WL#10824: Remove query cache
Affects: Server-8.0 — Status: Complete — Priority: Medium
We've decided to remove the query cache for 8.0 (it will be deprecated in 5.7, which this worklog does not concern itself with). The proposed design: * HAVE_QUERY_CACHE will now return NO, so that well-behaved clients can check for this and behave accordingly. * The SQL_NO_CACHE keyword will continue to exist, but will be ignored (no effect in the grammar). This is so that e.g. mysqldump can continue working. (SQL_CACHE will be removed as a token.) * The RESET QUERY CACHE and FLUSH QUERY CACHE statements will be removed. Trying to use them will return errors. * All query cache command-line options will be removed. Trying to set them will return errors. * All query cache system variables will be removed. Trying to set them will return errors. * All tests that are for testing query cache will be removed. Some tests use the query cache as a means to other ends (e.g. reducing I/O); we will need to look at these on a case-by-case basis. * All RQG grammars that set SQL_CACHE/SQL_NO_CACHE will have these parts removed. Apart from that, the procedure is quite obvious; we just remove all query cache- related code.
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