2017-10-01 12:45 GMT+02:00 Sokolov Yura <funny.fal...@postgrespro.ru>:
> 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. > There was zero info. I'll try to install this database on my notebook, and I'll see Pavel > > With regards, > -- > Sokolov Yura aka funny_falcon >
