求助：MySQL如何按天分區(qū)

所謂按天，不過是日期精確到天而已。

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錯誤的按日期分區(qū)例子

最直觀的方法，就是直接用年月日這種日期格式來進(jìn)行常規(guī)的分區(qū)：

mysql??create?table?rms?(d?date)??

-??partition?by?range?(d)??

-?(partition?p0?values?less?than?('1995-01-01'),??

-??partition?p1?VALUES?LESS?THAN?('2010-01-01'));

上面的例子中，就是直接用"Y-m-d"的格式來對一個table進(jìn)行分區(qū)，可惜想當(dāng)然往往不能奏效，會得到一個錯誤信息:

ERROR 1064 (42000): VALUES value must be of same type as partition function near '),

partition p1 VALUES LESS THAN ('2010-01-01'))' at line 3

上述分區(qū)方式?jīng)]有成功，而且明顯的不經(jīng)濟(jì)，老練的DBA會用整型數(shù)值來進(jìn)行分區(qū)：

mysql?CREATE?TABLE?part_date1??

-??????(??c1?int?default?NULL,??

-??c2?varchar(30)?default?NULL,??

-??c3?date?default?NULL)?engine=myisam??

-??????partition?by?range?(cast(date_format(c3,'%Y%m%d')?as?signed))??

-?(PARTITION?p0?VALUES?LESS?THAN?(19950101),??

-?PARTITION?p1?VALUES?LESS?THAN?(19960101)?,??

-?PARTITION?p2?VALUES?LESS?THAN?(19970101)?,??

-?PARTITION?p3?VALUES?LESS?THAN?(19980101)?,??

-?PARTITION?p4?VALUES?LESS?THAN?(19990101)?,??

-?PARTITION?p5?VALUES?LESS?THAN?(20000101)?,??

-?PARTITION?p6?VALUES?LESS?THAN?(20010101)?,??

-?PARTITION?p7?VALUES?LESS?THAN?(20020101)?,??

-?PARTITION?p8?VALUES?LESS?THAN?(20030101)?,??

-?PARTITION?p9?VALUES?LESS?THAN?(20040101)?,??

-?PARTITION?p10?VALUES?LESS?THAN?(20100101),??

-?PARTITION?p11?VALUES?LESS?THAN?MAXVALUE?);

Query OK, 0 rows affected (0.01 sec)

搞定？接著往下分析

mysql?explain?partitions??

-?select?count(*)?from?part_date1?where??

-??????c3?'1995-01-01'?and?c3?'1995-12-31'\G??

***************************?1.?row?***************************??

id:?1??

select_type:?SIMPLE??

table:?part_date1??

partitions:?p0,p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11??

type:?ALL??

possible_keys:?NULL??

key:?NULL??

key_len:?NULL??

ref:?NULL??

rows:?8100000??

Extra:?Using?where??

1?row?in?set?(0.00?sec)

萬惡的mysql居然對上面的sql使用全表掃描，而不是按照我們的日期分區(qū)分塊查詢。原文中解釋到MYSQL的優(yōu)化器并不認(rèn)這種日期形式的分區(qū)，花了大量的篇幅來引誘俺走上歧路，過分。

正確的日期分區(qū)例子

mysql優(yōu)化器支持以下兩種內(nèi)置的日期函數(shù)進(jìn)行分區(qū)：

TO_DAYS()

YEAR()

看個例子：

mysql?CREATE?TABLE?part_date3??

-??????(??c1?int?default?NULL,??

-??c2?varchar(30)?default?NULL,??

-??c3?date?default?NULL)?engine=myisam??

-??????partition?by?range?(to_days(c3))??

-?(PARTITION?p0?VALUES?LESS?THAN?(to_days('1995-01-01')),??

-?PARTITION?p1?VALUES?LESS?THAN?(to_days('1996-01-01'))?,??

-?PARTITION?p2?VALUES?LESS?THAN?(to_days('1997-01-01'))?,??

-?PARTITION?p3?VALUES?LESS?THAN?(to_days('1998-01-01'))?,??

-?PARTITION?p4?VALUES?LESS?THAN?(to_days('1999-01-01'))?,??

-?PARTITION?p5?VALUES?LESS?THAN?(to_days('2000-01-01'))?,??

-?PARTITION?p6?VALUES?LESS?THAN?(to_days('2001-01-01'))?,??

-?PARTITION?p7?VALUES?LESS?THAN?(to_days('2002-01-01'))?,??

-?PARTITION?p8?VALUES?LESS?THAN?(to_days('2003-01-01'))?,??

-?PARTITION?p9?VALUES?LESS?THAN?(to_days('2004-01-01'))?,??

-?PARTITION?p10?VALUES?LESS?THAN?(to_days('2010-01-01')),??

-?PARTITION?p11?VALUES?LESS?THAN?MAXVALUE?);

Query OK, 0 rows affected (0.00 sec)

以to_days()函數(shù)分區(qū)成功，我們分析一下看看：

mysql?explain?partitions??

-?select?count(*)?from?part_date3?where??

-??????c3?date?'1995-01-01'?and?c3?date?'1995-12-31'\G??

***************************?1.?row?***************************??

id:?1??

select_type:?SIMPLE??

table:?part_date3??

partitions:?p1??

type:?ALL??

possible_keys:?NULL??

key:?NULL??

key_len:?NULL??

ref:?NULL??

rows:?808431??

