How to empty and disable the cache in MariaDB?
Emptying and disabling the Query Cache To empty or clear all results from the query cache, use RESET QUERY CACHE. FLUSH TABLES will have the same effect. Setting either query_cache_type or query_cache_size to 0 will disable the query cache, but to free up the most resources, set both to 0 when you wish to disable caching.
Which is better MaxScale cache or MariaDB query cache?
The cache filter overcomes the limitations of the Query Cache inside MariaDB Server, but it adds a few obstacles of its own. MaxScale cache filter eliminates the mutex issues; and it’s more configurable compared to the MariaDB Server Query Cache. You can specify which tables, databases, columns, etc. are affected with a flexible set of rules.
What happens if a query is not found in the cache?
If the identical query is not found in the cache, the query will be processed normally and then stored, along with its result set, in the query cache. If the query is found in the cache, the results will be pulled from the cache, which is much quicker than processing it normally. Queries are examined in a case-sensitive manner, so :
When to set flags in the cache hash?
Internally a flag (FLAGS_IN_TRANS) is set to 0 when a query was executed outside a transaction, and to 1 when the query was inside a transaction ( BEGIN / COMMIT / ROLLBACK ). This flag is part of the “query cache hash\\
When does a query appear in the cache?
When the query cache is enabled and a new SELECT query is processed, the query cache is examined to see if the query appears in the cache. Queries are considered identical if they use the same database, same protocol version and same default character set.
Is there a way to flush query cache?
FLUSH QUERY CACHE will defragment the query cache without dropping any queries : After this, there will only be one free block : To empty or clear all results from the query cache, use RESET QUERY CACHE. FLUSH TABLES will have the same effect.
How can I limit the size of my query cache?
There are two main ways to limit the size of the query cache. First, the overall size in bytes is determined by the query_cache_size server variable. About 40KB is needed for various query cache structures. The query cache size is allocated in 1024 byte-blocks, thus it should be set to a multiple of 1024.
What is the status of the query cache?
A number of status variables provide information about the query cache. Qcache_inserts contains the number of queries added to the query cache, Qcache_hits contains the number of queries that have made use of the query cache, while Qcache_lowmem_prunes contains the number of queries that were dropped from the cache due to lack of memory.