Thread: function executes sql 100 times longer it should
Hello, list.
I have one simple SQL function returning result set that takes around 3
seconds to execute. But if I execute the Select it executes directly -
it takes only around 30 ms. Why so big difference? What should I check?
I must also say, that this started this afternoon.
PG: 8.3.3
OS: Windows Server 2003
Example below:
//========================================================================================================
CREATE OR REPLACE FUNCTION fnk_grupes_prekes(prm_pardavimo_taskas
integer, prm_grupe integer, prm_filtras character varying)
RETURNS SETOF frt_grupes_prekes AS
$BODY$SELECT DISTINCT prek_id, prek_pavadinimas, ks_kaina, mvnt_trumpinys
FROM filter_b_preke_matoma()
LEFT OUTER JOIN b_grupes_prekes ON (gp_preke=prek_id)
LEFT OUTER JOIN b_grupe ON (gp_grupe=grup_id)
JOIN b_mato_vienetai ON (mvnt_id=prek_matovnt)
JOIN b_kainorascio_sudetis ON (ks_preke = prek_id)
JOIN b_kainorascio_grafikas ON (ks_kainorastis=kag_kainorastis)
JOIN b_pardavimo_tasko_kainorastis ON (ks_kainorastis=ptk_kainorastis)
WHERE (grup_id=$2 OR $2 is Null)
AND ptk_pardavimotaskas=$1
AND ((prek_pavadinimas ILIKE ('%'||$3||'%')) OR $3 is NULL)
AND fnk_grafikas_galioja(kag_grafikas) = true
ORDER BY prek_pavadinimas
$BODY$
LANGUAGE 'sql' VOLATILE
COST 100
ROWS 1000;
ALTER FUNCTION fnk_grupes_prekes(integer, integer, character varying)
OWNER TO postgres;
GRANT EXECUTE ON FUNCTION fnk_grupes_prekes(integer, integer, character
varying) TO postgres;
GRANT EXECUTE ON FUNCTION fnk_grupes_prekes(integer, integer, character
varying) TO public;
select * from fnk_grupes_prekes(18,42,NULL);
Total query runtime: 2172 ms.
0 rows retrieved.
SELECT DISTINCT prek_id, prek_pavadinimas, ks_kaina, mvnt_trumpinys
FROM filter_b_preke_matoma()
LEFT OUTER JOIN b_grupes_prekes ON (gp_preke=prek_id)
LEFT OUTER JOIN b_grupe ON (gp_grupe=grup_id)
JOIN b_mato_vienetai ON (mvnt_id=prek_matovnt)
JOIN b_kainorascio_sudetis ON (ks_preke = prek_id)
JOIN b_kainorascio_grafikas ON (ks_kainorastis=kag_kainorastis)
JOIN b_pardavimo_tasko_kainorastis ON (ks_kainorastis=ptk_kainorastis)
WHERE (grup_id=42 OR 42 is Null)
AND ptk_pardavimotaskas=18
AND ((prek_pavadinimas ILIKE ('%'||null||'%')) OR null is NULL)
AND fnk_grafikas_galioja(kag_grafikas) = true
ORDER BY prek_pavadinimas;
Total query runtime: 47 ms.
0 rows retrieved.
--
Julius Tuskenis
Programavimo skyriaus vadovas
UAB nSoft
mob. +37068233050
On Wed, 2008-11-12 at 16:10 +0200, Julius Tuskenis wrote:
> Hello, list.
>
> I have one simple SQL function returning result set that takes around 3
> seconds to execute. But if I execute the Select it executes directly -
> it takes only around 30 ms. Why so big difference?
Probably caching the results.
> What should I check?
Explain plan might be a good start
> I must also say, that this started this afternoon.
