Thesql information schema database last used datetime

information-schemaMySQL

I have a lot of tables in my database, almost 1,000. Most of them I am not using now.

Is there any way to know from the information schema tables when I have last used my tables?

Best Answer

No, that information is not available on INFORMATION_SCHEMA (it only stores metadata).

There are several options that I can recommend you:

  • The user stats plugin from Google: after installed and enabled, it will not tell you the last time a table was accessed, but it will tell you how many times it was
  • Using the slow log: you can activate the slow log and set long_query_time = 0 (be careful of the extra overhead and disk space and then analyze per table used, so you can detect the last time it was used. Tools like pt-query-digest --review aggregate by query, not by table, but they may be useful to look for specific queries.
  • With an audit plugin you can fine-tune what you register better than with the slow log, by activating it only for certain queries or objects.
  • The performance schema can gather information about everything, but you may need MySQL 5.6 and the configuration can be a bit cumbersome

All of them will tell you information since the point you activate them, and not past information. UNIX atime is very unreliable for access time, but you may also want to give that a try, depending on the engine.

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