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    下面就筆者工作中遇到的時(shí)間問(wèn)題,模擬一下情況對(duì)大家進(jìn)行介紹.
    工作中仍然是海量數(shù)據(jù)出現(xiàn)的情況.每年大概會(huì)有幾億條記錄.而且數(shù)據(jù)的時(shí)效性比較強(qiáng).但歷史數(shù)據(jù)仍然要求保留.這個(gè)時(shí)候經(jīng)過(guò)分析和研究,最終決定通過(guò)時(shí)間字段進(jìn)行分區(qū).下面是分區(qū)表的創(chuàng)建代碼.讀者門在插入了不同年份時(shí)間段以后，可以時(shí)間字段為條件進(jìn)行查詢，可以看到數(shù)據(jù)庫(kù)掃描過(guò)的區(qū)段.

CREATE TABLE part_data(c1 int default NULL,c2 varchar(30) default NULL,c3 date default NULL)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 );

分區(qū)查詢,可以查看掃描過(guò)的區(qū)段.當(dāng)然要加上where子句,以c3時(shí)間為條件進(jìn)行檢索.若不使用時(shí)間字段，分區(qū)將失去作用.