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Diffstat (limited to 'doc/src/sgml/ref/create_sequence.sgml')
| -rw-r--r-- | doc/src/sgml/ref/create_sequence.sgml | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/doc/src/sgml/ref/create_sequence.sgml b/doc/src/sgml/ref/create_sequence.sgml index 9e364ff2409..c9591462eed 100644 --- a/doc/src/sgml/ref/create_sequence.sgml +++ b/doc/src/sgml/ref/create_sequence.sgml @@ -240,6 +240,16 @@ SELECT * FROM <replaceable>name</replaceable>; </para> <para> + Because <function>nextval</> and <function>setval</> calls are never + rolled back, sequence objects cannot be used if <quote>gapless</> + assignment of sequence numbers is needed. It is possible to build + gapless assignment by using exclusive locking of a table containing a + counter; but this solution is much more expensive than sequence + objects, especially if many transactions need sequence numbers + concurrently. + </para> + + <para> Unexpected results might be obtained if a <replaceable class="parameter">cache</replaceable> setting greater than one is used for a sequence object that will be used concurrently by |