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Re: custom storage backend rnd_next() implementation and caching questions
On 30.01.15 17:19, Sergei Golubchik wrote:
2. If i am issuing:
SELECT * FROM `/var`;
twice, then the server is not initiating a table scan again on my
backend (most likely results from the first run are stored in some
cache). So if filesystem contents are changed between the two
statements, then it won’t be reflected in the resultset.
Of course if i do a:
SELECT SQL_NO_CACHE * FROM `/var`;
then everything is fine, however i would not like to put the burden on
the user to specify the option to not cache the results.
My question is whether it’s possible to specify in the storage backend
that the results from the tables should not be cached.
Yes. See handler::register_query_cache_table().
If you do not want any results with this engine cached use
table_cache_type() returning HA_CACHE_TBL_NOCACHE .