Posted by Vadim |

Recently we were puzzled by question how query_cache works with column level privileges. The question was appeared as we discovered function query_cache_send_result_to_client is called before real parsing of query, so at the moment of execution the query_cache is not able to know which columns are accessed.
Looking into source code I found out that in the case when table has column level privileges – function query_cache_send_result_to_client just stopped and returns to usual execution. So initial assumtion was that query against table with defined column privilege is just not cached, though it is not reflected in documentation.
It was worth to test it experimentally and the reality turned out more interesting.
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