Clarify description of SET CONSTRAINTS. Point out that it is still

missing the ability to schema-qualify constraint names.

diff --git a/doc/src/sgml/ref/set_constraints.sgml b/doc/src/sgml/ref/set_constraints.sgml
index 47aa46da6ff13b1ed215e3623219103504766dbc..0c976c93e258fc072c923084628a077099c0dd39 100644 (file)
--- a/doc/src/sgml/ref/set_constraints.sgml
+++ b/doc/src/sgml/ref/set_constraints.sgml
@@ -1,4 +1,4 @@
-
+
 
  
   SET CONSTRAINTS
@@ -7,7 +7,7 @@
 
  
   SET CONSTRAINTS
-  set the constraint mode of the current transaction
+  set constraint checking modes for the current transaction
  
 
  
@@ -25,28 +25,40 @@ SET CONSTRAINTS { ALL | name [, ...
 
   
    SET CONSTRAINTS sets the behavior of constraint
-   evaluation in the current transaction. In
-   IMMEDIATE mode, constraints are checked at the
-   end of each statement. In DEFERRED mode,
-   constraints are not checked until transaction commit.
+   checking within the current transaction. IMMEDIATE
+   constraints are checked at the end of each
+   statement. DEFERRED constraints are not checked until
+   transaction commit.  Each constraint has its own
+   IMMEDIATE or DEFERRED mode.
   
 
   
-   When you change the mode of a constraint to be
-   IMMEDIATE, the new constraint mode takes effect
-   retroactively: any outstanding data modifications that would have
-   been checked at the end of the transaction (when using
-   DEFERRED) are instead checked during the
-   execution of the SET CONSTRAINTS command.
-  
-
-  
-   Upon creation, a constraint is always give one of three
+   Upon creation, a constraint is given one of three
    characteristics: INITIALLY DEFERRED,
    INITIALLY IMMEDIATE DEFERRABLE, or
    INITIALLY IMMEDIATE NOT DEFERRABLE. The third
    class is not affected by the SET CONSTRAINTS
-   command.
+   command.  The first two classes start every transaction in the
+   indicated mode, but their behavior can be changed within a transaction
+   by SET CONSTRAINTS.
+  
+
+  
+   SET CONSTRAINTS with a list of constraint names changes
+   the mode of just those constraints (which must all be deferrable).  If
+   there are multiple constraints matching any given name, all are affected.
+   SET CONSTRAINTS ALL changes the mode of all deferrable
+   constraints.
+  
+
+  
+   When you change the mode of a constraint from DEFERRED
+   to IMMEDIATE, the new mode takes effect
+   retroactively: any outstanding data modifications that would have
+   been checked at the end of the transaction are instead checked during the
+   execution of the SET CONSTRAINTS command.
+   If any such constraint is violated, the SET CONSTRAINTS
+   fails (and does not change the constraint mode).
   
 
   
@@ -81,6 +93,14 @@ SET CONSTRAINTS { ALL | name [, ...
    PostgreSQL, it only applies to
    foreign-key constraints.
   
+
+  
+   The SQL standard says that constraint names appearing in SET
+   CONSTRAINTS can be schema-qualified.  This is not yet
+   supported by PostgreSQL: the names must
+   be unqualified, and all constraints matching the command will be
+   affected no matter which schema they are in.
+