【www.bbyears.com--php与数据库】
在这里简单介绍一下MariaDB的缓存相关参数。
have_query_cache
MariaDB [(none)]> SHOW VARIABLES LIKE "have_query_cache";
+------------------+-------+
| Variable_name | Value |
+------------------+-------+
| have_query_cache | YES |
+------------------+-------+
1 row in set (0.00 sec)
query_cache_limit
MariaDB [(none)]> SHOW VARIABLES LIKE "query_cache_limit";
+-------------------+---------+
| Variable_name | Value |
+-------------------+---------+
| query_cache_limit | 1048576 |
+-------------------+---------+
1 row in set (0.00 sec)
query_cache_min_res_unit
SHOW VARIABLES LIKE "query_cache_min_res_unit";
+--------------------------+-------+
| Variable_name | Value |
+--------------------------+-------+
| query_cache_min_res_unit | 4096 |
+--------------------------+-------+
1 row in set (0.00 sec)
query_cache_size
MariaDB [(none)]> SHOW VARIABLES LIKE "query_cache_size";
+------------------+-------+
| Variable_name | Value |
+------------------+-------+
| query_cache_size | 0 |
+------------------+-------+
1 row in set (0.00 sec)
query_cache_type
MariaDB [(none)]> SHOW VARIABLES LIKE "query_cache_type";
+------------------+-------+
| Variable_name | Value |
+------------------+-------+
| query_cache_type | ON |
+------------------+-------+
1 row in set (0.00 sec)
query_cache_wlock_invalidate
MariaDB [(none)]> SHOW VARIABLES LIKE "query_cache_wlock_invalidate";
+------------------------------+-------+
| Variable_name | Value |
+------------------------------+-------+
| query_cache_wlock_invalidate | OFF |
+------------------------------+-------+
1 row in set (0.00 sec)
确认查询缓存情况
如何确认一个数据库的查询缓存情况，如命中率如何，配置的内存是否妥当？
MariaDB提供了一系列的SHOW STATUS命令来确认当前的查询缓存状态。
MariaDB [(none)]> SHOW STATUS LIKE "Qcache%";
+-------------------------+-------+
| Variable_name | Value |
+-------------------------+-------+
| Qcache_free_blocks | 0 |
| Qcache_free_memory | 0 |
| Qcache_hits | 0 |
| Qcache_inserts | 0 |
| Qcache_lowmem_prunes | 0 |
| Qcache_not_cached | 0 |
| Qcache_queries_in_cache | 0 |
| Qcache_total_blocks | 0 |
+-------------------------+-------+
8 rows in set (0.00 sec)
清除查询缓存
MariaDB [(none)]> RESET QUERY CACHE;
Query OK, 0 rows affected (0.00 sec)