Lock table in ShareUpdateExclusive when importing index stats.

Follow locking behavior of ANALYZE when importing statistics. In
particular, when importing index statistics, the table must be locked
in ShareUpdateExclusive mode. Fixes bug reportd by Jian He.

ANALYZE doesn't update statistics on partitioned indexes, and the
locking requirements are slightly different for in-place updates on
partitioned indexes versus normal indexes. To be conservative, lock
both the partitioned table and the partitioned index in
ShareUpdateExclusive mode when importing stats for a partitioned
index.

Author: Corey Huinker
Reported-by: Jian He
Reviewed-by: Michael Paquier
Discussion: https://www.postgresql.org/message-id/CACJufxGreTY7qsCV8%2BBkuv0p5SXGTScgh%3DD%2BDq6%3D%2B_%3DXTp7FWg%40mail.gmail.com

2 files changed, 171 insertions, 0 deletions

diff --git a/src/test/regress/expected/stats_import.out b/src/test/regress/expected/stats_import.out
index fb50da1cd83..0e8491131e3 100644
--- a/src/test/regress/expected/stats_import.out
+++ b/src/test/regress/expected/stats_import.out
@@ -85,6 +85,44 @@ WHERE oid = 'stats_import.test'::regclass;
        17 |       400 |             4
 (1 row)
 
+CREATE INDEX test_i ON stats_import.test(id);
+BEGIN;
+-- regular indexes have special case locking rules
+SELECT
+    pg_catalog.pg_set_relation_stats(
+        relation => 'stats_import.test_i'::regclass,
+        relpages => 18::integer);
+ pg_set_relation_stats 
+-----------------------
+ 
+(1 row)
+
+SELECT mode FROM pg_locks
+WHERE relation = 'stats_import.test'::regclass AND
+      pid = pg_backend_pid() AND granted;
+           mode           
+--------------------------
+ ShareUpdateExclusiveLock
+(1 row)
+
+SELECT mode FROM pg_locks
+WHERE relation = 'stats_import.test_i'::regclass AND
+      pid = pg_backend_pid() AND granted;
+      mode       
+-----------------
+ AccessShareLock
+(1 row)
+
+COMMIT;
+SELECT
+    pg_catalog.pg_restore_relation_stats(
+        'relation', 'stats_import.test_i'::regclass,
+        'relpages', 19::integer );
+ pg_restore_relation_stats 
+---------------------------
+ t
+(1 row)
+
 -- positional arguments
 SELECT
     pg_catalog.pg_set_relation_stats(
@@ -182,6 +220,7 @@ CREATE TABLE stats_import.part_child_1
   PARTITION OF stats_import.part_parent
   FOR VALUES FROM (0) TO (10)
   WITH (autovacuum_enabled = false);
+CREATE INDEX part_parent_i ON stats_import.part_parent(i);
 ANALYZE stats_import.part_parent;
 SELECT relpages
 FROM pg_class
@@ -195,6 +234,15 @@ WHERE oid = 'stats_import.part_parent'::regclass;
 -- positive value is still allowed
 SELECT
     pg_catalog.pg_set_relation_stats(
+        relation => 'stats_import.part_parent_i'::regclass,
+        relpages => 2::integer);
+ pg_set_relation_stats 
+-----------------------
+ 
+(1 row)
+
+SELECT
+    pg_catalog.pg_set_relation_stats(
         relation => 'stats_import.part_parent'::regclass,
         relpages => 2::integer);
  pg_set_relation_stats 
@@ -202,6 +250,48 @@ SELECT
  
 (1 row)
 
