Mysql Caching

By default there is no caching enabled in MYSQL, to improve performance, add a little memory to the cache to help speed up responses by storing queries.

in mysql type

show variables like 'query_cache_size';

this will show the value of the current cache size, to modify the cache size use ->

SET GLOBAL query_cache_size = 16777216;

That sets the cache to 16mb of each instance of mysql that runs. Don’t over do this value if you are running on a VPS with limited resources.

How do you know if your cache size is right? Check out the Qcaches and look at the results

show status like "qcache%";

+————————-+———-+
| Variable_name           | Value    |
+————————-+———-+
| Qcache_free_blocks      | 42       |
| Qcache_free_memory      | 16431944 |
| Qcache_hits             | 339      |
| Qcache_inserts          | 759      |
| Qcache_lowmem_prunes    | 0        |
| Qcache_not_cached       | 179      |
| Qcache_queries_in_cache | 188      |
| Qcache_total_blocks     | 451      |
+————————-+———-+
The lowmem_prunes is the important value here,  it counts the number of  times the cache had to be free up spaces to cache a new result set.

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