From 58054de2d0847c09ef091956f72ae5e9fb9a176e Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Wed, 27 Dec 2023 15:55:46 -0500 Subject: [PATCH] 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 --- 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(-) diff --git a/src/backend/catalog/information_schema.sql b/src/backend/catalog/information_schema.sql index 10b34c3c5b..893f73ecb5 100644 --- a/src/backend/catalog/information_schema.sql +++ b/src/backend/catalog/information_schema.sql @@ -43,11 +43,8 @@ SET search_path TO information_schema; CREATE FUNCTION _pg_expandarray(IN anyarray, OUT x anyelement, OUT n int) RETURNS SETOF RECORD LANGUAGE sql STRICT IMMUTABLE PARALLEL SAFE - AS 'select $1[s], - s operator(pg_catalog.-) pg_catalog.array_lower($1,1) operator(pg_catalog.+) 1 - from pg_catalog.generate_series(pg_catalog.array_lower($1,1), - pg_catalog.array_upper($1,1), - 1) as g(s)'; + ROWS 100 SUPPORT pg_catalog.array_unnest_support + AS 'SELECT * FROM pg_catalog.unnest($1) WITH ORDINALITY'; /* Given an index's OID and an underlying-table column number, return the * column's position in the index (NULL if not there) */ diff --git a/src/backend/utils/adt/arrayfuncs.c b/src/backend/utils/adt/arrayfuncs.c index 631012a0f2..e783a24519 100644 --- a/src/backend/utils/adt/arrayfuncs.c +++ b/src/backend/utils/adt/arrayfuncs.c @@ -6317,6 +6317,9 @@ array_unnest(PG_FUNCTION_ARGS) /* * Planner support function for array_unnest(anyarray) + * + * Note: this is now also used for information_schema._pg_expandarray(), + * which is simply a wrapper around array_unnest(). */ Datum array_unnest_support(PG_FUNCTION_ARGS) diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h index 2fd601add0..dad0056f79 100644 --- a/src/include/catalog/catversion.h +++ b/src/include/catalog/catversion.h @@ -57,6 +57,6 @@ */ /* yyyymmddN */ -#define CATALOG_VERSION_NO 202312251 +#define CATALOG_VERSION_NO 202312271 #endif diff --git a/src/test/regress/expected/psql.out b/src/test/regress/expected/psql.out index 13e4f6db7b..5d61e4c7bb 100644 --- a/src/test/regress/expected/psql.out +++ b/src/test/regress/expected/psql.out @@ -5293,26 +5293,30 @@ comment on function psql_df_plpgsql () is 'some comment'; rollback; drop role regress_psql_user; -- check \sf -\sf information_schema._pg_expandarray -CREATE OR REPLACE FUNCTION information_schema._pg_expandarray(anyarray, OUT x anyelement, OUT n integer) - RETURNS SETOF record +\sf information_schema._pg_index_position +CREATE OR REPLACE FUNCTION information_schema._pg_index_position(oid, smallint) + RETURNS integer LANGUAGE sql - IMMUTABLE PARALLEL SAFE STRICT -AS $function$select $1[s], - s operator(pg_catalog.-) pg_catalog.array_lower($1,1) operator(pg_catalog.+) 1 - from pg_catalog.generate_series(pg_catalog.array_lower($1,1), - pg_catalog.array_upper($1,1), - 1) as g(s)$function$ -\sf+ information_schema._pg_expandarray - CREATE OR REPLACE FUNCTION information_schema._pg_expandarray(anyarray, OUT x anyelement, OUT n integer) - RETURNS SETOF record + STABLE STRICT +BEGIN ATOMIC + SELECT (ss.a).n AS n + FROM ( SELECT information_schema._pg_expandarray(pg_index.indkey) AS a + FROM pg_index + WHERE (pg_index.indexrelid = $1)) ss + WHERE ((ss.a).x = $2); +END +\sf+ information_schema._pg_index_position + CREATE OR REPLACE FUNCTION information_schema._pg_index_position(oid, smallint) + RETURNS integer LANGUAGE sql - IMMUTABLE PARALLEL SAFE STRICT -1 AS $function$select $1[s], -2 s operator(pg_catalog.-) pg_catalog.array_lower($1,1) operator(pg_catalog.+) 1 -3 from pg_catalog.generate_series(pg_catalog.array_lower($1,1), -4 pg_catalog.array_upper($1,1), -5 1) as g(s)$function$ + STABLE STRICT +1 BEGIN ATOMIC +2 SELECT (ss.a).n AS n +3 FROM ( SELECT information_schema._pg_expandarray(pg_index.indkey) AS a +4 FROM pg_index +5 WHERE (pg_index.indexrelid = $1)) ss +6 WHERE ((ss.a).x = $2); +7 END \sf+ interval_pl_time CREATE OR REPLACE FUNCTION pg_catalog.interval_pl_time(interval, time without time zone) RETURNS time without time zone diff --git a/src/test/regress/sql/psql.sql b/src/test/regress/sql/psql.sql index 695c72d866..f199d624d3 100644 --- a/src/test/regress/sql/psql.sql +++ b/src/test/regress/sql/psql.sql @@ -1312,8 +1312,8 @@ rollback; drop role regress_psql_user; -- check \sf -\sf information_schema._pg_expandarray -\sf+ information_schema._pg_expandarray +\sf information_schema._pg_index_position +\sf+ information_schema._pg_index_position \sf+ interval_pl_time \sf ts_debug(text) \sf+ ts_debug(text)