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In the article he mentions that MySQL still uses MyISAM for temporary tables, which were being created by the query he was running (which, granted, did SELECT *
by chrisbolt 15y ago
In the article he mentions that MySQL still uses MyISAM for temporary tables, which were being created by the query he was running (which, granted, did SELECT * which is usually a bad idea). If the size of the temporary table was the cause of slowness, wouldn't it affect InnoDB and MyISAM tables equally?
- nerfhammer 15y agoIt would seem so. It would probably always have been creating on-disk temporary tables because text columns aren't permitted in memory tables. It was probably just that the fixed-length row format forced them to become extremely large. The performance advantage that he expected from the schema change would only arguably make sense with respect to whatever storage engine he was using, and it's actually not really true for InnoDB. [Actually come to think of it I can't think of any advantage do doing it for MyISAM either, I don't think it has a concept of overflow pages. InnoDB 1.1 has a lot of performance enhancements for text/blob columns, though...]