Re: RE : RE : BUG #3519: Postgres takes the wrong query plan resulting in performance issues

"Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:

> Gregory Stark <stark(at)enterprisedb(dot)com> writes:
>> The structure of your query is a whole series of left outer joins, the result
>> of which is then (inner) joined with one more table. The outer joins return a
>> whole lot of records but the inner join is only going to match a few of them.
>
> Hmmm ... actually I see 6 tables inside the join-tree and four more
> loose in the FROM-clause, ten relations altogether. Which means the OP
> is falling foul of from_collapse_limit, and it's not investigating every
> possible join order. Try setting from_collapse_limit to more than 10.

The three other loose ones are attached to a table inside outer joins though.
Doesn't that prevent any possibility of them being done earlier? But the first
one looks like it ought to be driving the join.

--
Gregory Stark
EnterpriseDB http://www.enterprisedb.com