From: Tom Lane <tgl@sss.pgh.pa.us>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Improve the implementation of information_schema._pg_expandarray
Date: Wed, 27 Dec 2023 20:55:54 +0000
Message-ID: <E1rIawT-00CCqw-M2@gemulon.postgresql.org> (raw)
Improve the implementation of information_schema._pg_expandarray().
This function was originally coded with a handmade expansion
of the array subscripts. We can do it a little faster and far
more legibly today, by using unnest() WITH ORDINALITY.
While at it, let's apply the rowcount estimation support that exists
for the underlying unnest() function: reduce the default ROWS estimate
to 100 and attach array_unnest_support. I'm not sure that
array_unnest_support can do anything useful today with the call sites
that exist in information_schema, but it can't hurt, and the existing
default rowcount of 1000 is surely much too high for any of these
cases.
The psql.sql regression script is using _pg_expandarray() as a
test case for \sf+. While we could keep doing so, the new one-line
function body makes a poor test case for \sf+ row-numbering, so
switch it to print another information_schema function.
Discussion: https://postgr.es/m/1424303.1703355485@sss.pgh.pa.us
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/58054de2d0847c09ef091956f72ae5e9fb9a176e
Modified Files
--------------
src/backend/catalog/information_schema.sql | 7 ++----
src/backend/utils/adt/arrayfuncs.c | 3 +++
src/include/catalog/catversion.h | 2 +-
src/test/regress/expected/psql.out | 40 ++++++++++++++++--------------
src/test/regress/sql/psql.sql | 4 +--
5 files changed, 30 insertions(+), 26 deletions(-)
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To: pgsql-committers@postgresql.org
Cc: tgl@sss.pgh.pa.us, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Improve the implementation of information_schema._pg_expandarray
In-Reply-To: <E1rIawT-00CCqw-M2@gemulon.postgresql.org>
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