Mysql query optimization takes more than 30 sec - mysql

Question

Hi friends can any one please help me to optimize this query ,it takes more than 30 sec.
any suggestion is warmly welcome.
Query :
SELECT
CONCAT(CCD.CONTACT_FIRST_NAME, ' ', CCD.CONTACT_LAST_NAME) AS NAME,
A.EMAIL_IDS,
CCD.UNSUBSCRIBE,
IFNULL(CSL.LOG_DATE, '') AS LOG_DATE,
CSL.IP_ADDRESS,
IF(CSL.BROWSER IS NULL, '', CSL.BROWSER) AS BROWSER,
(CASE
WHEN (UNSUBSCRIBE = 0 OR UNSUBSCRIBE IS NULL) THEN 'Opted In'
ELSE (CASE
WHEN (UNSUBSCRIBE = 1) THEN 'Opted Out'
ELSE (CASE
WHEN
((UNSUBSCRIBE = 2 OR UNSUBSCRIBE = 3)
AND CCD.CONTACT_ID NOT IN (SELECT
CONTACT_ID
FROM
CM_SUBSCRIPTION_MAIL_DATA
WHERE
IS_MAIL_SENT = 'Y'))
THEN
'Opt-In Request not Sent'
ELSE 'Opt-In Pending'
END)
END)
END) AS CURR_SUB,
(CASE
WHEN (SUBSCRIBE_FROM = 0) THEN 'Opted In'
ELSE (CASE
WHEN (SUBSCRIBE_FROM = 1) THEN 'Opted Out'
ELSE (CASE
WHEN (SUBSCRIBE_FROM = 2 OR SUBSCRIBE_FROM = 3) THEN 'Opt-In Pending'
ELSE ''
END)
END)
END) AS SUB_FROM,
SUBSCRIBE_FROM,
(CASE
WHEN (SUBSCRIBE_TO = 0) THEN 'Opted In'
ELSE (CASE
WHEN (SUBSCRIBE_TO = 1) THEN 'Opted Out'
ELSE (CASE
WHEN (SUBSCRIBE_TO = 2 OR SUBSCRIBE_TO = 3) THEN 'Opt-In Pending'
ELSE ''
END)
END)
END) AS SUB_TO,
SUBSCRIBE_TO
FROM
CM_CONTACT_DETAILS CCD
LEFT JOIN
ADDRESS A ON CCD.CONTACT_ID = A.FOREIGN_ID
LEFT JOIN
CM_SUBSCRIPTION_LOGS CSL ON CSL.CONTACT_ID = CCD.CONTACT_ID
WHERE
1 = 1
GROUP BY CSL.LOG_DATE , CCD.CONTACT_ID
ORDER BY NAME DESC , LOG_DATE DESC
LIMIT 0 , 20

Answer 1

Your case/when can be simplified, but I believe the killer of your query was the correlated NOT IN SELECT clause for your Opt-in request not sent.
I've change your query to do a left-join to your mailing table based on the contact AND the mailed status of "Y". So this simplifies your case to only have to check for IS NULL of the mailing table contact ID.
You can't do too much on performance since your Group by is by columns from different tables that won't take advantage of any index optimization, then all that ordered by the name makes it more of an issue... but the correlated subquery per the field being executed every time to a left-join SHOULD help.
SELECT
CONCAT(CCD.CONTACT_FIRST_NAME, ' ', CCD.CONTACT_LAST_NAME) AS NAME,
A.EMAIL_IDS,
CCD.UNSUBSCRIBE,
IFNULL(CSL.LOG_DATE, '') AS LOG_DATE,
CSL.IP_ADDRESS,
IF(CSL.BROWSER IS NULL, '', CSL.BROWSER) AS BROWSER,
CASE WHEN UNSUBSCRIBE = 0 OR UNSUBSCRIBE IS NULL THEN 'Opted In'
WHEN UNSUBSCRIBE = 1 THEN 'Opted Out'
WHEN UNSUBSCRIBE IN (2,3) AND SMD.CONTACT_ID IS NULL THEN 'Opt-In Request not Sent'
ELSE 'Opt-In Pending' END AS CURR_SUB,
CASE WHEN SUBSCRIBE_FROM = 0 THEN 'Opted In'
WHEN SUBSCRIBE_FROM = 1 THEN 'Opted Out'
WHEN SUBSCRIBE_FROM = 2 OR SUBSCRIBE_FROM = 3 THEN 'Opt-In Pending'
ELSE '' END AS SUB_FROM,
SUBSCRIBE_FROM,
CASE WHEN SUBSCRIBE_TO = 0 THEN 'Opted In'
WHEN SUBSCRIBE_TO = 1 THEN 'Opted Out'
WHEN SUBSCRIBE_TO = 2 OR SUBSCRIBE_TO = 3 THEN 'Opt-In Pending'
ELSE '' END AS SUB_TO,
SUBSCRIBE_TO
FROM
CM_CONTACT_DETAILS CCD
LEFT JOIN ADDRESS A
ON CCD.CONTACT_ID = A.FOREIGN_ID
LEFT JOIN CM_SUBSCRIPTION_LOGS CSL
ON CSL.CONTACT_ID = CCD.CONTACT_ID
LEFT JOIN CM_SUBSCRIPTION_MAIL_DATA SMD
ON CCD.CONTACT_ID = SMD.CONTACT_ID
AND IS_MAIL_SENT = 'Y'
WHERE
1 = 1
GROUP BY
CSL.LOG_DATE,
CCD.CONTACT_ID
ORDER BY
NAME DESC,
LOG_DATE DESC
LIMIT
0, 20