+--
+-- Partitioned indexes aren't analyzed but it is possible to set
+-- stats. The locking rules are different from normal indexes due to
+-- the rules for in-place updates: both the partitioned table and the
+-- partitioned index are locked in ShareUpdateExclusive mode.
+--
+BEGIN;
+SELECT
+    pg_catalog.pg_set_relation_stats(
+        relation => 'stats_import.part_parent_i'::regclass,
+        relpages => 2::integer);
+ pg_set_relation_stats 
+-----------------------
+ 
+(1 row)
+
+SELECT mode FROM pg_locks
+WHERE relation = 'stats_import.part_parent'::regclass AND
+      pid = pg_backend_pid() AND granted;
+           mode           
+--------------------------
+ ShareUpdateExclusiveLock
+(1 row)
+
+SELECT mode FROM pg_locks
+WHERE relation = 'stats_import.part_parent_i'::regclass AND
+      pid = pg_backend_pid() AND granted;
+           mode           
+--------------------------
+ ShareUpdateExclusiveLock
+(1 row)
+
+COMMIT;
+SELECT
+    pg_catalog.pg_restore_relation_stats(
+        'relation', 'stats_import.part_parent_i'::regclass,
+        'relpages', 2::integer);
+ pg_restore_relation_stats 
+---------------------------
+ t
+(1 row)
+
 -- nothing stops us from setting it to -1
 SELECT
     pg_catalog.pg_set_relation_stats(
@@ -1414,6 +1504,19 @@ SELECT 3, 'tre', (3, 3.3, 'TRE', '2003-03-03', NULL)::stats_import.complex_type,
 UNION ALL
 SELECT 4, 'four', NULL, int4range(0,100), NULL;
 CREATE INDEX is_odd ON stats_import.test(((comp).a % 2 = 1));
+-- restoring stats on index
+SELECT * FROM pg_catalog.pg_restore_relation_stats(
+    'relation', 'stats_import.is_odd'::regclass,
+    'version', '180000'::integer,
+    'relpages', '11'::integer,
+    'reltuples', '10000'::real,
+    'relallvisible', '0'::integer
+);
+ pg_restore_relation_stats 
+---------------------------
+ t
+(1 row)
+
 -- Generate statistics on table with data
 ANALYZE stats_import.test;
 CREATE TABLE stats_import.test_clone ( LIKE stats_import.test )
diff --git a/src/test/regress/sql/stats_import.sql b/src/test/regress/sql/stats_import.sql
index d3058bf8f6b..5e24c779d80 100644
--- a/src/test/regress/sql/stats_import.sql
+++ b/src/test/regress/sql/stats_import.sql
@@ -64,6 +64,30 @@ SELECT relpages, reltuples, relallvisible
 FROM pg_class
 WHERE oid = 'stats_import.test'::regclass;
 
+CREATE INDEX test_i ON stats_import.test(id);
+
+BEGIN;
+-- regular indexes have special case locking rules
+SELECT
+    pg_catalog.pg_set_relation_stats(
+        relation => 'stats_import.test_i'::regclass,
+        relpages => 18::integer);
+
+SELECT mode FROM pg_locks
+WHERE relation = 'stats_import.test'::regclass AND
+      pid = pg_backend_pid() AND granted;
+
+SELECT mode FROM pg_locks
+WHERE relation = 'stats_import.test_i'::regclass AND
+      pid = pg_backend_pid() AND granted;
+
+COMMIT;
+
+SELECT
+    pg_catalog.pg_restore_relation_stats(
+        'relation', 'stats_import.test_i'::regclass,
+        'relpages', 19::integer );
+
 -- positional arguments
 SELECT
     pg_catalog.pg_set_relation_stats(
@@ -127,6 +151,8 @@ CREATE TABLE stats_import.part_child_1
   FOR VALUES FROM (0) TO (10)
   WITH (autovacuum_enabled = false);
 
+CREATE INDEX part_parent_i ON stats_import.part_parent(i);
+
 ANALYZE stats_import.part_parent;
 
 SELECT relpages
@@ -137,9 +163,42 @@ WHERE oid = 'stats_import.part_parent'::regclass;
 -- positive value is still allowed
 SELECT
     pg_catalog.pg_set_relation_stats(
+        relation => 'stats_import.part_parent_i'::regclass,
+        relpages => 2::integer);
+
+SELECT
+    pg_catalog.pg_set_relation_stats(
         relation => 'stats_import.part_parent'::regclass,
         relpages => 2::integer);
 
+--
+-- Partitioned indexes aren't analyzed but it is possible to set
+-- stats. The locking rules are different from normal indexes due to
+-- the rules for in-place updates: both the partitioned table and the
+-- partitioned index are locked in ShareUpdateExclusive mode.
+--
+BEGIN;
+
+SELECT
+    pg_catalog.pg_set_relation_stats(
+        relation => 'stats_import.part_parent_i'::regclass,
+        relpages => 2::integer);
+
+SELECT mode FROM pg_locks
+WHERE relation = 'stats_import.part_parent'::regclass AND
+      pid = pg_backend_pid() AND granted;
+
+SELECT mode FROM pg_locks
+WHERE relation = 'stats_import.part_parent_i'::regclass AND
+      pid = pg_backend_pid() AND granted;
+
+COMMIT;
+
+SELECT
+    pg_catalog.pg_restore_relation_stats(
+        'relation', 'stats_import.part_parent_i'::regclass,
+        'relpages', 2::integer);
+
 -- nothing stops us from setting it to -1
 SELECT
     pg_catalog.pg_set_relation_stats(
@@ -1062,6 +1121,15 @@ SELECT 4, 'four', NULL, int4range(0,100), NULL;
 
 CREATE INDEX is_odd ON stats_import.test(((comp).a % 2 = 1));
 
+-- restoring stats on index
+SELECT * FROM pg_catalog.pg_restore_relation_stats(
+    'relation', 'stats_import.is_odd'::regclass,
+    'version', '180000'::integer,
+    'relpages', '11'::integer,
+    'reltuples', '10000'::real,
+    'relallvisible', '0'::integer
+);
+
 -- Generate statistics on table with data
 ANALYZE stats_import.test;