>
> PG: 8.3.3
> OS: Windows Server 2003
>
> Example below:
> //========================================================================================================
> CREATE OR REPLACE FUNCTION fnk_grupes_prekes(prm_pardavimo_taskas
> integer, prm_grupe integer, prm_filtras character varying)
> RETURNS SETOF frt_grupes_prekes AS
> $BODY$SELECT DISTINCT prek_id, prek_pavadinimas, ks_kaina, mvnt_trumpinys
> FROM filter_b_preke_matoma()
> LEFT OUTER JOIN b_grupes_prekes ON (gp_preke=prek_id)
> LEFT OUTER JOIN b_grupe ON (gp_grupe=grup_id)
> JOIN b_mato_vienetai ON (mvnt_id=prek_matovnt)
> JOIN b_kainorascio_sudetis ON (ks_preke = prek_id)
> JOIN b_kainorascio_grafikas ON (ks_kainorastis=kag_kainorastis)
> JOIN b_pardavimo_tasko_kainorastis ON (ks_kainorastis=ptk_kainorastis)
> WHERE (grup_id=$2 OR $2 is Null)
> AND ptk_pardavimotaskas=$1
> AND ((prek_pavadinimas ILIKE ('%'||$3||'%')) OR $3 is NULL)
> AND fnk_grafikas_galioja(kag_grafikas) = true
> ORDER BY prek_pavadinimas
> $BODY$
> LANGUAGE 'sql' VOLATILE
> COST 100
> ROWS 1000;
> ALTER FUNCTION fnk_grupes_prekes(integer, integer, character varying)
> OWNER TO postgres;
> GRANT EXECUTE ON FUNCTION fnk_grupes_prekes(integer, integer, character
> varying) TO postgres;
> GRANT EXECUTE ON FUNCTION fnk_grupes_prekes(integer, integer, character
> varying) TO public;
>
>
> select * from fnk_grupes_prekes(18,42,NULL);
> Total query runtime: 2172 ms.
> 0 rows retrieved.
>
>
> SELECT DISTINCT prek_id, prek_pavadinimas, ks_kaina, mvnt_trumpinys
> FROM filter_b_preke_matoma()
> LEFT OUTER JOIN b_grupes_prekes ON (gp_preke=prek_id)
> LEFT OUTER JOIN b_grupe ON (gp_grupe=grup_id)
> JOIN b_mato_vienetai ON (mvnt_id=prek_matovnt)
> JOIN b_kainorascio_sudetis ON (ks_preke = prek_id)
> JOIN b_kainorascio_grafikas ON (ks_kainorastis=kag_kainorastis)
> JOIN b_pardavimo_tasko_kainorastis ON (ks_kainorastis=ptk_kainorastis)
> WHERE (grup_id=42 OR 42 is Null)
> AND ptk_pardavimotaskas=18
> AND ((prek_pavadinimas ILIKE ('%'||null||'%')) OR null is NULL)
> AND fnk_grafikas_galioja(kag_grafikas) = true
> ORDER BY prek_pavadinimas;
>
> Total query runtime: 47 ms.
> 0 rows retrieved.
>
First run probably put the plan and results into the query cache. The
second run could just pull it from there instead of going to the tables
on the disk.
> --
>
> Julius Tuskenis
> Programavimo skyriaus vadovas
> UAB nSoft
> mob. +37068233050
>
Attachment
Hello Sean,
> Explain plan might be a good start
Its a good start, but leads to nothing because Explain doesn't go into
the function.
EXPLAIN select * -- prek_id, prek_pavadinimas, ks_kaina, mvnt_trumpinys
from fnk_grupes_prekes(18,42,NULL);
"Function Scan on fnk_grupes_prekes (cost=0.00..25.10 rows=10 width=143)"
EXPLAIN SELECT DISTINCT prek_id, prek_pavadinimas, ks_kaina, mvnt_trumpinys
FROM filter_b_preke_matoma()
LEFT OUTER JOIN b_grupes_prekes ON (gp_preke=prek_id)
LEFT OUTER JOIN b_grupe ON (gp_grupe=grup_id)
JOIN b_mato_vienetai ON (mvnt_id=prek_matovnt)
JOIN b_kainorascio_sudetis ON (ks_preke = prek_id)
JOIN b_kainorascio_grafikas ON (ks_kainorastis=kag_kainorastis)
JOIN b_pardavimo_tasko_kainorastis ON (ks_kainorastis=ptk_kainorastis)
WHERE (grup_id=42 OR 40 is Null)
AND ptk_pardavimotaskas=18
