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Creating synthetic data sets for tuning SQL queries

oli.sennhauser@fromdual.com (Oli Sennhauser) — Fri, 02 Oct 2020 16:50:33 +0000

When it comes to SQL Query tuning with customers we often get the slow running SQL query and possibly, in good cases, also the table structure. But very often, for various reasons, we do not get the data.

Find evil developer habits with log_queries_not_using_indexes

oli.sennhauser@fromdual.com (Oli Sennhauser) — Wed, 20 Sep 2017 16:00:03 +0000

Recently I switched on the MariaDB slow query logging flag log_queries_not_using_indexes just for curiosity on one of our customers systems:

Why you should take care of MySQL data types

oli.sennhauser@fromdual.com (Oli Sennhauser) — Wed, 25 May 2016 11:42:20 +0000

A customer reported last month that MySQL does a full table scan (FTS) if a query was filtered by a INT value on a VARCHAR column. First I told him that this is not true any more because MySQL has fixed this behaviour long time ago. He showed me that I was wrong: