| From: | Tomas Vondra <tomas(at)vondra(dot)me> |
|---|---|
| To: | Alena Rybakina <a(dot)rybakina(at)postgrespro(dot)ru>, Ilia Evdokimov <ilya(dot)evdokimov(at)tantorlabs(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Add support for (Var op Var) clause in extended MCV statistics |
| Date: | 2024-08-12 11:53:32 |
| Message-ID: | 73dd8031-b2a0-4ed8-b642-8afb196e6ce8@vondra.me |
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| Lists: | pgsql-hackers |
On 8/12/24 13:44, Alena Rybakina wrote:
> Hi! I think your work is important)
>
I agree, and I'm grateful someone picked up the original patch. I'll try
to help to keep it moving forward. If the thread gets stuck, feel free
to ping me to take a look.
> I started reviewing it and want to suggest some changes to better code:
> I think we should consider the case where the expression is not neither
> an OpExpr and VarOpVar expression.
>
Do you have some specific type of clauses in mind? Most of the extended
statistics only really handles this type of clauses, so I'm not sure
it's feasible to extend that - at least not in this patch.
> Have you tested this code with any benchmarks?
>
FWIW I think we need to test two things - that it (a) improves the
estimates and (b) does not have significant overhead.
regards
--
Tomas Vondra
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