Fix failure with lock mode used for custom relation options

In-core relation options can use a custom lock mode since 47167b7, that
has lowered the lock available for some autovacuum parameters.  However
it forgot to consider custom relation options.  This causes failures
with ALTER TABLE SET when changing a custom relation option, as its lock
is not defined.  The existing APIs to define a custom reloption does not
allow to define a custom lock mode, so enforce its initialization to
AccessExclusiveMode which should be safe enough in all cases.  An
upcoming patch will extend the existing APIs to allow a custom lock mode
to be defined.

The problem can be reproduced with bloom indexes, so add a test there.

Reported-by: Nikolay Sharplov
Analyzed-by: Thomas Munro, Michael Paquier
Author: Michael Paquier
Reviewed-by: Kuntal Ghosh
Discussion: https://postgr.es/m/20190920013831.GD1844@paquier.xyz
Backpatch-through: 9.6

diff --git a/contrib/bloom/expected/bloom.out b/contrib/bloom/expected/bloom.out
index 5ab9e34f823db5fb745e4fa0effab7eed2c6f7c4..dae12a7d3e7e04763192adcb61ab0932133c8a57 100644 (file)
--- a/contrib/bloom/expected/bloom.out
+++ b/contrib/bloom/expected/bloom.out
@@ -5,6 +5,7 @@ CREATE TABLE tst (
 );
 INSERT INTO tst SELECT i%10, substr(md5(i::text), 1, 1) FROM generate_series(1,2000) i;
 CREATE INDEX bloomidx ON tst USING bloom (i, t) WITH (col1 = 3);
+ALTER INDEX bloomidx SET (length=80);
 SET enable_seqscan=on;
 SET enable_bitmapscan=off;
 SET enable_indexscan=off;

diff --git a/contrib/bloom/sql/bloom.sql b/contrib/bloom/sql/bloom.sql
index 32755f2b1a53d82eb59e4698ef0f429488a025d8..4733e1e7050e5b864f53554ae2d536659bdecf69 100644 (file)
--- a/contrib/bloom/sql/bloom.sql
+++ b/contrib/bloom/sql/bloom.sql
@@ -7,6 +7,7 @@ CREATE TABLE tst (
 
 INSERT INTO tst SELECT i%10, substr(md5(i::text), 1, 1) FROM generate_series(1,2000) i;
 CREATE INDEX bloomidx ON tst USING bloom (i, t) WITH (col1 = 3);
+ALTER INDEX bloomidx SET (length=80);
 
 SET enable_seqscan=on;
 SET enable_bitmapscan=off;

diff --git a/src/backend/access/common/reloptions.c b/src/backend/access/common/reloptions.c
index 577302149931b53087c12333266ae941d26e1937..2e1dcb932377f5b41fceb911706340c292441641 100644 (file)
--- a/src/backend/access/common/reloptions.c
+++ b/src/backend/access/common/reloptions.c
@@ -659,6 +659,13 @@ allocate_reloption(bits32 kinds, int type, const char *name, const char *desc)
        newoption->namelen = strlen(name);
        newoption->type = type;
 
+       /*
+        * Set the default lock mode for this option.  There is no actual way
+        * for a module to enforce it when declaring a custom relation option,
+        * so just use the highest level, which is safe for all cases.
+        */
+       newoption->lockmode = AccessExclusiveLock;
+
        MemoryContextSwitchTo(oldcxt);
 
        return newoption;