AND ((prek_pavadinimas ILIKE ('%'||null||'%')) OR null is NULL)
AND fnk_grafikas_galioja(kag_grafikas) = true
ORDER BY prek_pavadinimas
"Unique (cost=281.89..281.91 rows=1 width=132)"
" -> Sort (cost=281.89..281.90 rows=1 width=132)"
" Sort Key: filter_b_preke_matoma.prek_pavadinimas,
filter_b_preke_matoma.prek_id, b_kainorascio_sudetis.ks_kaina,
b_mato_vienetai.mvnt_trumpinys"
" -> Nested Loop (cost=1.07..281.88 rows=1 width=132)"
" -> Nested Loop (cost=1.07..280.35 rows=1 width=136)"
" -> Nested Loop (cost=1.07..280.06 rows=1 width=144)"
" -> Nested Loop (cost=1.07..279.53 rows=1
width=140)"
" -> Nested Loop (cost=1.07..269.69
rows=1 width=133)"
" -> Hash Join (cost=1.07..264.97
rows=15 width=125)"
" Hash Cond:
(filter_b_preke_matoma.prek_matovnt = b_mato_vienetai.mvnt_id)"
" -> Function Scan on
filter_b_preke_matoma (cost=0.00..260.00 rows=1000 width=126)"
" -> Hash (cost=1.03..1.03
rows=3 width=7)"
" -> Seq Scan on
b_mato_vienetai (cost=0.00..1.03 rows=3 width=7)"
" -> Index Scan using idx_gp_preke
on b_grupes_prekes (cost=0.00..0.30 rows=1 width=8)"
" Index Cond:
(b_grupes_prekes.gp_preke = filter_b_preke_matoma.prek_id)"
" Filter:
(b_grupes_prekes.gp_grupe = 42)"
" -> Index Scan using idx_ks_preke on
b_kainorascio_sudetis (cost=0.00..9.80 rows=3 width=15)"
" Index Cond:
(b_kainorascio_sudetis.ks_preke = filter_b_preke_matoma.prek_id)"
" -> Index Scan using idx_kag_kainorastis on
b_kainorascio_grafikas (cost=0.00..0.52 rows=1 width=4)"
" Index Cond:
(b_kainorascio_grafikas.kag_kainorastis =
b_kainorascio_sudetis.ks_kainorastis)"
" Filter:
fnk_grafikas_galioja(b_kainorascio_grafikas.kag_grafikas)"
" -> Index Scan using
unq_kainorastis_pardavimo_taskui on b_pardavimo_tasko_kainorastis
(cost=0.00..0.28 rows=1 width=4)"
" Index Cond:
((b_pardavimo_tasko_kainorastis.ptk_pardavimotaskas = 18) AND
(b_pardavimo_tasko_kainorastis.ptk_kainorastis =
b_kainorascio_sudetis.ks_kainorastis))"
" -> Seq Scan on b_grupe (cost=0.00..1.52 rows=1 width=4)"
" Filter: (b_grupe.grup_id = 42)"
> First run probably put the plan and results into the query cache. The
> second run could just pull it from there instead of going to the tables
> on the disk.
>
I dont think its true, because even if I change parameter values in SQL
it still returns results fast. So my guess is that the problem is
somewhere else. Maybe theres a way to see Explain plan for function body??
--
Julius Tuskenis
Programavimo skyriaus vadovas
UAB nSoft
mob. +37068233050
Most likely, you get different plans because the function has to deal with the parametrized query, hence planner cannot effectively use statistics. For example conditions like this
WHERE (grup_id=$2 OR $2 is Null)
would prevent planner from use of index (if there is one), while with literal query they would be simplified to just
WHERE grup_id=42.
WHERE (grup_id=$2 OR $2 is Null)
would prevent planner from use of index (if there is one), while with literal query they would be simplified to just
WHERE grup_id=42.
On Thu, Nov 13, 2008 at 11:16 AM, Julius Tuskenis <julius@nsoft.lt> wrote:
It does, after a bit of street magic:
CREATE OR REPLACE FUNCTION fnk_grupes_prekes(prm_
Its a good start, but leads to nothing because Explain doesn't go into the function.
