Re: wrong count estimation in query plan

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ÔÚ 2014/10/30 22:25, Tom Lane дµÀ:
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.


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