Mark pageinspect's disk-accessing functions as parallel restricted.

tglsfdc · tglsfdc · commit aeaaf520f409 · 2022-11-21T15:37:10.000-05:00
These functions have been marked parallel safe, but the buildfarm's response to commit e2933a6 exposed the flaw in that thinking: if you try to use them on a temporary table, and they run inside a parallel worker, they'll fail with "cannot access temporary tables during a parallel operation". Fix that by marking them parallel restricted instead. Maybe someday we'll have a better answer and can reverse this decision. Back-patch to v15. To go back further, we'd have to devise variant versions of pre-1.10 pageinspect versions. Given the lack of field complaints, it doesn't seem worth the trouble. We'll just deem this case unsupported pre-v15. (If anyone does complain, it might be good enough to update the markings manually in their DBs.) Discussion: https://postgr.es/m/E1ox94a-000EHu-VH@gemulon.postgresql.org
diff --git a/contrib/pageinspect/Makefile b/contrib/pageinspect/Makefile
@@ -13,7 +13,8 @@ OBJS = \
 	rawpage.o
 
 EXTENSION = pageinspect
-DATA =  pageinspect--1.9--1.10.sql pageinspect--1.8--1.9.sql \
+DATA =  pageinspect--1.10--1.11.sql \
+	pageinspect--1.9--1.10.sql pageinspect--1.8--1.9.sql \
 	pageinspect--1.7--1.8.sql pageinspect--1.6--1.7.sql \
 	pageinspect--1.5.sql pageinspect--1.5--1.6.sql \
 	pageinspect--1.4--1.5.sql pageinspect--1.3--1.4.sql \
diff --git a/contrib/pageinspect/meson.build b/contrib/pageinspect/meson.build
@@ -33,6 +33,7 @@ install_data(
   'pageinspect--1.7--1.8.sql',
   'pageinspect--1.8--1.9.sql',
   'pageinspect--1.9--1.10.sql',
+  'pageinspect--1.10--1.11.sql',
   'pageinspect.control',
   kwargs: contrib_data_args,
 )
diff --git a/contrib/pageinspect/pageinspect--1.10--1.11.sql b/contrib/pageinspect/pageinspect--1.10--1.11.sql
@@ -0,0 +1,28 @@
+/* contrib/pageinspect/pageinspect--1.10--1.11.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pageinspect UPDATE TO '1.11'" to load this file. \quit
+
+--
+-- Functions that fetch relation pages must be PARALLEL RESTRICTED,
+-- not PARALLEL SAFE, otherwise they will fail when run on a
+-- temporary table in a parallel worker process.
+--
+
+ALTER FUNCTION get_raw_page(text, int8) PARALLEL RESTRICTED;
+ALTER FUNCTION get_raw_page(text, text, int8) PARALLEL RESTRICTED;
+-- tuple_data_split must be restricted because it may fetch TOAST data.
+ALTER FUNCTION tuple_data_split(oid, bytea, integer, integer, text) PARALLEL RESTRICTED;
+ALTER FUNCTION tuple_data_split(oid, bytea, integer, integer, text, bool) PARALLEL RESTRICTED;
+-- heap_page_item_attrs must be restricted because it calls tuple_data_split.
+ALTER FUNCTION heap_page_item_attrs(bytea, regclass, bool) PARALLEL RESTRICTED;
+ALTER FUNCTION heap_page_item_attrs(bytea, regclass) PARALLEL RESTRICTED;
+ALTER FUNCTION bt_metap(text) PARALLEL RESTRICTED;
+ALTER FUNCTION bt_page_stats(text, int8) PARALLEL RESTRICTED;
+ALTER FUNCTION bt_page_items(text, int8) PARALLEL RESTRICTED;
+ALTER FUNCTION hash_bitmap_info(regclass, int8) PARALLEL RESTRICTED;
+-- brin_page_items might be parallel safe, because it seems to touch
+-- only index metadata, but I don't think there's a point in risking it.
+-- Likewise for gist_page_items.
+ALTER FUNCTION brin_page_items(bytea, regclass) PARALLEL RESTRICTED;
+ALTER FUNCTION gist_page_items(bytea, regclass) PARALLEL RESTRICTED;
diff --git a/contrib/pageinspect/pageinspect.control b/contrib/pageinspect/pageinspect.control
@@ -1,5 +1,5 @@
 # pageinspect extension
 comment = 'inspect the contents of database pages at a low level'
-default_version = '1.10'
+default_version = '1.11'
 module_pathname = '$libdir/pageinspect'
 relocatable = true

Original file line number	Diff line number	Diff line change
`@@ -33,6 +33,7 @@ install_data(`
`33`	`33`	`'pageinspect--1.7--1.8.sql',`
`34`	`34`	`'pageinspect--1.8--1.9.sql',`
`35`	`35`	`'pageinspect--1.9--1.10.sql',`
	`36`	`+ 'pageinspect--1.10--1.11.sql',`
`36`	`37`	`'pageinspect.control',`
`37`	`38`	`kwargs: contrib_data_args,`
`38`	`39`	`)`