Add GUCs for predicate lock promotion thresholds.

Defaults match the fixed behavior of prior releases, but now DBAs
have better options to tune serializable workloads.

It might be nice to be able to set this per relation, but that part
will need to wait for another release.

Author: Dagfinn Ilmari Mannsåker

1 files changed, 22 insertions, 0 deletions

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index a57b175b2d3..19d258d0336 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -2200,6 +2200,28 @@ static struct config_int ConfigureNamesInt[] =
 	},
 
 	{
+		{"max_pred_locks_per_relation", PGC_SIGHUP, LOCK_MANAGEMENT,
+			gettext_noop("Sets the maximum number of predicate-locked pages and tuples per relation."),
+			gettext_noop("If more than this total of pages and tuples in the same relation are locked "
+						 "by a connection, those locks are replaced by a relation level lock.")
+		},
+		&max_predicate_locks_per_relation,
+		-2, INT_MIN, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"max_pred_locks_per_page", PGC_SIGHUP, LOCK_MANAGEMENT,
+			gettext_noop("Sets the maximum number of predicate-locked tuples per page."),
+			gettext_noop("If more than this number of tuples on the same page are locked "
+						 "by a connection, those locks are replaced by a page level lock.")
+		},
+		&max_predicate_locks_per_page,
+		2, 0, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
 		{"authentication_timeout", PGC_SIGHUP, CONN_AUTH_SECURITY,
 			gettext_noop("Sets the maximum allowed time to complete client authentication."),
 			NULL,