Re: wrong count estimation in query plan

在 2014/10/30 22:25, Tom Lane 写道:
> If ANALYZE doesn't scan the entire table then it updates the rowcount
> estimate using a moving-average approach, rather than assuming that
> the blocks it did look at are necessarily completely representative.
> That causes the estimate to converge over multiple passes. Since it
> took so many cycles to get close to reality, we can conclude that the
> table is several times larger than the number of blocks ANALYZE is
> willing to sample ... which, for a table with only 1000 rows in it,
> says you've got a bad table-bloat problem. VACUUM FULL or CLUSTER
> might be indicated. regards, tom lane
Got it. A vacuum solved the problem. Thanks.