February 2012
Intermediate to advanced
266 pages
8h
English
Content preview from MySQL TroubleshootingBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
Localizing the Problem (Minimizing the Test Case)
I already showed the value of minimizing a test case in Single Server Example, where I reduced an incorrect SELECT to a CREATE
TABLE that reproduced the wrong parameters. Here I will discuss
the principle of a minimal test case in more general terms.
As an example, take the following huge query[22]:
SELECT IF(TABLE1.FIELD1 = 'R' AND TABLE1.FIELD2 IS NOT NULL AND TABLE1.FIELD3 = '1' AND TABLE2.FIELD4 = TABLE2.FIELD5 AND TABLE3.FIELD6 = TABLE4.FIELD6, TABLE3.FIELD7, TABLE4.FIELD7) AS ALIAS1, IF(TABLE1.FIELD1 = 'R' AND TABLE1.FIELD2 IS NOT NULL AND TABLE1.FIELD3 = '1' AND TABLE2.FIELD4 = TABLE2.FIELD5 AND TABLE3.FIELD6 = TABLE4.FIELD6, TABLE3.FIELD8, TABLE4.FIELD8) AS ALIAS2, SUM( IF ( (SELECT TABLE5.FIELD7 FROM TABLE4 ALIAS3, TABLE2 ALIAS4, TABLE4 ALIAS5 WHERE TABLE5.FIELD5 = ALIAS4.FIELD4 AND ALIAS4.FIELD5 = ALIAS5.FIELD5 AND ALIAS5.FIELD7 = FIELD9 AND TABLE5.FIELD6 = TABLE6.FIELD7 LIMIT 1 ) IS NULL, 0, TABLE7.FIELD10/TABLE7.FIELD11) ) AS ALIAS11 FROM TABLE4 ,TABLE4 ALIAS6, TABLE8 , TABLE4 ALIAS7, TABLE9 , TABLE7 , TABLE2 , TABLE1 FORCE INDEX(FIELD12) LEFT JOIN TABLE1 ALIAS8 ON TABLE1.FIELD13 = TABLE10.FIELD13 LEFT JOIN TABLE1 ALIAS9 ON ALIAS9.FIELD13 = TABLE10.FIELD2 LEFT JOIN TABLE4 ALIAS10 ON ALIAS10.DFIELD5 = TABLE3.FIELD5 WHERE TABLE1.FIELD14 > DATE_sub(now(), INTERVAL 16 DAY) and TABLE1.FIELD1 IN ('P', 'R','D') AND TABLE1.DFIELD5 = TABLE4.FIELD5 AND TABLE1.FIELD15 = TABLE8.FIELD16 AND TABLE6.FIELD7 = TABLE8.FIELD17 AND TABLE4.FIELD18 ...Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.