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好的，我有 200 万行。每个都有一个计费日期。我正试图在那个日期之前把它分开。我做了分区。我检查了 /var/lib/mysql 并且文件都在那里，所有文件大小都合适，所以我可以看到某些东西正在工作。但是，当我解释分区选择时，它仍然告诉我它正在使用所有分区。我在建表的方式上做错了吗？查询表？索引？

CREATE TABLE `billing_bil` (
`id_bil` mediumint(9) unsigned NOT NULL AUTO_INCREMENT,
`bill_date_bil` date NOT NULL
PRIMARY KEY (`id`,`bill_date_bil`),
KEY `bill_date_bil` (`bill_date_bil`),
KEY `type_bill_date_bil` (`type_bil`,`bill_date_bil`)
) ENGINE=MyISAM AUTO_INCREMENT=2310168 DEFAULT CHARSET=latin1
/*!50100 PARTITION BY RANGE ( YEAR(bill_date_bil))
(PARTITION p0 VALUES LESS THAN (2008) ENGINE = MyISAM,
PARTITION p1 VALUES LESS THAN (2009) ENGINE = MyISAM,
PARTITION p2 VALUES LESS THAN (2010) ENGINE = MyISAM,
PARTITION p3 VALUES LESS THAN (2011) ENGINE = MyISAM,
PARTITION p4 VALUES LESS THAN (2012) ENGINE = MyISAM,
PARTITION p5 VALUES LESS THAN (2013) ENGINE = MyISAM,
PARTITION p6 VALUES LESS THAN (2014) ENGINE = MyISAM,
PARTITION p7 VALUES LESS THAN MAXVALUE ENGINE = MyISAM) */

EXPLAIN PARTITIONS SELECT SQL_NO_CACHE  id_bil FROM billing_bil WHERE bill_date_bil < '2010'
    id  select_type  table        partitions               type    possible_keys  key      key_len  ref        rows  Extra                   

 1  SIMPLE       billing_bil  p0,p1,p2,p3,p4,p5,p6,p7  index   bill_date_bil  PRIMARY  6        (NULL)  2310167  Using where; Using index

我期待该查询仅使用 p0 和 p1，但它使用了所有这些。

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1 回答 1

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你的分区没问题。您的查询WHERE子句是问题所在。当我EXPLAIN PARTITIONS在 MySQL 5.5 上运行该语句时，有两个警告：

+---------+------+------------------------------------------------------------------+
| Level   | Code | Message                                                          |
+---------+------+------------------------------------------------------------------+
| Warning | 1292 | Incorrect date value: '2010' for column 'bill_date_bil' at row 1 |
| Warning | 1292 | Incorrect date value: '2010' for column 'bill_date_bil' at row 1 |
+---------+------+------------------------------------------------------------------+

如果您将查询更改为使用这样的真实日期，它将使用分区（我没有在我的CREATE TABLE语句中包含您的索引，这就是不使用它们的原因）：

mysql> EXPLAIN PARTITIONS SELECT SQL_NO_CACHE  id_bil FROM billing_bil WHERE bill_date_bil < '2010-01-01';
+----+-------------+-------------+------------+--------+---------------+------+---------+------+------+-------+
| id | select_type | table       | partitions | type   | possible_keys | key  | key_len | ref  | rows | Extra |
+----+-------------+-------------+------------+--------+---------------+------+---------+------+------+-------+
|  1 | SIMPLE      | billing_bil | p0,p1,p2   | system | NULL          | NULL | NULL    | NULL |    1 |       |
+----+-------------+-------------+------------+--------+---------------+------+---------+------+------+-------+

我猜它使用分区p2是因为 MySQL 支持部分日期（2010-00-00小于2010-01-01）：How to deal with "partial" dates (2010-00-00) from MySQL in Django?

于 2011-07-25T23:24:33.330 回答