pg19 – select * from depesz;

Add date and timestamp variants of random(min, max). This adds 3 new variants of the random() function: random(min date, max date) returns date random(min timestamp, max timestamp) returns timestamp random(min timestamptz, max timestamptz) returns timestamptz Each returns a random value x in the range min <= x <= max. Author: Damien Clochard <damien@dalibo.info> Reviewed-by: Greg Sabino Mullane <htamfids@gmail.com> Reviewed-by: Dean Rasheed <dean.a.rasheed@gmail.com> Reviewed-by: Vik Fearing <vik@postgresfriends.org> Reviewed-by: Chao Li <li.evan.chao@gmail.com> Discussion: https://postgr.es/m/f524d8cab5914613d9e624d9ce177d3d@dalibo.info

On 29th of July 2025, David Rowley committed patch:

Display Memoize planner estimates in EXPLAIN
 
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

Continue reading Waiting for PostgreSQL 19 – Display Memoize planner estimates in EXPLAIN

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Tag: pg19

Waiting for PostgreSQL 19 – Add date and timestamp variants of random(min, max).

Waiting for PostgreSQL 19 – Display Memoize planner estimates in EXPLAIN