It does, after a bit of street magic:
CREATE OR REPLACE FUNCTION fnk_grupes_prekes(prm_
pardavimo_taskas integer, prm_grupe integer, prm_filtras character varying)
RETURNS refcursor AS
$BODY$
declare
cur refcursor;
begin
open cur for
explain analyze
SELECT DISTINCT prek_id, prek_pavadinimas, ks_kaina, mvnt_trumpinys
FROM filter_b_preke_matoma()
LEFT OUTER JOIN b_grupes_prekes ON (gp_preke=prek_id)
LEFT OUTER JOIN b_grupe ON (gp_grupe=grup_id)
JOIN b_mato_vienetai ON (mvnt_id=prek_matovnt)
JOIN b_kainorascio_sudetis ON (ks_preke = prek_id)
JOIN b_kainorascio_grafikas ON (ks_kainorastis=kag_kainorastis)
JOIN b_pardavimo_tasko_kainorastis ON (ks_kainorastis=ptk_kainorastis)
WHERE (grup_id=$2 OR $2 is Null)
AND ptk_pardavimotaskas=$1
AND ((prek_pavadinimas ILIKE ('%'||$3||'%')) OR $3 is NULL)
AND fnk_grafikas_galioja(kag_grafikas) = true
ORDER BY prek_pavadinimas;
return cur;
end;
$BODY$
LANGUAGE 'plpgsql' VOLATILE;
begin;
select fnk_grupes_prekes(...);
fetch all in cur;
(I didnt test the above commands, but that's what I do to debug in-function plans)
RETURNS refcursor AS
$BODY$
declare
cur refcursor;
begin
open cur for
explain analyze
SELECT DISTINCT prek_id, prek_pavadinimas, ks_kaina, mvnt_trumpinys
FROM filter_b_preke_matoma()
LEFT OUTER JOIN b_grupes_prekes ON (gp_preke=prek_id)
LEFT OUTER JOIN b_grupe ON (gp_grupe=grup_id)
JOIN b_mato_vienetai ON (mvnt_id=prek_matovnt)
JOIN b_kainorascio_sudetis ON (ks_preke = prek_id)
JOIN b_kainorascio_grafikas ON (ks_kainorastis=kag_kainorastis)
JOIN b_pardavimo_tasko_kainorastis ON (ks_kainorastis=ptk_kainorastis)
WHERE (grup_id=$2 OR $2 is Null)
AND ptk_pardavimotaskas=$1
AND ((prek_pavadinimas ILIKE ('%'||$3||'%')) OR $3 is NULL)
AND fnk_grafikas_galioja(kag_grafikas) = true
ORDER BY prek_pavadinimas;
return cur;
end;
$BODY$
LANGUAGE 'plpgsql' VOLATILE;
begin;
select fnk_grupes_prekes(...);
fetch all in cur;
(I didnt test the above commands, but that's what I do to debug in-function plans)
Thank you Vyacheslav.
your "bit or street magic" worked and now I have Execution Plans for both queries: from function and simple SQL.
I'm not good in reading and interpreting these please advice witch part should I put my attention to?
FUNCTION:
"Unique (cost=290.13..290.15 rows=1 width=132) (actual time=1834.211..1834.222 rows=2 loops=1)"
" -> Sort (cost=290.13..290.14 rows=1 width=132) (actual time=1834.207..1834.209 rows=2 loops=1)"
" Sort Key: filter_b_preke_matoma.prek_pavadinimas, filter_b_preke_matoma.prek_id,
b_kainorascio_sudetis.ks_kaina,b_mato_vienetai.mvnt_trumpinys"
" Sort Method: quicksort Memory: 17kB"
" -> Nested Loop Left Join (cost=1.03..290.12 rows=1 width=132) (actual time=374.851..1834.169 rows=2
loops=1)"
" Join Filter: (b_grupes_prekes.gp_grupe = b_grupe.grup_id)"
" Filter: ((b_grupe.grup_id = $1) OR ($1 IS NULL))"
" -> Nested Loop Left Join (cost=1.03..288.07 rows=1 width=136) (actual time=45.915..1795.235 rows=694
loops=1)"
" -> Nested Loop (cost=1.03..281.39 rows=1 width=132) (actual time=45.902..1789.018 rows=694
loops=1)"
" -> Nested Loop (cost=1.03..281.11 rows=1 width=140) (actual time=8.021..1734.222 rows=6367
loops=1)"
