Because I do a lot of Performance Tuning gigs I get often in contact with these status variables. In the beginning I had a problem to understand them and now I have a problem to memorize the relation of the name and the meaning. Therefore I wrote this little summary:
Prepare the example
To show you the effect I have worked out a little example:
CREATE TABLE test (
id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY
, data VARCHAR(32)
, ts TIMESTAMP
, INDEX (data)
);
INSERT INTO test
VALUES …
