oraclesql语句并行,SQL中并行操作

oraclesql语句并⾏,SQL中并⾏操作

--并⾏查询

何家劲的老婆是谁select /*+parallel(t 4)*/ count(*) from user_tables t;

select /*+parallel(t 4)*/ count(*) from t where object_name in(select /*+parallel(t1 4)*/ object_name from t1);

大型单机游戏--⼀个并⾏查询能够执⾏，需要满⾜下⾯其中⼀个：

a)sql语句中有hint提⽰，⽐如parallel或者parallel_index；

b)sql语句中引⽤的对象被设置了并⾏属性；

c)多表关联中⾄少有⼀个表执⾏全表扫描(full table scan)或者跨越分区的index range scan

d)在会话中执⾏：alter session force parallel query parallel 4;

--并⾏ddl操作：

create table t parallel 4 as select * from dba_objects;

alter table t move partition p1 parallel 4;

罗志祥请等我回来alter table t split partition p1 at(5000) into (partition p1,partition p2) parallel 4;

alter table t coalesce partition parallel 4;

create index t_ind on t(id) parallel 4;

alter index t_ind rebuild parallel 4;

alter index t_ind rebuild partition p1 parallel 4;

危险化学品分类alter index t_ind split partition p1 at(5000) into (partition p11,partition p12) parallel 4;

--并⾏DML操作：

DML操作使⽤并⾏，必须显⽰地在会话⾥执⾏：

alter session enable parallel dml;

重庆中考时间2022年具体时间delete /*+ parallel(t 2)*/ from t;

update /*+ parallel(t 2)*/ t set name=name||'dcs';

merge /*+parallel(t 2)*/ into t using t1 on (t.id=t1.id) when matched then update set t.name=t1.name;

insert /*+parallel(t 4)*/ into t select /*+parallel(t1 4)*/ * from t1;

水利科学与工程

insert into t select /*+parallel(t1 4)*/ * from t1;

insert /*+parallel(t 4)*/ into t select * from t1;

insert /*+ append parallel(t,2)*/ into t select * from t;

--sql*loader和parallel：

--如果使⽤sqlloader的并⾏直接加载选项，并且表上有索引，将导致加载失败，可以调整参数：skip_index_maintenance=true，先把数据插⼊，在rebuild索引。

sqlldr userid=test/oracle l direct=true parallel=true skip_index_maintenance=true ;

alter index t_ind rebuild parallel 4;