@@ -112,7 +112,8 @@ <H2>Operational Questions</H2>
112112< A href ="#4.11 "> 4.11</ A > ) What is an R-tree index?< BR >
113113< A href ="#4.12 "> 4.12</ A > ) What is the Genetic Query Optimizer?< BR >
114114< A href ="#4.13 "> 4.13</ A > ) How do I perform regular expression
115- searches and case-insensitive regular expression searches?< BR >
115+ searches and case-insensitive regular expression searches? How do I
116+ use an index for case-insensitive searches?< BR >
116117< A href ="#4.14 "> 4.14</ A > ) In a query, how do I detect if a field
117118 is< SMALL > NULL</ SMALL > ?< BR >
118119< A href ="#4.15 "> 4.15</ A > ) What is the difference between the
@@ -957,13 +958,29 @@ <H4><A name="4.12">4.12</A>) What is the Genetic Query
957958 search.</ P >
958959
959960< H4 > < A name ="4.13 "> 4.13</ A > ) How do I perform regular expression
960- searches and case-insensitive regular expression searches?</ H4 >
961+ searches and case-insensitive regular expression searches? How do I
962+ use an index for case-insensitive searches?</ H4 >
961963
962964< P > The< I > ~</ I > operator does regular expression matching, and
963965< I > ~*</ I > does case-insensitive regular expression matching. The
964966 case-insensitive variant of< SMALL > LIKE</ SMALL > is called
965967< SMALL > ILIKE</ SMALL > in PostgreSQL 7.1 and later.</ P >
966968
969+ < P > Case-insensitive equality comparisons are normally expressed as:
970+
971+ < PRE >
972+ SELECT *
973+ FROM tab
974+ WHERE lower(col) = 'abc'
975+ </ PRE >
976+
977+ This will not use an standard index. However, if you create a
978+ functional index, it will be used:
979+
980+ < PRE >
981+ CREATE INDEX tabindex on tab (lower(col));
982+ </ PRE >
983+
967984< H4 > < A name ="4.14 "> 4.14</ A > ) In a query, how do I detect if a field
968985 is< SMALL > NULL</ SMALL > ?</ H4 >
969986