pgsql-performance@postgresql.org
Subject: Re: [PERFORM] same query different execution plan (hash join vs.
semi-hash join)
"Huang, Suya" writes:
> Thank you Tom. But the time spent on scanning table test1 is less than 1
> second (91.738 compares to 87.869), so I guess this shouldn
"Huang, Suya" writes:
> Thank you Tom. But the time spent on scanning table test1 is less than 1
> second (91.738 compares to 87.869), so I guess this shouldn't be the issue?
No, the point is that the bad rowcount estimate (and, possibly, lack of
stats about join column contents) causes the plan
mance@postgresql.org
Subject: Re: [PERFORM] same query different execution plan (hash join vs.
semi-hash join)
"Huang, Suya" writes:
> I've got a query as below, it runs several times with different execution
> plan and totally different execution time. The one using hash-j
"Huang, Suya" writes:
> I've got a query as below, it runs several times with different execution
> plan and totally different execution time. The one using hash-join is slow
> and the one using semi-hash join is very fast. However, I have no control
> over the optimizer behavior of PostgreSQL
