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