Details
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Type:
Task
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Status: Open
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Priority:
Minor
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Resolution: Unresolved
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Fix Version/s: None
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Component/s: Query Cache
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Labels:
Description
after MDEV-3932 mysql 5.6 merge
we will have partition lock prune, this is nice, but query cache need information about partition being used in update/delete to invalidade only queries that use the table + partition, not only the table
removing all queries without partition information reduce a lot query cache hits
i send a bug report to mysql at: http://bugs.mysql.com/bug.php?id=69501
to implement this at mysqld too
since we can have more than 8000 partitions, could be nice a query cache map in partition information, like
ALTER TABLE aaa PARTITION ppp QUERY_CACHE_ID=1/SQL_NO_CACHE/NEW/PARTITION(pp1)
1 = an id to group partitions
SQL_NO_CACHE = don't cache this partition (redure memory use and query cache lowmem problem)
NEW = get the last id used and add +1
PARTITION(pp1) = get the same QUERY_CACHE_ID of PARTITION(pp1)
With this we could better remove queries from query cache when one partition or a group of partitions (with same QUERY_CACHE_ID) change, or dont cache some partitions (QUERY_CACHE_ID=SQL_NO_CACHE)
This change qc_info.cc plugin since we have a QUERY_CACHE_TABLE that have all tables used, we should add the PARTITION_QC_ID column to allow a better understand of what partition was used, (maybe set to NULL when table don't have partition)
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