By specifying USE INDEX (index_list), you can tell MySQL to use only one of the named indexes to find rows in the table.Do not use force index on simple queries like this one. There is a reason MySQL is not using the index.

I have this query (below) which keeps hitting the table when it should be using the created index. Is there something simple I'm missing here? How can I get it to use the index instead of the table?

A full table scan is what happens when MySQL reads every row in a table to resolve a query. Missing indexes cause it, but it also occurs when the optimizer decides an existing index isn't worth using — or when query patterns structurally prevent index use.

The indices come from the left, which you’re doing well with WHERE, but you use ORDER this isn’t the case. Since you’re doing order on time_reverse, you’re trying to come from the right, skipping over the first two columns in the index.

By turning off use_index_extensions, MySQL will not take advantage of the primary key part of the index, and there will be a single range scan over all records with the given grid_id. The disadvantage is that MySQL will have to do a look-up into the base table for every row in that range.

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What index are we talking about here? I’m surprised that if the expression colBoolean evaluates to true, MySQL would treat it differently than an explicit check with = 1. Could you please share the column definition for said table and the version of MySQL which you are using?

Following query is issued every time we tag something and looks like AATO calls SQL lower function, which in turn makes Mysql not use index on "name" column. mysql> EXPLAIN SELECT tags.*

Run EXPLAIN to confirm MySQL is using an index-based join instead of scanning both tables. If one side is missing an index, add it there first, since that’s the most common cause of slow joins. What causes a MySQL query to run slow only sometimes?

Binary package hint: dbmail Using current DBMail (2.2.11 as packaged or 2.2.13 from upstream) with the current MySQL server version (5.1) shipped with Ubuntu is unusable. The MySQL server does not use the index and falls back to a full table scan.