[Oracle]高效的PL/SQL程序设计(四)--批量处理

批量处理一般用在ETL操作, ETL代表提取(extract),转换(transform),装载(load), 是一个数据仓库的词汇!

类似于下面的结构：


for x (select * from...)


loop


Process data;


insert into table values(...);


end loop;

一般情况下, 我们处理大笔的数据插入动作, 有2种做法, 第一种就是一笔笔的循环插入


create table t1 as select * from user_tables where 1=0;


create table t2 as select * from user_tables where 1=0;


create table t3 as select table_name from user_tables where 1=0;


create or replace procedure Nor_Test


as


begin


for x in(select * from user_tables)


loop


insert into t1 values x;


end loop;


end;

第2种方法就是批量处理(insert全部字段)：


create or replace procedure Bulk_Test1(p_array_size in number)


as


type array is table of user_tables%rowtype;


l_data array;


cursor c is select * from user_tables;


begin


open c;


loop


fetch c bulk collect into l_data limit p_array_size;




forall i in 1..l_data.count


insert into t2 values l_data(i);




exit when c%notfound;


end loop;


end;

insert部分字段：


create or replace procedure Bulk_Test2(p_array_size in number)


as


l_tablename dbms_sql.Varchar2_Table;


cursor c is select table_name from user_tables;


begin


open c;


loop


fetch c bulk collect into l_tablename limit p_array_size;




forall i in 1..l_tablename.count


insert into t3 values (l_tablename(i));




exit when c%notfound;


end loop;


end;

在性能方面批量处理有着很大的优势, p_array_size一般默认都是100