Original post: http://anothermysqldba.blogspot.com/2013/05/mysql-count-and-select-from-partition.html
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MySQLフォーラムã¯ã€ãƒ‘ーティションã”ã¨ã«è¡Œæ•°ã‚’カウントã™ã‚‹æ–¹æ³•ã«ã¤ã„ã¦ã®è³ªå•ãŒã‚ã£ãŸã€‚
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- http://dev.mysql.com/doc/refman/5.6/en/partitioning.html
- http://dev.mysql.com/tech-resources/articles/mysql_55_partitioning.html
> CREATE TABLE t2
-> (
-> dt DATE
-> )
-> PARTITION BY RANGE (TO_DAYS(dt))
-> (
-> PARTITION p01 VALUES LESS THAN (TO_DAYS('2007-01-01')),
-> PARTITION p02 VALUES LESS THAN (TO_DAYS('2008-01-01')),
-> PARTITION p03 VALUES LESS THAN (TO_DAYS('2009-01-01')),
-> PARTITION p04 VALUES LESS THAN (MAXVALUE));
> desc t2;
+-------+------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+------+------+-----+---------+-------+
| dt | date | YES | | NULL | |
+-------+------+------+-----+---------+-------+ INSERT INTO t2 VALUES ('2007-02-02'),('2008-02-02'),('2009-02-02'),(CURDATE());Query OK, 4 rows affected (0.04 sec)
[OK]ã‚’ã€ä»Šç§ãŸã¡ã¯ã€ãƒ‘ーティションã‹ã‚‰é¸æŠžã™ã‚‹ã ã‘ã§ãªãã€ãã“ã‹ã‚‰æ•°ãˆã‚‹ã“ã¨ãŒã§ãã‚‹..
> select count(*) from t2;
+----------+
| count(*) |
+----------+
| 4 |
+----------+ > explain partitions select count(*) from t2 \G*************************** 1. row ***************************id: 1select_type: SIMPLEtable: t2partitions: p01,p02,p03,p04type: ALLpossible_keys: NULLkey: NULLkey_len: NULLref: NULLrows: 5Extra: NULL> SELECT * t2ã®ãƒ‘ーティションã‹ã‚‰ï¼ˆP02）;
+ ------------ +
| DT |
+ ------------ +
| 2007-02-02 |
+ ------------ +
> SELECT * t2ã®ãƒ‘ーティションã‹ã‚‰ï¼ˆP04）;
+ ------------ +
| DT |
+ ------------ +
| 2009-02-02 |
| 2013年5月15日|
+ ------------ +
> SELECT * t2ã®ãƒ‘ーティションã‹ã‚‰ï¼ˆP02ã€P04）;
+ ------------ +
| DT |
+ ------------ +
| 2007-02-02 |
| 2009-02-02 |
| 2013年5月15日|
+ ------------ +
T2 PARTITION（P04）ã‹ã‚‰> SELECT COUNT（*）;
+ ---------- +
| COUNT（*）|
+ ---------- +
| 2 |
+ ---------- +
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