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MDB-32132: fix grantor selection for mdb_superuser#4

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reshke merged 1 commit intoMDB_15_10_aqofrom
hufew
Jan 17, 2025
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MDB-32132: fix grantor selection for mdb_superuser#4
reshke merged 1 commit intoMDB_15_10_aqofrom
hufew

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@reshke reshke commented Jan 16, 2025

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@reshke reshke merged commit 46f3258 into MDB_15_10_aqo Jan 17, 2025
@reshke reshke deleted the hufew branch January 30, 2025 15:59
reshke pushed a commit that referenced this pull request Nov 25, 2025
There've been a few complaints that it can be overly difficult to figure
out why the planner picked a Memoize plan.  To help address that, here we
adjust the EXPLAIN output to display the following additional details:

1) The estimated number of cache entries that can be stored at once
2) The estimated number of unique lookup keys that we expect to see
3) The number of lookups we expect
4) The estimated hit ratio

Technically #4 can be calculated using #1, #2 and #3, but it's not a
particularly obvious calculation, so we opt to display it explicitly.
The original patch by Lukas Fittl only displayed the hit ratio, but
there was a fear that might lead to more questions about how that was
calculated.  The idea with displaying all 4 is to be transparent which
may allow queries to be tuned more easily.  For example, if #2 isn't
correct then maybe extended statistics or a manual n_distinct estimate can
be used to help fix poor plan choices.

Author: Ilia Evdokimov <ilya.evdokimov@tantorlabs.com>
Author: Lukas Fittl <lukas@fittl.com>
Reviewed-by: David Rowley <dgrowleyml@gmail.com>
Reviewed-by: Andrei Lepikhov <lepihov@gmail.com>
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Discussion: https://postgr.es/m/CAP53Pky29GWAVVk3oBgKBDqhND0BRBN6yTPeguV_qSivFL5N_g%40mail.gmail.com
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