| From: | Rod Taylor <rbt(at)rbt(dot)ca> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | ow <oneway_111(at)yahoo(dot)com>, pgsql-sql(at)postgresql(dot)org |
| Subject: | Re: 7.4 - FK constraint performance |
| Date: | 2004-02-13 13:57:50 |
| Message-ID: | 1076680669.10896.17.camel@jester |
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| Lists: | pgsql-hackers pgsql-sql |
On Thu, 2004-02-12 at 23:25, Tom Lane wrote:
> Rod Taylor <rbt(at)rbt(dot)ca> writes:
> > Statistics say there are 10 values. Statistics list the 10 most common
> > values (all of them). Given this, would it not be reasonable to assume
> > that 239 is a recent addition (if there at all) to the table and not
> > very common?
>
> We don't know that it's 239 when we make the plan. In order to know
> that, we'd have to abandon caching of RI check query plans and re-plan
> for each row. That strikes me as inevitably a losing proposition.
Right, sorry, I forgot this was out of a fk trigger.
--
Rod Taylor <rbt [at] rbt [dot] ca>
Build A Brighter Lamp :: Linux Apache {middleware} PostgreSQL
PGP Key: http://www.rbt.ca/rbtpub.asc
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