Document that COUNT(*) might not need a seq scan any more.

Noted by Josh Kupershmidt.

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 219ba9abf39d946d85246d33f83b571896624e3c..ec1400408436e9d0aa221060ef2dd3f02109c74d 100644 (file)
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -11102,8 +11102,10 @@ SELECT b1 = ANY((SELECT b2 FROM t2 ...)) FROM t1 ...;
 
 SELECT count(*) FROM sometable;
 
-    will be executed by PostgreSQL using a
-    sequential scan of the entire table.
+    will require effort proportional to the size of the table:
+    PostgreSQL will need to scan either the
+    entire table or the entirety of an index which includes all rows in
+    the table.