Is it because, truncate has to reset the HWM?
GovindanK
- gmei <gmei_at_incyte.com> wrote: > Hi:
> Oracle 8173 on Sun Solaris 2.8.
> I am running a program that creates and drops tables
> repeatedly in a schema.
> The table dropping part looks like this:
>
> drop table ypd.t1 cascade constraints;
> drop table ypd.t2 cascade constraints;
> drop table ypd.t3 cascade constraints;
> drop table ypd.t4 cascade constraints;
> ....
>
> I thought I might be able to use "truncate table ..." and
> then "drop table
> ..." to make this process a bit faster. However the tests
> I did today showed
> otherwise:
>
> SQL> select bytes from dba_segments where
> segment_name='SEQUENCE';
>
> BYTES
> ----------
> 1949810688
>
> SQL> create table ypd_owner.SEQUENCE1
> 2 tablespace ypd nologging as select * from
> mt.SEQUENCE;
>
> Table created.
>
> Elapsed: 00:04:272.50
> SQL> drop table ypd_owner.SEQUENCE1;
>
> Table dropped.
>
> Elapsed: 00:00:05.19
> SQL> create table ypd_owner.SEQUENCE1
> 2 tablespace ypd nologging as select * from
> mt.SEQUENCE;
>
> Table created.
>
> Elapsed: 00:04:275.85
> SQL> truncate table ypd_owner.SEQUENCE1;
>
> Table truncated.
>
> Elapsed: 00:00:06.99
> SQL> drop table ypd_owner.SEQUENCE1;
>
> Table dropped.
>
> Elapsed: 00:00:00.70
>
> -----------
> Tablspace ypd is LMT. Similar test on smaller table
> showed the same result
> "drop table ..." is faster than "truncate table ...". Any
> explanation?
> TIA.
>
> Guang
>
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> Author: gmei
> INET: gmei_at_incyte.com
>
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Received on Mon Mar 10 2003 - 16:21:20 CST