Thanks Dave for correction, but I'm also curious where the time is wasted in this case?.. 0.84ms is displayed by "psql" once the result output is printed, and I got similar time within my client (using libpq) which is not printing any output.. Rgds, -Dimitri On 5/18/09, Dave Dutcher <dave@xxxxxxxxxxxx> wrote: > > What I don't understand is the part where you talking about disabling hash > joins: > >> * result: planner replaced hash join is replaced by merge join >> * execution time: 0.84ms ! >> * NOTE: curiously planner is expecting to execute this query in 0.29ms > - so it's supposed from its logic to be faster, so why this plan is not used > from the beginning???... >> >> Sort (cost=4562.83..4568.66 rows=2329 width=176) (actual > time=0.237..0.237 rows=20 loops=1) >> Sort Key: h.horder >> Sort Method: quicksort Memory: 30kB >> -> Merge Join (cost=4345.89..4432.58 rows=2329 width=176) > (actual time=0.065..0.216 rows=20 loops=1) >> Merge Cond: (s.ref = h.ref_stat) >> -> Index Scan using stat_ref_idx on stat s > (cost=0.00..49.25 rows=1000 width=45) (actual time=0.018..0.089 rows=193 > loops=1) >> -> Sort (cost=4345.89..4351.72 rows=2329 width=135) > (actual time=0.042..0.043 rows=20 loops=1) >> Sort Key: h.ref_stat >> Sort Method: quicksort Memory: 30kB >> -> Index Scan using history_ref_idx on history h > (cost=0.00..4215.64 rows=2329 width=135) (actual time=0.012..0.025 rows=20 > loops=1) >> Index Cond: (ref_object = '0000000001'::bpchar) >> Total runtime: 0.288 ms >> (12 rows) > > The explain analyze ran the query in 0.288 ms. That is the actual time it > took to run the query on the server. It is not an estimate of the time. > You measured 0.84 ms to run the query, which seems to imply either a problem > in one of the timing methods or that 66% of your query execution time is > sending the results to the client. I'm curious how you did you execution > time measurements. > > Dave > > -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
