| From: | Mark Dilger <mark(dot)dilger(at)enterprisedb(dot)com> |
|---|---|
| To: | Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com> |
| Cc: | Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Use extended statistics to estimate (Var op Var) clauses |
| Date: | 2021-08-11 22:48:05 |
| Message-ID: | 73847924-FC53-4FEF-8F0D-C4A94BC8E72D@enterprisedb.com |
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| Lists: | pgsql-hackers |
> On Aug 11, 2021, at 3:45 PM, Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com> wrote:
>
> As I said in my last reply, I'm not sure it's particularly useful to look at overall results from data sets with independent columns. That's not what extended statistics are for, and people should not create them in those cases ...
We sent our last emails more or less simultaneously. I'm not ignoring your email; I just hadn't seen it yet when I sent mine.
> Maybe it'd be better to focus on cases with the largest difference in estimates, and investigate those more closely.
Yeah, I'm working on a correlated stats test as I write this. I'll get back to you when I have results.
—
Mark Dilger
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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