Add mention of functional indexes for case-insensitive comparisons.

diff --git a/doc/src/FAQ/FAQ.html b/doc/src/FAQ/FAQ.html
index 3e4a0d9b2e64ab84e12979a9bdf16b46ffe5214b..8904661782c314139ca954869b411c04cb8fc4d9 100644 (file)
--- a/doc/src/FAQ/FAQ.html
+++ b/doc/src/FAQ/FAQ.html
@@ -112,7 +112,8 @@
      4.11) What is an R-tree index?
      4.12) What is the Genetic Query Optimizer?
      4.13) How do I perform regular expression
-    searches and case-insensitive regular expression searches?
+    searches and case-insensitive regular expression searches? How do I
+    use an index for case-insensitive searches?
      4.14) In a query, how do I detect if a field
     is NULL?
      4.15) What is the difference between the
@@ -957,13 +958,29 @@ Maximum number of indexes on a table?    unlimited
     search.
 
     4.13) How do I perform regular expression
-    searches and case-insensitive regular expression searches?
+    searches and case-insensitive regular expression searches?  How do I
+    use an index for case-insensitive searches?
 
     The ~ operator does regular expression matching, and
     ~* does case-insensitive regular expression matching. The
     case-insensitive variant of LIKE is called
     ILIKE in PostgreSQL 7.1 and later.
 
+    Case-insensitive equality comparisons are normally expressed as:
+    
+    
+    SELECT *
+    FROM tab
+    WHERE lower(col) = 'abc'
+    
+
+    This will not use an standard index. However, if you create a
+    functional index, it will be used:
+
+    
+    CREATE INDEX tabindex on tab (lower(col));
+    
+
     4.14) In a query, how do I detect if a field
     is NULL?