" -> Nested Loop (cost=1.03..280.58 rows=1 width=136) (actual time=6.618..79.367
rows=6000loops=1)"
" -> Nested Loop (cost=1.03..268.87 rows=1 width=125) (actual time=6.595..34.114
rows=2820loops=1)"
" Join Filter: (filter_b_preke_matoma.prek_matovnt =
b_mato_vienetai.mvnt_id)"
" -> 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))"
" -> Materialize (cost=1.03..1.06 rows=3 width=7) (actual
time=0.001..0.002rows=3 loops=2820)"
" -> Seq Scan on b_mato_vienetai (cost=0.00..1.03 rows=3 width=7)
(actualtime=0.005..0.009 rows=3 loops=1)"
" -> Index Scan using idx_ks_preke on b_kainorascio_sudetis (cost=0.00..11.67
rows=3width=15) (actual time=0.007..0.010 rows=2 loops=2820)"
" Index Cond: (b_kainorascio_sudetis.ks_preke =
filter_b_preke_matoma.prek_id)"
" -> Index Scan using idx_kag_kainorastis on b_kainorascio_grafikas (cost=0.00..0.52
rows=1width=4) (actual time=0.199..0.272 rows=1 loops=6000)"
" Index Cond: (b_kainorascio_grafikas.kag_kainorastis =
b_kainorascio_sudetis.ks_kainorastis)"
" Filter: fnk_grafikas_galioja(b_kainorascio_grafikas.kag_grafikas)"
" -> Index Scan using unq_kainorastis_pardavimo_taskui on b_pardavimo_tasko_kainorastis
(cost=0.00..0.28rows=1 width=4) (actual time=0.005..0.006 rows=0 loops=6367)"
" Index Cond: ((b_pardavimo_tasko_kainorastis.ptk_pardavimotaskas = $2) AND
(b_pardavimo_tasko_kainorastis.ptk_kainorastis= b_kainorascio_sudetis.ks_kainorastis))"
" -> Index Scan using idx_gp_preke on b_grupes_prekes (cost=0.00..6.67 rows=1 width=8) (actual
time=0.006..0.006rows=0 loops=694)"
" Index Cond: (b_grupes_prekes.gp_preke = filter_b_preke_matoma.prek_id)"
" -> Seq Scan on b_grupe (cost=0.00..1.42 rows=42 width=4) (actual time=0.004..0.023 rows=42 loops=694)"
"Total runtime: 1834.686 ms"
SIMPLE SQL:
"Unique (cost=281.91..281.93 rows=1 width=132) (actual time=34.438..34.447 rows=2 loops=1)"
" -> Sort (cost=281.91..281.92 rows=1 width=132) (actual time=34.435..34.436 rows=2 loops=1)"
" Sort Key: filter_b_preke_matoma.prek_pavadinimas, filter_b_preke_matoma.prek_id,
b_kainorascio_sudetis.ks_kaina,b_mato_vienetai.mvnt_trumpinys"
" Sort Method: quicksort Memory: 17kB"
" -> Nested Loop (cost=1.07..281.90 rows=1 width=132) (actual time=15.226..34.396 rows=2 loops=1)"
" -> Nested Loop (cost=1.07..280.37 rows=1 width=136) (actual time=15.197..34.331 rows=2 loops=1)"
" -> Nested Loop (cost=1.07..280.08 rows=1 width=144) (actual time=13.976..34.233 rows=7 loops=1)"
" -> Nested Loop (cost=1.07..279.55 rows=1 width=140) (actual time=12.178..29.760 rows=7
loops=1)"
" -> Nested Loop (cost=1.07..269.69 rows=1 width=133) (actual time=12.165..29.700
rows=2loops=1)"
" -> Hash Join (cost=1.07..264.97 rows=15 width=125) (actual time=6.452..13.617
rows=2820loops=1)"
" Hash Cond: (filter_b_preke_matoma.prek_matovnt = b_mato_vienetai.mvnt_id)"
" -> Function Scan on filter_b_preke_matoma (cost=0.00..260.00 rows=1000
width=126)(actual time=6.418..7.828 rows=2820 loops=1)"
" -> Hash (cost=1.03..1.03 rows=3 width=7) (actual time=0.013..0.013
rows=3loops=1)"
" -> Seq Scan on b_mato_vienetai (cost=0.00..1.03 rows=3 width=7)
(actualtime=0.005..0.007 rows=3 loops=1)"
" -> Index Scan using idx_gp_preke on b_grupes_prekes (cost=0.00..0.30 rows=1
