数据处理时应注意的一点东西

lxd_sh

1.so sometime ,when operate some large object ,constantly first create the indexes,and later create the corelative constraints

2.some time migrant a large table from a database to another,can not export corelative indexes,because
when import data, at the same time generate index data ,the efficiency is very low
the clause include
indexes ='N';

if you dont want to generate the index because of the set of primary key ,when you exp ,you should not  exp
the constraints the clause is
constraints ='N'
       
       
3.when set initrans and maxtrans storage parameters for
index ,you should  give  large values to initrans and
maxtrans when the index constantly would be accessed by many ---users cocurrently.

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