Re: R: [GENERAL] Postgres 9.6.1 big slowdown by upgrading 8.4.22 - Mailing list pgsql-general

On 01/08/2017 07:30 AM, Job wrote:
> Hi, here it is, excuse me for the delay:
>
> select * from webrecord
> left join grucategorie on grucategorie.codcategoria=webrecord.categoria and grucategorie.codgruppo='f50132'
> left join grulist on grulist.nome=webrecord.dominio and grulist.codgruppo='f50132' and grulist.stato in (1,2)
> left join listef_geo_reject on listef_geo_reject.country=webrecord.country and listef_geo_reject.codgruppo='f50132'
> where dominio='PATTERN' and (grulist.stato='1' OR grucategorie.codcategoria is not null OR listef_geo_reject.country
isnot null) and (stato != 2 or stato is null); 
>
> flashstart=# explain analyze select * from webrecord
> left join grucategorie on grucategorie.codcategoria=webrecord.categoria and grucategorie.codgruppo='f50132'
> left join grulist on grulist.nome=webrecord.dominio and grulist.codgruppo='f50132' and grulist.stato in (1,2)
> left join listef_geo_reject on listef_geo_reject.country=webrecord.country and listef_geo_reject.codgruppo='f50132'
> where dominio='PATTERN' and (grulist.stato='1' OR grucategorie.codcategoria is not null OR listef_geo_reject.country
isnot null) and (stato != 2 or stato is null); 


First this is a change in query from your original post, so see Tom's post for recommendation on
how to deal with your original problem.

Second just a quick glance seems to indicate that the other filters get the number of rows down
to 1 or 2 so there does not seem to be any need to do an index scan on
grulist.stato(assuming that the plain stato is a reference to grulist.stato)

Then there is this:

left join grulist on grulist.nome=webrecord.dominio and grulist.codgruppo='f50132' and grulist.stato in (1,2)

...
and (grulist.stato='1' OR grucategorie.codcategoria is not null OR listef_geo_reject.country is not null) and (stato !=
2or stato is null) 

Caveats, it is morning here and coffee is still brewing, but I am not following. The left join limits grulist.stato to
NULL,1, 2. Your first  
condition catches the 1 value. Should not the second 'and' be (stato = 2 or stato is null). In fact I do not see why it
needsto exist at all, which 
seems to be borne out by your experimentation.

>                                                                            QUERY PLAN
>
-----------------------------------------------------------------------------------------------------------------------------------------------------------------
>  Nested Loop Left Join  (cost=246.29..801.33 rows=2 width=260) (actual time=0.364..0.364 rows=0 loops=1)
>    Filter: ((grulist.stato = '1'::numeric) OR (grucategorie.codcategoria IS NOT NULL) OR (listef_geo_reject.country
ISNOT NULL)) 
>    ->  Nested Loop Left Join  (cost=164.84..558.37 rows=2 width=241) (actual time=0.364..0.364 rows=0 loops=1)
>          Join Filter: ((grulist.nome)::text = (webrecord.dominio)::text)
>          Filter: ((grulist.stato <> '2'::numeric) OR (grulist.stato IS NULL))
>          Rows Removed by Filter: 1
>          ->  Nested Loop Left Join  (cost=124.54..448.46 rows=2 width=103) (actual time=0.297..0.299 rows=1 loops=1)
>                ->  Index Scan using dominio_idx on webrecord  (cost=0.56..120.46 rows=2 width=74) (actual
time=0.050..0.051rows=1 loops=1) 
>                      Index Cond: ((dominio)::text = 'PATTERN'::text)
>                ->  Bitmap Heap Scan on grucategorie  (cost=123.98..163.99 rows=1 width=29) (actual time=0.243..0.243
rows=1loops=1) 
>                      Recheck Cond: (((codgruppo)::text = 'f50132'::text) AND ((codcategoria)::text =
(webrecord.categoria)::text))
>                      Heap Blocks: exact=3
>                      ->  BitmapAnd  (cost=123.98..123.98 rows=1 width=0) (actual time=0.230..0.230 rows=0 loops=1)
>                            ->  Bitmap Index Scan on grucategorie_codgruppo_idx  (cost=0.00..40.39 rows=14 width=0)
(actualtime=0.035..0.035 rows=135 loops=1) 
>                                  Index Cond: ((codgruppo)::text = 'f50132'::text)
>                            ->  Bitmap Index Scan on grucategorie_categoria_idx  (cost=0.00..83.33 rows=406 width=0)
(actualtime=0.187..0.187 rows=1579 loops=1) 
>                                  Index Cond: ((codcategoria)::text = (webrecord.categoria)::text)
>          ->  Materialize  (cost=40.30..109.87 rows=1 width=138) (actual time=0.051..0.051 rows=1 loops=1)
>                ->  Bitmap Heap Scan on grulist  (cost=40.30..109.87 rows=1 width=138) (actual time=0.047..0.047
rows=1loops=1) 
>                      Recheck Cond: ((nome)::text = 'PATTERN'::text)
>                      Filter: ((stato = ANY ('{1,2}'::numeric[])) AND ((codgruppo)::text = 'f50132'::text))
>                      Rows Removed by Filter: 1
>                      Heap Blocks: exact=2
>                      ->  Bitmap Index Scan on grulist_nome_idx  (cost=0.00..40.30 rows=2 width=0) (actual
time=0.021..0.021rows=2 loops=1) 
>                            Index Cond: ((nome)::text = 'PATTERN'::text)
>    ->  Bitmap Heap Scan on listef_geo_reject  (cost=81.46..121.47 rows=1 width=19) (never executed)
>          Recheck Cond: (((codgruppo)::text = 'f50132'::text) AND ((country)::text = (webrecord.country)::text))
>          ->  BitmapAnd  (cost=81.46..81.46 rows=1 width=0) (never executed)
>                ->  Bitmap Index Scan on listef_reject_codgruppo_idx  (cost=0.00..40.44 rows=21 width=0) (never
executed)
>                      Index Cond: ((codgruppo)::text = 'f50132'::text)
>                ->  Bitmap Index Scan on listef_reject_country_idx  (cost=0.00..40.76 rows=63 width=0) (never
executed)
>                      Index Cond: ((country)::text = (webrecord.country)::text)
>  Planning time: 0.881 ms
>  Execution time: 0.510 ms
>


--
Adrian Klaver
adrian.klaver@aklaver.com