Document the longstanding behavior of LIMIT NULL and OFFSET NULL,

per gripe from David Wheeler that this was mentioned nowhere.
In passing, editorialize a bit on the description of the SQL:2008
equivalent syntax.

diff --git a/doc/src/sgml/ref/select.sgml b/doc/src/sgml/ref/select.sgml
index a33a537bd484d5bc0e5c076fae1c31e16d4f5e51..ff5d68126042b65e39128c93426a677c0b6eb1ab 100644 (file)
--- a/doc/src/sgml/ref/select.sgml
+++ b/doc/src/sgml/ref/select.sgml
@@ -1,5 +1,5 @@
 
 
@@ -1002,6 +1002,13 @@ OFFSET start
     class="parameter">count rows to be returned.
    
 
+   
+    If the count expression
+    evaluates to NULL, it is treated as LIMIT ALL, i.e., no
+    limit.  If start evaluates
+    to NULL, it is treated the same as OFFSET 0.
+   
+
    
     SQL:2008 introduced a different syntax to achieve the same thing,
     which PostgreSQL also supports.  It is:
@@ -1014,10 +1021,11 @@ FETCH { FIRST | NEXT } [ count ] {
     the FETCH clause.  ROW
     and ROWS as well as FIRST
     and NEXT are noise words that don't influence
-    the effects of these clauses.  When using expressions other than
-    constants for the offset or fetch count, parentheses will be
-    necessary in most cases.  If the fetch count is omitted, it
-    defaults to 1.
+    the effects of these clauses.  In this syntax, when using expressions
+    other than simple constants for start
+    or count, parentheses will be
+    necessary in most cases.  If count is
+    omitted in FETCH, it defaults to 1.