| From: | Ilia Evdokimov <ilya(dot)evdokimov(at)tantorlabs(dot)com> |
|---|---|
| To: | Chengpeng Yan <chengpeng_yan(at)Outlook(dot)com> |
| Cc: | Tatsuya Kawata <kawatatatsuya0913(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, John Naylor <johncnaylorls(at)gmail(dot)com> |
| Subject: | Re: [PATCH] ANALYZE: hash-accelerate MCV tracking for equality-only types |
| Date: | 2026-02-26 11:46:32 |
| Message-ID: | 4f51168a-3a3e-4bae-b2e9-ba7bb05c06f7@tantorlabs.com |
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| Lists: | pgsql-hackers |
Have you benchmarked this change except in first message in this thread?
While reviewing the patch more closely, I noticed
that compute_distinct_stats() is only used for types where we have =, !=
but not <. In practice, most common scalar types go through
compute_scalar_stats() instead.
That makes me wonder how often this optimization would actually trigger
in real workloads. Since compute_scalar_stats() is the more common path,
there's chance that the hash-table based improvement in
compute_distinct_stats() may not provide a noticeable overall benefit.
--
Best regards,
Ilia Evdokimov,
Tantor Labs LLC,
https://tantorlabs.com/
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