How to speed up the SELECT query of the following table? - php

Question

I have a mysql table whose create code is as follows :
CREATE TABLE image_ref (
region VARCHAR(50) NULL DEFAULT NULL,
district VARCHAR(50) NULL DEFAULT NULL,
district_name VARCHAR(100) NULL DEFAULT NULL,
lot_no VARCHAR(10) NULL DEFAULT NULL,
sp_no VARCHAR(10) NULL DEFAULT NULL,
name VARCHAR(200) NULL DEFAULT NULL,
form_no VARCHAR(50) NOT NULL DEFAULT '',
imagename VARCHAR(50) NULL DEFAULT NULL,
updated_by VARCHAR(50) NULL DEFAULT NULL,
update_log DATETIME NULL DEFAULT NULL,
ip VARCHAR(50) NULL DEFAULT NULL,
imgfetchstat VARCHAR(1) NULL DEFAULT NULL,
PRIMARY KEY (form_no)
)
COLLATE='latin1_swedish_ci'
ENGINE=MyISAM;
This table contains approximately 7,00,000 number of rows. I have an application developed using PHP. Somewhere I need to run the following query :
SELECT
min(imagename) imagename
FROM
image_ref
WHERE
district_name = '$sess_district'
AND
lot_no = '$sess_lotno'
AND
imgfetchstat = '0';
which is taking on average 1.560 sec. The form_no field only has unique values. After some job is done with the result set fetched, the imgfetchstat is required to be updated with a value 1. Now my requirement is that, whether I should use InnoDB or MyISAM? Also, the application is accessed by around 50 numbers of users in LAN. Is there any way out to run the above query little bit faster? because the imagename fetched is being used to load an image of resolution 500 x 498 into the browser and the it is taking enough time to load the image. Thanks in advance.

Answer 1

You can add indexes to your table (be aware that this will make the storage larger - but given your query, you should be able to use the following:
ALTER TABLE `table` ADD INDEX `product_id` (`product_id`)
For more information see http://dev.mysql.com/doc/refman/5.0/en/create-index.html
You can add an index on a single column (which makes things nice for the DB, even it it uses a few of them on a query) but if you have a secific query that needs to REALLY run fast, you can add a multi-column index which is specific to your query:
ALTER TABLE image_ref ADD INDEX `someName`
(`district_name`, `lot_no`, `imgfetchstat`)