width=8)(actual time=0.004..0.004 rows=0 loops=2820)"
" Index Cond: (b_grupes_prekes.gp_preke = filter_b_preke_matoma.prek_id)"
" Filter: (b_grupes_prekes.gp_grupe = 43)"
" -> Index Scan using idx_ks_preke on b_kainorascio_sudetis (cost=0.00..9.82 rows=3
width=15)(actual time=0.009..0.019 rows=4 loops=2)"
" Index Cond: (b_kainorascio_sudetis.ks_preke = filter_b_preke_matoma.prek_id)"
" -> Index Scan using idx_kag_kainorastis on b_kainorascio_grafikas (cost=0.00..0.52 rows=1
width=4)(actual time=0.536..0.634 rows=1 loops=7)"
" Index Cond: (b_kainorascio_grafikas.kag_kainorastis =
b_kainorascio_sudetis.ks_kainorastis)"
" Filter: fnk_grafikas_galioja(b_kainorascio_grafikas.kag_grafikas)"
" -> Index Scan using unq_kainorastis_pardavimo_taskui on b_pardavimo_tasko_kainorastis
(cost=0.00..0.28rows=1 width=4) (actual time=0.009..0.009 rows=0 loops=7)"
" Index Cond: ((b_pardavimo_tasko_kainorastis.ptk_pardavimotaskas = 18) AND
(b_pardavimo_tasko_kainorastis.ptk_kainorastis= b_kainorascio_sudetis.ks_kainorastis))"
" -> Seq Scan on b_grupe (cost=0.00..1.52 rows=1 width=4) (actual time=0.012..0.020 rows=1 loops=2)"
" Filter: (b_grupe.grup_id = 43)"
"Total runtime: 34.804 ms"
Vyacheslav Kalinin rašė:
> Most likely, you get different plans because the function has to deal with the parametrized query, hence planner
cannoteffectively use statistics. For example conditions like this
> WHERE (grup_id=$2 OR $2 is Null)
> would prevent planner from use of index (if there is one), while with literal query they would be simplified to just
> WHERE grup_id=42.
>
> On Thu, Nov 13, 2008 at 11:16 AM, Julius Tuskenis <julius@nsoft.lt <mailto:julius@nsoft.lt>> wrote:
>
> Its a good start, but leads to nothing because Explain doesn't go into the function.
>
> It does, after a bit of street magic:
> CREATE OR REPLACE FUNCTION fnk_grupes_prekes(prm_
> pardavimo_taskas integer, prm_grupe integer, prm_filtras character varying)
> RETURNS refcursor AS
> $BODY$
> declare
> cur refcursor;
> begin
> open cur for
> explain analyze
> SELECT DISTINCT prek_id, prek_pavadinimas, ks_kaina, mvnt_trumpinys
> FROM filter_b_preke_matoma()
> LEFT OUTER JOIN b_grupes_prekes ON (gp_preke=prek_id)
> LEFT OUTER JOIN b_grupe ON (gp_grupe=grup_id)
> JOIN b_mato_vienetai ON (mvnt_id=prek_matovnt)
> JOIN b_kainorascio_sudetis ON (ks_preke = prek_id)
> JOIN b_kainorascio_grafikas ON (ks_kainorastis=kag_kainorastis)
> JOIN b_pardavimo_tasko_kainorastis ON (ks_kainorastis=ptk_kainorastis)
> WHERE (grup_id=$2 OR $2 is Null)
> AND ptk_pardavimotaskas=$1
> AND ((prek_pavadinimas ILIKE ('%'||$3||'%')) OR $3 is NULL)
> AND fnk_grafikas_galioja(kag_grafikas) = true
> ORDER BY prek_pavadinimas;
> return cur;
> end;
> $BODY$
> LANGUAGE 'plpgsql' VOLATILE;
> begin;
> select fnk_grupes_prekes(...);
> fetch all in cur;
> (I didnt test the above commands, but that's what I do to debug in-function plans)
>
>
>
--
Julius Tuskenis
Programavimo skyriaus vadovas
UAB nSoft
mob. +37068233050
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.
> -> 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.
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