diff --git a/doc/src/sgml/ref/select.sgml b/doc/src/sgml/ref/select.sgml
index 5046326e54c..c528010723b 100644
--- a/doc/src/sgml/ref/select.sgml
+++ b/doc/src/sgml/ref/select.sgml
@@ -1,5 +1,5 @@
@@ -818,6 +818,16 @@ FOR UPDATE [ OF table_name [, ...]
rows; for example it can't be used with aggregation.
+
+ It is possible for a SELECT> command using both
+ LIMIT and FOR UPDATE
+ clauses to return fewer rows than specified by LIMIT.
+ This is because LIMIT> selects a number of rows,
+ but might then block requesting a FOR UPDATE lock.
+ Once the SELECT> unblocks, the query qualification might not
+ be met and the row not be returned by SELECT>.
+
+
FOR UPDATE may appear before
LIMIT for compatibility with