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原理：數(shù)據(jù)表的hash分區(qū)字段與分析函數(shù)中的partition by 字段一致的時(shí)候，每個(gè)分區(qū)上的數(shù)據(jù)可以單獨(dú)進(jìn)行運(yùn)算，互不干涉。所以可以很快的提高Oracle分析函數(shù)的運(yùn)行效率。具體測試步驟如下：
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***步：創(chuàng)建一個(gè)分區(qū)表和普通表，表結(jié)構(gòu)與DBA_OBJECTS一致：
- create table t_partition_hash(
- object_name varchar2(128),
- subobject_name varchar2(30),
- object_id number,
- data_object_id number,
- object_type varchar2(19),
- created date,
- last_ddl_time date,
- timestamp varchar2(19),
- status varchar2(7),
- temporary varchar2(1),
- generated varchar2(1),
- secondary varchar2(1)
- )
- partition by hash(object_type)(
- partition t_hash_p1 tablespace USERS,
- partition t_hash_p2 tablespace USERS,
- partition t_hash_p3 tablespace USERS,
- partition t_hash_p4 tablespace USERS,
- partition t_hash_p5 tablespace USERS,
- partition t_hash_p6 tablespace USERS,
- partition t_hash_p7 tablespace USERS,
- partition t_hash_p8 tablespace USERS
- );
- create table t_big_hash(
- object_name varchar2(128),
- subobject_name varchar2(30),
- object_id number,
- data_object_id number,
- object_type varchar2(19),
- created date,
- last_ddl_time date,
- timestamp varchar2(19),
- status varchar2(7),
- temporary varchar2(1),
- generated varchar2(1),
- secondary varchar2(1)
- );
#p#
第二步：準(zhǔn)備數(shù)據(jù)，從dba_object中把數(shù)據(jù)插入到兩個(gè)表?？偣膊迦霐?shù)據(jù)1610880。
- insert into t_partition_hash select * from dba_objects;
- insert into t_partition_hash select * from dba_objects;
第三步：本采用RANK函數(shù)對(duì)兩個(gè)表進(jìn)行查詢。
- begin
- insert into t_rank
- select object_id,
- rank() over (partition by object_type order by object_id) r_object_id,
- rank() over (partition by object_type order by subobject_name) r_subobject_name ,
- rank() over (partition by object_type order by created) r_created,
- rank() over (partition by object_type order by last_ddl_time) r_last_ddl_time ,
- rank() over (partition by object_type order by status) r_object_type
- from t_partition_hash;
- end;
使用hash分區(qū)表總共執(zhí)行5次的運(yùn)行時(shí)間分別為：46.156s,33.39s,40.516s 34.875s 38.938s.
- begin
- insert into t_rank
- select object_id,
- rank() over (partition by object_type order by object_id) r_object_id,
- rank() over (partition by object_type order by subobject_name) r_subobject_name ,
- rank() over (partition by object_type order by created) r_created,
- rank() over (partition by object_type order by last_ddl_time) r_last_ddl_time ,
- rank() over (partition by object_type order by status) r_object_type
- from t_big_table;
- end;
使用非分區(qū)表執(zhí)行5次的執(zhí)行時(shí)間分別為：141.954s，89.656s，77.906s，98.5s，75.906s.
由此可見采用有效的HASH分區(qū)表可以有效提升Oracle分析函數(shù)中的執(zhí)行效率。我相信隨著數(shù)據(jù)量的增加，將會(huì)有更明顯的效果，回頭再測試一個(gè)項(xiàng)目中遇到的類似問題。
善用Oracle表空間設(shè)計(jì)提升數(shù)據(jù)庫性能
優(yōu)化數(shù)據(jù)庫大幅度提高Oracle分析函數(shù)的性能
Oracle設(shè)置系統(tǒng)參數(shù)進(jìn)行性能優(yōu)化
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- Oracle SQL的優(yōu)化規(guī)則解析
網(wǎng)站欄目：如何使用Hash分區(qū)優(yōu)化Oracle分析函數(shù)
文章源于：http://m.5511xx.com/article/cddcgop.html
