CITEXT Data Type 2.00

This distribution creates a custom PostgreSQL data type, CITEXT, a locale- aware, case-insensitve TEXT type for PostgreSQL 8.3. Essentially, it internally calls LOWER() when comparing values. Otherwise, it behaves exactly like TEXT.

The standard approach to doing case-insensitive matches in PostgreSQL has been to use the LOWER() function in your queries, something like this:

SELECT *
FROM tab
WHERE lower(col) = LOWER(?);

This works reasonably well, but has a number of drawbacks:

  • It makes your SQL statements verbose, and you always have to remember to use LOWER() on both the column and on the query value (so that both use the same collations).
  • It won't use an index, unless you create a functional index using LOWER().
  • You can't have a case-insensitive primary key without creating two unique indexes, one for the primary key (implicitly created) and a functional index using LOWER().

The CITEXT data type allows you to replace all the calls to LOWER() in client code that wants to perform case-insensitive queries, while also allowing a primary key to be case-insensitive. CITEXT is multibyte aware, just like TEXT, which means that the comparison of uppercase and lowercase characters is dependent on the rules in the LC_COLLATE locale setting. Again, this behavior is identical to the use of LOWER() in queries. But because it's done in C and is transparent, you don't have to remember to do anything special in your queries.

Installation

To install the CITEXT data type, make sure that pg_xs is in your path, and then type these commands:

export USE_PGXS=1 make make install make installcheck

If you encounter an error such as:

"Makefile", line 8: Need an operator

You need to use GNU make, which may well be installed on your system as 'gmake':

gmake gmake install gmake installcheck

If you encounter an error such as:

make: pg_config: Command not found

Be sure that you have pg_config installed and in your path. If you used a package management system such as RPM to install PostgreSQL, be sure that the -devel package is also installed. If necessary, add the path to pg_config to your $PATH environment variable:

export PATH=$PATH:/path/to/pgsql/bin make make install make installcheck

And finally, if all that fails, copy the entire distribution directory to the 'contrib' subdirectory of the PostgreSQL source code and try it there using these commands:

make make install make installcheck

Note that the tests run by the installcheck target expect the locale to be en_US.UTF-8, so there could potentially be some failures if you're using a different locale.

Once everything is installed, go ahead and add the citext data type to your database:

psql -f citext.sql [db_name]

Usage

Once you've installed the CITEXT data type, you can start using it in your database.

CREATE TABLE users ( nick CITEXT, pass TEXT );

INSERT INTO users VALUES ( 'larry', md5(random()::text) ); INSERT INTO users VALUES ( 'Tom', md5(random()::text) ); INSERT INTO users VALUES ( 'Damian', md5(random()::text) ); INSERT INTO users VALUES ( 'NEAL', md5(random()::text) ); INSERT INTO users VALUES ( 'Bjørn', md5(random()::text) ); INSERT INTO users VALUES ( '☺唐鳳☻', md5(random()::text) );

If you ever need to install the data type into another database, you'll find 'citext.sql' in the 'share/contrib' subdirectory of your PostgreSQL server directory. This 'README.citext' file will be in the 'doc/contrib' subdirectory.

Suported Platforms

This package uses PostgreSQL's build tools for easy cross-platform build suport. It is therefore designed to build and install on any platform that supports PostgreSQL. It is known to work on the following platforms and operating systems.

  • Darwin 9.3.0 i386

If you know of others, please submit them! Use uname -mrs to get the formal OS and hardware names.

Author

David E. Wheeler david@kineticode.com

Inspired by CITEXT 1.0 by Donald Fraser.

Copyright and License

Copyright (c) 2008-2011 David E. Wheeler. Some rights reserved.

Permission to use, copy, modify, and distribute this software and its documentation for any purpose, without fee, and without a written agreement is hereby granted, provided that the above copyright notice and this paragraph and the following two paragraphs appear in all copies.

IN NO EVENT SHALL KINETICODE BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF KINETICODE HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

KINETICODE SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND KINETICODE HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.