1 октября 2017 г. 12:42:14 GMT+03:00, Pavel Stehule <pavel.steh...@gmail.com> пишет: >2017-09-30 23:23 GMT+02:00 Pavel Stehule <pavel.steh...@gmail.com>: > >> Hi >> >> I have some strange slow queries based on usage "view" functions >> >> one function looks like this: >> >> CREATE OR REPLACE FUNCTION >ides_funcs.najdatsplt_cislo_exekuce(mid_najdatsplt >> bigint) >> RETURNS character varying >> LANGUAGE sql >> STABLE >> AS $function$ >> select CISLOEXEKUCE >> from najzalobpr MT, najvzallok A1, >> NAJZALOBST A2, NAJZALOBCE A3 where >> MT.ID_NAJVZALLOK= A1.ID_NAJVZALLOK AND >> A1.ID_NAJZALOBST=A2.ID_NAJZALOBST AND >> A2.ID_NAJZALOBCE= A3.ID_NAJZALOBCE AND >> MT.ID_NAJDATSPLT = mID_NAJDATSPLT LIMIT 1; >> $function$ cost 20 >> ; >> >> I know so using this kind of functions is not good idea - it is >customer >> old code generated from Oracle. I had idea about possible planner >issues. >> But this is a executor issue. >> >> when this function is evaluated as function, then execution needs >about 46 >> sec >> >> -> Nested Loop Left Join (cost=0.71..780360.31 rows=589657 >> width=2700) (actual time=47796.588..47796.588 rows=0 loops=1) >> -> Nested Loop (cost=0.29..492947.20 rows=589657 >width=2559) >> (actual time=47796.587..47796.587 rows=0 loops=1) >> -> Seq Scan on najdatsplt mt (cost=0.00..124359.24 >> rows=1106096 width=1013) (actual time=47796.587..47796.587 rows=0 >loops=1) >> Filter: >(najdatsplt_cislo_exekuce(id_najdatsplt) IS >> NOT NULL) >> Rows Removed by Filter: 1111654 >> >> When I use correlated subquery, then >> >> -> Nested Loop (cost=0.29..19876820.11 rows=589657 width=2559) >(actual >> time=3404.154..3404.154 rows=0 loops=1) >> -> Seq Scan on najdatsplt mt (cost=0.00..19508232.15 rows=1106096 >> width=1013) (actual time=3404.153..3404.153 rows=0 loops=1) >> Filter: ((SubPlan 11) IS NOT NULL) >> Rows Removed by Filter: 1111654 >> SubPlan 11 >> -> Limit (cost=1.10..17.49 rows=1 width=144) (actual >> time=0.002..0.002 rows=0 loops=1111654) >> -> Nested Loop (cost=1.10..17.49 rows=1 width=144) >(actual >> time=0.002..0.002 rows=0 loops=1111654) >> -> Nested Loop (cost=0.83..17.02 rows=1 >width=8) >> (actual time=0.002..0.002 rows=0 loops=1111654) >> -> Nested Loop (cost=0.56..16.61 rows=1 >> width=8) (actual time=0.002..0.002 rows=0 loops=1111654) >> >> The execution plan is +/- same - the bottleneck is in function >execution >> >> Tested with same result on 9.6, 10. >> >> Is known overhead of function execution? >> >> >profile of slow execution looks like > >+ 24,71% 24,40% 48235 postmaster [.] SearchCatCache >+ 14,25% 0,00% 0 postmaster [unknown] [.] >0000000000000000 >+ 9,76% 9,65% 19071 postmaster [.] >TupleDescInitEntry >+ 3,91% 3,86% 7625 postmaster [.] >ExecAssignScanProjectionInfoWithVarno >+ 3,56% 3,52% 6955 postmaster [.] AllocSetAlloc >+ 2,66% 2,63% 5193 postmaster [.] >FunctionCall2Coll >+ 2,65% 2,62% 5183 postmaster [.] >ResourceArrayRemove >+ 2,42% 2,39% 4719 postmaster [.] >ExecTypeFromTLInternal >+ 2,21% 2,19% 4321 postmaster [.] >DirectFunctionCall1Coll >+ 2,02% 2,00% 3961 postmaster [.] >heap_getsysattr >+ 1,85% 1,82% 3604 postmaster [.] >exprTypmod >+ 1,81% 1,79% 3540 postmaster [.] >ResourceArrayAdd >+ 1,68% 1,66% 3282 postmaster [.] >hash_uint32 >+ 1,65% 1,63% 3214 postmaster [.] >hash_search_with_hash_value >+ 1,64% 1,62% 3208 postmaster [.] >CatalogCacheComputeHashValue >+ 1,28% 1,26% 2498 postmaster [.] >MemoryContextAllocZeroAligned >+ 1,25% 1,24% 2446 postmaster [.] palloc0 > >Any ides why SearchCatCache is called too often? > > > >> Regards >> >> Pavel >>
Looks like you've already collected profile with call-graph. So you can tell us where it were called from. With regards, -- Sokolov Yura aka funny_falcon -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