Extra:?Using?where??

1?row?in?set?(0.00?sec)

可以看到，mysql優(yōu)化器這次不負(fù)眾望，僅僅在p1分區(qū)進(jìn)行查詢。在這種情況下查詢，真的能夠帶來提升查詢效率么？下面分別對這次建立的part_date3和之前分區(qū)失敗的part_date1做一個查詢對比：

mysql?select?count(*)?from?part_date3?where??

-??????c3?date?'1995-01-01'?and?c3?date?'1995-12-31';??

+----------+??

|?count(*)?|??

+----------+??

|???805114?|??

+----------+??

1?row?in?set?(4.11?sec)??

mysql?select?count(*)?from?part_date1?where??

-??????c3?date?'1995-01-01'?and?c3?date?'1995-12-31';??

+----------+??

|?count(*)?|??

+----------+??

|???805114?|??

+----------+??

1?row?in?set?(40.33?sec)

可以看到，分區(qū)正確的話query花費時間為4秒，而分區(qū)錯誤則花費時間40秒（相當(dāng)于沒有分區(qū)），效率有90％的提升！所以我們千萬要正確的使用分區(qū)功能，分區(qū)后務(wù)必用explain驗證，這樣才能獲得真正的性能提升。

注意：

在mysql5.1中建立分區(qū)表的語句中，只能包含下列函數(shù)：

ABS()

CEILING()?and?FLOOR()?（在使用這2個函數(shù)的建立分區(qū)表的前提是使用函數(shù)的分區(qū)鍵是INT類型），例如

mysql?CREATE?TABLE?t?(c?FLOAT)?PARTITION?BY?LIST(?FLOOR(c)?)(?-?PARTITION?p0?VALUES?IN?(1,3,5),?-?PARTITION?p1?VALUES?IN?(2,4,6)?-?);;?ERROR?1491?(HY000):?The?PARTITION?function?returns?the?wrong?type???mysql?CREATE?TABLE?t?(c?int)?PARTITION?BY?LIST(?FLOOR(c)?)(?-?PARTITION?p0?VALUES?IN?(1,3,5),?-?PARTITION?p1?VALUES?IN?(2,4,6)?-?);?Query?OK,?0?rows?affected?(0.01?sec)??

DAY()??

DAYOFMONTH()??

DAYOFWEEK()??

DAYOFYEAR()??

DATEDIFF()??

EXTRACT()??

HOUR()??

MICROSECOND()??

MINUTE()??

MOD()??

MONTH()??

QUARTER()??

SECOND()??

TIME_TO_SEC()??

TO_DAYS()??

WEEKDAY()??

YEAR()??

YEARWEEK()

Mysql按時間進(jìn)行表分區(qū)

以下是創(chuàng)建一張測試表TEST并且按照時間CREATE_TIME創(chuàng)建RANGE分區(qū)，并使用ID創(chuàng)建hash分區(qū)，組成復(fù)合分區(qū)。

CREATE TABLE TEST (

CREATE_TIME DATETIME DEFAULT NULL, ID BIGINT(15) DEFAULT NULL

) ENGINE=INNODB DEFAULT CHARSET=utf8

PARTITION BY RANGE(TO_DAYS(CREATE_TIME)) PARTITIONS 7 SUBPARTITION BY HASH(ID) SUBPARTITIONS 16

(PARTITION P1710 VALUES LESS THAN (TO_DAYS ('2017-10-01'))

(SUBPARTITION P1710sp0 ,SUBPARTITION P1710sp1 ,

SUBPARTITION P1710sp2 ,SUBPARTITION P1710sp3 ,

SUBPARTITION P1710sp4 ,SUBPARTITION P1710sp5 ,

SUBPARTITION P1710sp6 ,SUBPARTITION P1710sp7 ,

SUBPARTITION P1710sp8 ,SUBPARTITION P1710sp9 ,

SUBPARTITION P1710sp10 ,SUBPARTITION P1710sp11 ,

SUBPARTITION P1710sp12 ,SUBPARTITION P1710sp13 ,

SUBPARTITION P1710sp14 ,SUBPARTITION P1710sp15 ),

PARTITION P1711 VALUES LESS THAN (TO_DAYS ('2017-11-01'))

(SUBPARTITION P1711sp0 ,SUBPARTITION P1711sp1 ,

SUBPARTITION P1711sp2 , SUBPARTITION P1711sp3 ,

SUBPARTITION P1711sp4 , SUBPARTITION P1711sp5 ,

SUBPARTITION P1711sp6 , SUBPARTITION P1711sp7 ,

SUBPARTITION P1711sp8 , SUBPARTITION P1711sp9 ,

SUBPARTITION P1711sp10 , SUBPARTITION P1711sp11 ,

SUBPARTITION P1711sp12 , SUBPARTITION P1711sp13 ,

SUBPARTITION P1711sp14 , SUBPARTITION P1711sp15 ),

mysql 怎么按照時間做表分區(qū)

用mysql的表分區(qū)功能（邏輯上還是一個表，對程序來說是透明的），通過分區(qū)函數(shù)可實現(xiàn)自動分表。如果想實現(xiàn)根據(jù)數(shù)據(jù)每月或每周動態(tài)的再分區(qū)，可以寫一個存儲過程實現(xiàn)分區(qū)調(diào)整邏輯，最后寫一個mysql event（自動化作業(yè)）按周期調(diào)用這個存儲過程就行了。