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Author Topic: SQL Query Slow (Suggestions)  (Read 1283 times)

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Offline shuban

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SQL Query Slow (Suggestions)
« on: July 09, 2018, 11:58:04 am »
I posted this on the main SMF forum, but didn't get a favorable response. Was hoping to get SMFHack's expertise.

Code: [Select]
SELECT
mso.subject AS first_subject, ml.ID_MSG, mso.ID_MSG AS id_msg_first, ml.posterTime AS first_poster_time, t.ID_TOPIC, t.ID_BOARD, b.name AS bname,
t.numReplies, t.numViews, t.ID_MEMBER_STARTED AS id_first_member, ml.ID_MEMBER AS id_last_member,
ml.posterTime AS last_poster_time, mso.posterName AS first_poster_name,
IFNULL(meml.realName, ml.posterName) AS last_poster_name, ml.subject AS last_subject,
ml.icon AS last_icon, mso.icon AS first_icon,t.ID_POLL, t.isSticky, t.locked, ml.modifiedTime AS last_modified_time,
CASE WHEN IFNULL(lt.ID_MSG, IFNULL(lmr.ID_MSG, 0)) < t.ID_LAST_MSG THEN 1 ELSE 0 END AS is_new, SUBSTRING(ml.body, 1, 385) AS last_body,
SUBSTRING(mso.body, 1, 385) AS first_body, ml.smileysEnabled AS last_smileys, mso.smileysEnabled AS first_smileys, t.ID_FIRST_MSG, t.ID_LAST_MSG
FROM smf_topics AS t
INNER JOIN smf_messages AS ml ON (ml.ID_MSG = t.ID_LAST_MSG)
INNER JOIN smf_messages AS mso ON (mso.ID_MSG = t.ID_FIRST_MSG)
LEFT JOIN smf_boards AS b ON (b.ID_BOARD = ml.ID_BOARD)
LEFT JOIN smf_members AS meml ON (meml.ID_MEMBER = ml.ID_MEMBER)
LEFT JOIN smf_log_topics AS lt ON (lt.ID_TOPIC = ml.ID_TOPIC AND lt.ID_MEMBER = 6)
LEFT JOIN smf_log_mark_read AS lmr ON (lmr.ID_BOARD = t.ID_BOARD AND lmr.ID_MEMBER = 6)
WHERE t.ID_BOARD IN (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 17, 20, 21, 22, 23, 24, 25, 33, 34, 35, 38, 41, 43, 48, 49, 50, 55, 59, 61, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 95, 96, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117)
AND t.ID_LAST_MSG >= 4708323 AND ml.posterTime > unix_timestamp(now() - interval 14 day)
ORDER BY t.ID_LAST_MSG DESC
LIMIT 0, 40

Sometimes takes a minute to load, what gives?

Offline SMFHacks

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Re: SQL Query Slow (Suggestions)
« Reply #1 on: July 09, 2018, 12:10:29 pm »
Can post the results of 
describe smf_messages;

And also run
Code: [Select]
explain SELECT
mso.subject AS first_subject, ml.ID_MSG, mso.ID_MSG AS id_msg_first, ml.posterTime AS first_poster_time, t.ID_TOPIC, t.ID_BOARD, b.name AS bname,
t.numReplies, t.numViews, t.ID_MEMBER_STARTED AS id_first_member, ml.ID_MEMBER AS id_last_member,
ml.posterTime AS last_poster_time, mso.posterName AS first_poster_name,
IFNULL(meml.realName, ml.posterName) AS last_poster_name, ml.subject AS last_subject,
ml.icon AS last_icon, mso.icon AS first_icon,t.ID_POLL, t.isSticky, t.locked, ml.modifiedTime AS last_modified_time,
CASE WHEN IFNULL(lt.ID_MSG, IFNULL(lmr.ID_MSG, 0)) < t.ID_LAST_MSG THEN 1 ELSE 0 END AS is_new, SUBSTRING(ml.body, 1, 385) AS last_body,
SUBSTRING(mso.body, 1, 385) AS first_body, ml.smileysEnabled AS last_smileys, mso.smileysEnabled AS first_smileys, t.ID_FIRST_MSG, t.ID_LAST_MSG
FROM smf_topics AS t
INNER JOIN smf_messages AS ml ON (ml.ID_MSG = t.ID_LAST_MSG)
INNER JOIN smf_messages AS mso ON (mso.ID_MSG = t.ID_FIRST_MSG)
LEFT JOIN smf_boards AS b ON (b.ID_BOARD = ml.ID_BOARD)
LEFT JOIN smf_members AS meml ON (meml.ID_MEMBER = ml.ID_MEMBER)
LEFT JOIN smf_log_topics AS lt ON (lt.ID_TOPIC = ml.ID_TOPIC AND lt.ID_MEMBER = 6)
LEFT JOIN smf_log_mark_read AS lmr ON (lmr.ID_BOARD = t.ID_BOARD AND lmr.ID_MEMBER = 6)
WHERE t.ID_BOARD IN (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 17, 20, 21, 22, 23, 24, 25, 33, 34, 35, 38, 41, 43, 48, 49, 50, 55, 59, 61, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 95, 96, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117)
AND t.ID_LAST_MSG >= 4708323 AND ml.posterTime > unix_timestamp(now() - interval 14 day)
ORDER BY t.ID_LAST_MSG DESC
LIMIT 0, 40;

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Offline shuban

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Re: SQL Query Slow (Suggestions)
« Reply #2 on: July 09, 2018, 12:22:38 pm »
The explain gives:

While the describe gives:



Offline SMFHacks

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Re: SQL Query Slow (Suggestions)
« Reply #3 on: July 09, 2018, 12:28:32 pm »
You need to add an index on postertime

ALTER table smf_messages add index posterTime (posterTime);
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Offline shuban

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Re: SQL Query Slow (Suggestions)
« Reply #4 on: July 09, 2018, 12:39:30 pm »
You need to add an index on postertime

ALTER table smf_messages add index posterTime (posterTime);

How did you determine that?

Offline SMFHacks

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Re: SQL Query Slow (Suggestions)
« Reply #5 on: July 09, 2018, 12:41:32 pm »
Was used in the where clause and I saw no index was on that column
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Offline shuban

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Re: SQL Query Slow (Suggestions)
« Reply #6 on: July 09, 2018, 01:02:18 pm »
It now loads in less than 1 second.

I noticed the KEY is now mul. I presume that's what was altered. How come SMF doesn't come stock that way?

Offline SMFHacks

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Re: SQL Query Slow (Suggestions)
« Reply #7 on: July 09, 2018, 01:08:59 pm »
Yes that was altered.
It might in new versions.
SMF only adds indexes to columns that are used in the where clause. Postertime might not have been used anywhere before.
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Offline shuban

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Re: SQL Query Slow (Suggestions)
« Reply #8 on: August 02, 2018, 08:21:02 pm »
I'm curious, does this need to be done every once in a while?

Offline SMFHacks

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Re: SQL Query Slow (Suggestions)
« Reply #9 on: August 02, 2018, 08:22:10 pm »
Index only has to be added once.
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Offline shuban

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Re: SQL Query Slow (Suggestions)
« Reply #10 on: August 02, 2018, 10:07:47 pm »
Index only has to be added once.

Reason why I asked is because suddenly it started going slow again :-\ Prior, it would load in less than a second. Nothing has changed, coding wise.
« Last Edit: August 02, 2018, 10:12:49 pm by shuban »

 

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