我注意到运行时得到的表总计:
SELECT TABLE_NAME, TABLE_ROWS FROM `information_schema`.`tables` WHERE `table_schema` = 'my_database';
导致总计不正确。我还读,这样做:
analyze table 'my_table';
将正确更新信息。但似乎并非如此。因此,要设置基线:
mysql> select count(*) from my_table;
+----------+
| count(*) |
+----------+
| 61782 |
+----------+
1 row in set (0.01 sec)
接下来,统计信息将显示:
mysql> SELECT TABLE_NAME, TABLE_ROWS FROM `information_schema`.`tables` WHERE `table_schema` = 'my_database' AND TABLE_NAME = 'my_table';
+--------------------+------------+
| TABLE_NAME | TABLE_ROWS |
+--------------------+------------+
| my_table | 58378 |
+--------------------+------------+
1 row in set (0.00 sec)
显然,这是不对的,所以我进行分析并再次检查:
mysql> analyze table my_table;
+------------------------------+---------+----------+----------+
| Table | Op | Msg_type | Msg_text |
+------------------------------+---------+----------+----------+
| my_database.my_table | analyze | status | OK |
+------------------------------+---------+----------+----------+
1 row in set (0.02 sec)
mysql> SELECT TABLE_NAME, TABLE_ROWS FROM `information_schema`.`tables` WHERE `table_schema` = 'my_database' AND TABLE_NAME = 'my_table';
+--------------------+------------+
| TABLE_NAME | TABLE_ROWS |
+--------------------+------------+
| my_table | 56439 |
+--------------------+------------+
1 row in set (0.00 sec)
好的,它变了,但还是不对。所以我做了好多次:
mysql> analyze table my_table;
+------------------------------+---------+----------+----------+
| Table | Op | Msg_type | Msg_text |
+------------------------------+---------+----------+----------+
| my_database.my_table | analyze | status | OK |
+------------------------------+---------+----------+----------+
1 row in set (0.02 sec)
mysql> SELECT TABLE_NAME, TABLE_ROWS FROM `information_schema`.`tables` WHERE `table_schema` = 'my_database' AND TABLE_NAME = 'my_table';
+--------------------+------------+
| TABLE_NAME | TABLE_ROWS |
+--------------------+------------+
| my_table | 58766 |
+--------------------+------------+
1 row in set (0.00 sec)
mysql> analyze table my_table;
+------------------------------+---------+----------+----------+
| Table | Op | Msg_type | Msg_text |
+------------------------------+---------+----------+----------+
| my_database.my_table | analyze | status | OK |
+------------------------------+---------+----------+----------+
1 row in set (0.02 sec)
mysql> SELECT TABLE_NAME, TABLE_ROWS FROM `information_schema`.`tables` WHERE `table_schema` = 'my_database' AND TABLE_NAME = 'my_table';
+--------------------+------------+
| TABLE_NAME | TABLE_ROWS |
+--------------------+------------+
| my_table | 65749 |
+--------------------+------------+
1 row in set (0.00 sec)
mysql> analyze table my_table;
+------------------------------+---------+----------+----------+
| Table | Op | Msg_type | Msg_text |
+------------------------------+---------+----------+----------+
| my_database.my_table | analyze | status | OK |
+------------------------------+---------+----------+----------+
1 row in set (0.02 sec)
mysql> SELECT TABLE_NAME, TABLE_ROWS FROM `information_schema`.`tables` WHERE `table_schema` = 'my_database' AND TABLE_NAME = 'my_table';
+--------------------+------------+
| TABLE_NAME | TABLE_ROWS |
+--------------------+------------+
| my_table | 61870 |
+--------------------+------------+
1 row in set (0.00 sec)
,正如您所看到的,我从来没有得到相同的数字,它们都不是实际的行数。我的问题是:这是一个指标,我有我的数据库有问题(它在做它的所有表)或者这只是在MySQL中的错误
我的环境的详细信息:
服务器版本:5.6.43 MySQL社区服务器(GPL) 所有表都是INNODB,字符集是utf8
答案 0 :(得分:2)
对于InnoDB,table_rows
统计信息是估计,而不是确切的计数。该值不能保证准确的行计数。
不,这不是MySQL中的错误。 InnoDB统计信息没有错。行为记录在《 MySQL参考手册》中。
参考文献:
https://dev.mysql.com/doc/refman/5.6/en/index-statistics.html
https://dev.mysql.com/doc/refman/5.6/en/innodb-persistent-stats.html