Mysql Innodb indexing on a column with majority null values
Question
I tried to index a date time field in a table with 20 million rows. Majority(99%) of the rows for that column are null. After that, CPU utilization shot up to 100% because of this. I'm not able to find out the exact reason for the same.
1 answers
solution1
0 2016-08-01 22:55:45
As an optimization, InnoDB "delays" the updating of indexes. Probably what happened is that this delayed operation is happening, causing the CPU to spike.
For further info, search for "InnoDB change buffering".
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