| bad performance in import when table created previously [message #73624] |
Sun, 06 June 2004 23:21  |
derys
Messages: 1
Registered: June 2004
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Junior Member |
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Hi, All:
I am facing the following problem of import.
1. Due to the need of re-oragnize the tablespace, i have to create the table/index structure firstly, then import full database, the rollback segment will grow much faster than normal and hit the limit even if i set RBS to 3G with 5 rollback segments which is as big as RBS. My biggest table has 9M rows and total export file has 7G.
2. when i try to use commit=Y, the performance will be very very bad.
Looking forward to ur answer, thanks.
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| Re: bad performance in import when table created previously [message #73665 is a reply to message #73624] |
Tue, 15 June 2004 12:14  |
croca
Messages: 50
Registered: January 2004
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Member |
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what i usually do is
create the new table
insert /*+APPEND*/ INTO NEW_TB SELECT * FROM OLD_TB;
no matter where your old tb is allocated, if it is a remote database works ok (just put @remote_db alias)
This is extremely fast.
And the new_tb can be created as NOLOGGING
and you can also parallelize the select statement if you have more than one cpu just adding the hint:
select /*+ parallel(old_tb,4)*/ * from old_tb;
Best luck.
Planning to use RMAN?, try RMAN VIEWER from
www.otools.com.ar
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