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I can confirm that the query optimizer introduced a rather serious bug (significantly suboptimal plan for queries involving low cardinality indices), which caus

I can confirm that the query optimizer introduced a rather serious bug (significantly suboptimal plan for queries involving low cardinality indices), which caused serious issues in our system. This, in addition to the fact that index merging has been broken in MySQL 5.6 for more than an year now (in some cases it will cause empty resultsets to be returned), and that it is still broken on MySQL 5.7

dubbel 10y ago
Do you happen to have a link to the bug report for the first issue you described? I'm wondering whether I saw a similar thing in a benchmark I tested.
- pizza234 10y ago
  Sorry, don't have it. We experienced three separate instances of it, and have to open a report yet.