MySQL stored procedure not working on Mac OS X - mysql

Question

I have the following stored procedure (Taken from a comment on http://dev.mysql.com/doc/refman/5.0/en/create-index.html, used to check if an index exists on a table):
DELIMITER $$
DROP PROCEDURE IF EXISTS `create_index_if_not_exists`$$
CREATE DEFINER=`user`#`%` PROCEDURE `create_index_if_not_exists`(table_name_vc varchar(50), index_name_vc varchar(50), field_list_vc varchar(200))
SQL SECURITY INVOKER
BEGIN
set #Index_cnt = (
select count(1) cnt
FROM INFORMATION_SCHEMA.STATISTICS
WHERE table_name = table_name_vc
and index_name = index_name_vc
);
IF ifnull(#Index_cnt,0) = 0 THEN set #index_sql = concat('Alter table ',table_name_vc,' ADD INDEX ',index_name_vc,'(',field_list_vc,');');
PREPARE stmt FROM #index_sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END IF;
END$$
DELIMITER ;
The strange thing is that it works perfectly on CentOS 5.4 with MySQL 5.5.25, but does not work on Mac OS X 10.8.1 with MySQL 5.5.24. On Mac, the #Index_cnt is always 0 if I add
select #Index_cnt
in the stored procedure. If I do the SELECT COUNT(1) cnt ... statement on it's own, then 1 or 0 is returned as it should be.
Any ideas?

Answer 1

I have re-written the stored procedure and this now works on all platforms:
DELIMITER $$
DROP PROCEDURE IF EXISTS myschema.create_index_if_not_exists $$
CREATE PROCEDURE myschema.create_index_if_not_exists(in p_tableName VARCHAR(128), in p_indexName VARCHAR(128), in p_columnName VARCHAR(128) )
BEGIN
PREPARE stmt FROM 'SELECT #indexCount := COUNT(1) from information_schema.statistics WHERE `table_name` = ? AND `index_name` = ?';
SET #table_name = p_tableName;
SET #index_name = p_indexName;
EXECUTE stmt USING #table_name, #index_name;
DEALLOCATE PREPARE stmt;
-- select #indexCount;
IF( #indexCount = 0 ) THEN
SELECT 'Creating index';
SET #createIndexStmt = CONCAT('CREATE INDEX ', p_indexName, ' ON ', p_tableName, ' ( ', p_columnName ,')');
PREPARE stmt FROM #createIndexStmt;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END IF;
END $$
DELIMITER ;
Use it as follows:
call myschema.create_index_if_not_exists('MyTable','end_time_index','end_time');
This was tested on MAC OS X 10.8.2 with MySQL 5.5.24 and on Windows 7 with MySQL 5.5.21