Add note that TRUNCATE uses an access exclusive lock. This apparently

surprised/confused some users.

diff --git a/doc/src/sgml/ref/truncate.sgml b/doc/src/sgml/ref/truncate.sgml
index cae4af45930bdadf75d8762dbf3d231fdb5ee82a..d05bbec8618262f936f70a195712abe4ecc23b1b 100644 (file)
--- a/doc/src/sgml/ref/truncate.sgml
+++ b/doc/src/sgml/ref/truncate.sgml
@@ -102,6 +102,13 @@ TRUNCATE [ TABLE ] <replaceable class="PARAMETER">name</replaceable> [, ... ]
    to truncate it.
   </para>
 
+  <para>
+   <command>TRUNCATE</> acquires an access exclusive lock on the
+   tables in operates on, which blocks all other concurrent operations
+   on the table.  If concurrent access to a table is required, then
+   the <command>DELETE</> command should be used instead.
+  </para>
+
   <para>
    <command>TRUNCATE</> cannot be used on a table that has foreign-key
    references from other tables, unless all such tables are also truncated