在 Oracle 中插入一百万行的最快方法

问题描述

对于以下过程，我如何以最佳方式在 Oracle 中插入超过一百万行?如果我将 FOR 循环增加到一百万行，它就会挂起.

How can I insert more than a million rows in Oracle in optimal way for the following procdeure? It hangs if I increase FOR loop to a million rows.

create or replace procedure inst_prc1 as
   xssn number;
   xcount number;
   l_start Number;
   l_end Number;
   cursor c1 is select max(ssn)S1 from dtr_debtors1;

Begin
  l_start := DBMS_UTILITY.GET_TIME;
  FOR I IN 1..10000 LOOP
    For C1_REC IN C1 Loop
      insert into dtr_debtors1(SSN) values (C1_REC.S1+1);
    End loop;
  END LOOP;
  commit;
  l_end := DBMS_UTILITY.GET_TIME;
  DBMS_OUTPUT.PUT_LINE('The Procedure  Start Time is '||l_start);
  DBMS_OUTPUT.PUT_LINE('The Procedure End Time is '||l_end); 
End inst_prc1;

推荐答案

您的方法将导致内存问题.最快的方法是[在大卫的评论后编辑查询以处理空场景]:

Your approach will lead to memory issues. Fastest way will be this [Query edited after David's comment to take care of null scenario] :

insert into dtr_debtors1(SSN)
select a.S1+level
   from dual,(select nvl(max(ssn),0) S1 from dtr_debtors1) a
connect by level <= 10000 

选择插入是最快的方法，因为所有内容都保留在 RAM 中.如果此查询滑入全局临时区域，则它可能会变慢，但这需要 DB 调整.我认为没有比这更快的了.

A select insert is the fastest approach as everything stays in RAM. This query can become slow if it slips into Global temp area but then that needs DB tuning . I don't think there can be anything faster than this.

关于查询内存使用的更多细节:

Few more details on memory use by Query:

每个查询都有自己的 PGA [程序全局区域]，它基本上是每个查询可用的 RAM.如果这个区域不足以返回查询结果，那么 SQL 引擎开始使用 Golabl 临时表空间，就像硬盘一样，查询开始变慢.如果查询需要的数据太大，甚至临时区域都不够用，那么你就会出现表空间错误.

Each query will have its own PGA [Program global area] which is basically RAM available to each query. If this this area is not sufficient to return query results then SQL engine starts using Golabl temp tablespace which is like hard disk and query starts becoming slow. If data needed by query is so huge that even temp area is not sufficient then you will tablespace error.

所以总是设计查询，使其留在 PGA 中，否则它是一个危险信号.

So always design query so that it stays in PGA else its a Red flag.

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