mysql - 由于某种原因，ProxySQL 查询缓存并不总是遵守查询规则

Question

我使用 ProxySQL (2.0.17) 缓存所有发送到 MySQL 的 SELECT 查询。该mysql_query_rules表如下所示：

+---------+--------+----------+------------+--------+-------------+------------+------------+--------+------------------------------+---------------+----------------------+--------------+---------+-----------------+-----------------------+-----------+--------------------+---------------+-----------+---------+---------+-------+-------------------+----------------+------------------+-----------+--------+-------------+-----------+---------------------+-----+-------+---------+
| rule_id | active | username | schemaname | flagIN | client_addr | proxy_addr | proxy_port | digest | match_digest                 | match_pattern | negate_match_pattern | re_modifiers | flagOUT | replace_pattern | destination_hostgroup | cache_ttl | cache_empty_result | cache_timeout | reconnect | timeout | retries | delay | next_query_flagIN | mirror_flagOUT | mirror_hostgroup | error_msg | OK_msg | sticky_conn | multiplex | gtid_from_hostgroup | log | apply | comment |
+---------+--------+----------+------------+--------+-------------+------------+------------+--------+------------------------------+---------------+----------------------+--------------+---------+-----------------+-----------------------+-----------+--------------------+---------------+-----------+---------+---------+-------+-------------------+----------------+------------------+-----------+--------+-------------+-----------+---------------------+-----+-------+---------+
| 1       | 1      | NULL     | NULL       | 0      | NULL        | NULL       | NULL       | NULL   | ^[(]?SELECT (?!SQL_NO_CACHE) | NULL          | 0                    | CASELESS     | NULL    | NULL            | NULL                  | 300000    | NULL               | NULL          | NULL      | NULL    | NULL    | NULL  | NULL              | NULL           | NULL             | NULL      | NULL   | NULL        | NULL      | NULL                | NULL | 1     | NULL    |
+---------+--------+----------+------------+--------+-------------+------------+------------+--------+------------------------------+---------------+----------------------+--------------+---------+-----------------+-----------------------+-----------+--------------------+---------------+-----------+---------+---------+-------+-------------------+----------------+------------------+-----------+--------+-------------+-----------+---------------------+-----+-------+---------+

一个简单的规则（我也试过^SELECT .*）和 300 秒等待缓存的查询被清除。

出于某种原因，每个要缓存的查询仍有 5% 被发送到后端。例如，这是最流行的查询：

+-----------+------------+----------+----------------+--------------------+--------------------------+------------+------------+------------+-------------+----------+----------+-------------------+---------------+
| hostgroup | schemaname | username | client_address | digest             | digest_text              | count_star | first_seen | last_seen  | sum_time    | min_time | max_time | sum_rows_affected | sum_rows_sent |
+-----------+------------+----------+----------------+--------------------+--------------------------+------------+------------+------------+-------------+----------+----------+-------------------+---------------+
| 2         | ------     | ----     |                | 0xFB50749BCFE0DA3C | SELECT * FROM `language` | 12839      | 1621445210 | 1621455115 | 45069293213 | 31321    | 82235606 | 0                 | 56960         |
| -1        | ------     | ----     |                | 0xFB50749BCFE0DA3C | SELECT * FROM `language` | 326243     | 1621445210 | 1621455116 | 0           | 0        | 0        | 0                 | 0             |
+-----------+------------+----------+----------------+--------------------+--------------------------+------------+------------+------------+-------------+----------+----------+-------------------+---------------+

我无法理解这种特殊性。每当我更新stats_mysql_query_digest时，count_staron hostgroup 2(backend) 都会增加，而无需等待 300 秒来清除查询。

查询缓存大小设置为 512 Mb。在高峰期，它占用大约 100 Mb。

帮助？..

Answer 1

加速到5120 mysql-query_cache_size_MBMB（这当然是荒谬的）似乎在一定程度上解决了这个问题。该查询的后端请求频率下降了 10 倍（感谢 ProxySQL 的查询日志，您可以只记录一个查询并对其进行分析）。该cache_ttl值仍远未得到尊重，但我想这种解决方法在这一点上总比没有好。