From: Julius Tuskenis <julius@nsoft.lt>
To: pgsql-admin@postgresql.org <pgsql-admin@postgresql.org>
Subject: Re: function executes sql 100 times longer it should
Date: Fri, 14 Nov 2008 14:37:23 +0200
Message-ID: <491D7103.7000105@nsoft.lt> (raw)
In-Reply-To: <9b1af80e0811130744o7421d79bue68d58b04167a929@mail.gmail.com>
References: <491AE3F2.601@nsoft.lt>
<1226500247.2221.2.camel@lin-it1.eaglepress.local>
<491BE279.50702@nsoft.lt>
<9b1af80e0811130345o37666c5dob841d93954826357@mail.gmail.com>
<491C2BA5.7080401@nsoft.lt>
<9b1af80e0811130744o7421d79bue68d58b04167a929@mail.gmail.com>
once again - thank you Vyacheslav for your quick answer.
I have to ask you one more question - is it possible to make a planer
act according to passed parameters, or is the plan predefined on
creating the function?
Vyacheslav Kalinin rašė:
> Apparently your problem starts here:
>
> > -> Function Scan on filter_b_preke_matoma (cost=0.00..267.50
> rows=5 width=126) (actual time=6.580..11.766 rows=2820 loops=1)
> > Filter:
> (((prek_pavadinimas)::text ~~* (('%'::text || ($3)::text) ||
> '%'::text)) OR ($3 IS NULL))
>
> Planner expects to see only somewhat 5 rows after function scan with
> the filter but get ~3000, which is not a surprise if one looks at your
> plain SQL query, corresponding WHERE part:
>
> AND ((prek_pavadinimas ILIKE ('%'||null||'%')) OR null is NULL)
>
> As I mentioned conditions like this get wrapped (to TRUE in your
> case), so with plain SQL planner does not even try to estimate ILIKE
> filter effect.
>
>
--
Julius Tuskenis
Programavimo skyriaus vadovas
UAB nSoft
mob. +37068233050
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Subject: Re: function executes sql 100 times longer it should
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