Document how to create advisory lock "bigint" values in SQL.

David E. Wheeler

diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index b100a426e484d9f499a086bba5de074132636529..bf568f181137a940081ca171b3a9169351b95ff6 100644 (file)
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -7412,7 +7412,10 @@
    A bigint key is displayed with its
    high-order half in the classid column, its low-order half
    in the objid column, and objsubid equal
-   to 1.  Integer keys are displayed with the first key in the
+   to 1. The original bigint value can be reassembled with the
+   expression (classid::int::bit(64) << 32 |
+   objid::int::bit(64))::bigint. Integer keys are displayed with the
+   first key in the
    classid column, the second key in the objid
    column, and objsubid equal to 2.  The actual meaning of
    the keys is up to the user.  Advisory locks are local to each database,