Hi Ken, yes, I may do it, but I did not expect to come into profiling initially :-) I expected there is just something trivial within a plan that I just don't know.. :-) BTW, is there already an integrated profiled within a code? or do I need external tools?.. Rgds, -Dimitri On 5/6/09, Kenneth Marshall <ktm@xxxxxxxx> wrote: > On Wed, May 06, 2009 at 09:38:59AM +0200, Dimitri wrote: >> Hi, >> >> any idea if there is a more optimal execution plan possible for this >> query: >> >> select S.REF as stref, S.NAME as stnm, H.HORDER as hord, H.BEGIN_DATE as >> hbeg, >> H.END_DATE as hend, H.NOTE as hnote >> from HISTORY H, STAT S >> where S.REF = H.REF_STAT >> and H.REF_OBJECT = '0000000001' >> order by H.HORDER ; >> >> EXPLAIN ANALYZE output on 8.4: >> QUERY >> PLAN >> ------------------------------------------------------------------------------------------------------------------------------------------------ >> Sort (cost=4549.75..4555.76 rows=2404 width=176) (actual >> time=1.341..1.343 rows=20 loops=1) >> Sort Key: h.horder >> Sort Method: quicksort Memory: 30kB >> -> Hash Join (cost=33.50..4414.75 rows=2404 width=176) (actual >> time=1.200..1.232 rows=20 loops=1) >> Hash Cond: (h.ref_stat = s.ref) >> -> Index Scan using history_ref_idx on history h >> (cost=0.00..4348.20 rows=2404 width=135) (actual time=0.042..0.052 >> rows=20 loops=1) >> Index Cond: (ref_object = '0000000001'::bpchar) >> -> Hash (cost=21.00..21.00 rows=1000 width=45) (actual >> time=1.147..1.147 rows=1000 loops=1) >> -> Seq Scan on stat s (cost=0.00..21.00 rows=1000 >> width=45) (actual time=0.005..0.325 rows=1000 loops=1) >> Total runtime: 1.442 ms >> (10 rows) >> >> Table HISTORY contains 200M rows, only 20 needed >> Table STAT contains 1000 rows, only 20 needed to be joined to HISTORY >> values. >> >> Table definitions: >> """"""""""""""""""""""""""""""""""""""""""""""""""" >> create table STAT >> ( >> REF CHAR(3) not null, >> NAME CHAR(40) not null, >> NUMB INT not null >> ); >> >> create table HISTORY >> ( >> REF_OBJECT CHAR(10) not null, >> HORDER INT not null, >> REF_STAT CHAR(3) not null, >> BEGIN_DATE CHAR(12) not null, >> END_DATE CHAR(12) , >> NOTE CHAR(100) >> ); >> >> create unique index stat_ref_idx on STAT( ref ); >> create index history_ref_idx on HISTORY( ref_object, horder ); >> """"""""""""""""""""""""""""""""""""""""""""""""""" >> >> NOTE: The same query runs 2 times faster on MySQL. >> >> Any idea?.. >> >> Rgds, >> -Dimitri >> > Dimitri, > > Is there any chance of profiling the postgres backend to see > where the time is used? > > Just an idea, > Ken > -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
