| From: | Jeff Amiel <becauseimjeff(at)yahoo(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | pgsql-general(at)postgresql(dot)org |
| Subject: | Re: Oddball data distribution giving me planner headaches |
| Date: | 2011-12-02 23:11:42 |
| Message-ID: | 1322867502.54335.YahooMailClassic@web65506.mail.ac4.yahoo.com |
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| Lists: | pgsql-general |
--- On Fri, 12/2/11, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> The only real fix for that will require cross-column
> statistics, which
> we don't have yet --- without such, there's no way for the
> planner to
> know that distributors have an atypical number of child
> customers.
The only caveat that I can think of here is that each of the customer_id's in the subselect ARE in the MCV list for the parent_customer column for that customer_rel table. If I had listed SPECIFIC customer ids in the subselect, I would get spot-on row estimates. Is there anything there that gives me any hope?
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