOT IN (SELECT token FROM bayes_token);
I'm guessing this isn't your last version of the function.
As far as putting the CREATE TEMP TABLE inside the function, I think the
problem is that the first time it runs, it compiles the function, and
when it gets to the UPDATE/INSERT with the temporary table name, at
compile time it hard-codes that table id.
I tried getting around it by using "EXECUTE" which worked, but it made
the function horribly slow. So I don't recommend it.
Anyway, if you want us to evaluate it, you really need to send us the
real final function.
John
=:->
>
> CREATE OR REPLACE FUNCTION put_tokens(inuserid INTEGER,
> intokenary BYTEA[],
> inspam_count INTEGER,
> inham_count INTEGER,
> inatime INTEGER)
> RETURNS VOID AS '
> DECLARE
> _token BYTEA;
> BEGIN
>
> UPDATE
> bayes_token
> SET
> spam_count = greatest_int(spam_count + inspam_count, 0),
> ham_count = greatest_int(ham_count + inham_count , 0),
> atime = greatest_int(atime, inatime)
> WHERE
> id = inuserid
> AND
> (token) IN (SELECT bayes_token_tmp FROM bayes_token_tmp(intokenary));
>
> UPDATE
> bayes_vars
> SET
> token_count = token_count + (
> SELECT
> count(bayes_token_tmp)
> FROM
> bayes_token_tmp(intokenary)
> WHERE
> bayes_token_tmp NOT IN (SELECT token FROM bayes_token)),
> newest_token_age = greatest_int(newest_token_age, inatime),
> oldest_token_age = least_int(oldest_token_age, inatime)
> WHERE
> id = inuserid;
>
> INSERT INTO
> bayes_token
> SELECT
> inuserid,
> bayes_token_tmp,
> inspam_count,
> inham_count,
> inatime
> FROM
> bayes_token_tmp(intokenary)
> WHERE
> (inspam_count > 0 OR inham_count > 0)
> AND
> (bayes_token_tmp) NOT IN (SELECT token FROM bayes_token);
>
> RETURN;
> END;
> ' LANGUAGE 'plpgsql';
>
> CREATE OR REPLACE FUNCTION bayes_token_tmp(intokenary BYTEA[]) RETURNS
> SETOF bytea AS
> '
> BEGIN
> for i in array_lower(intokenary, 1) .. array_upper(intokenary, 1)
> LOOP
> return next intokenary[i];
> END LOOP;
> RETURN;
> end
> '
> language 'plpgsql';
>
> CREATE OR REPLACE FUNCTION greatest_int (integer, integer)
> RETURNS INTEGER
> IMMUTABLE STRICT
> AS 'SELECT CASE WHEN $1 < $2 THEN $2 ELSE $1 END;'
> LANGUAGE SQL;
>
> CREATE OR REPLACE FUNCTION least_int (integer, integer)
> RETURNS INTEGER
> IMMUTABLE STRICT
> AS 'SELECT CASE WHEN $1 < $2 THEN $1 ELSE $2 END;'
> LANGUAGE SQL;
>
> ---------------------------(end of broadcast)---------------------------
> TIP 4: Have you searched our list archives?
>
> http://archives.postgresql.org
>
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To: pgsql-performance@postgresql.org
Cc: john@arbash-meinel.com, matt.s@aptalaska.net, tgl@sss.pgh.pa.us
Subject: Re: Performance problems testing with Spamassassin 3.1.0
In-Reply-To: <42F26E2C.8010607@arbash-meinel.com>
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