Oracle-L: Re: Insert append generating redo

From: Robert Pegram <pegramrg_at_yahoo.com>
Date: Tue, 09 Apr 2002 11:35:42 -0800
Message-ID: <F001.0043FD46.20020409113542@fatcity.com>

Stephane,

I don't understand what you mean when you say you can select on t1 before any commit.

I just tried this on an 8.1.7 database, and there was a signicant reduction in redo. There was only 668 bytes of redo generated vs. 2320 (see below). I think some redo will still be generated as you allocate extents (my tablespace is dictionary managed).

Rob Pegram
Oracle Certified DBA

SQL> create table t as select * from dba_users;

Table created.

SQL> alter table t nologging;

Table altered.

SQL> delete from t;

15 rows deleted.

SQL> commit;

Commit complete.

SQL> select value

   from v$mystat, v$statname
  where v$mystat.statistic# = v$statname.statistic#
    and v$statname.name = 'redo size'

     VALUE

117720

SQL> insert /*+ append */ into t as select * from dba_users;
insert /*+ append */ into t as select * from dba_users

ERROR at line 1:
ORA-00926: missing VALUES keyword

SQL> insert /*+ append */ into t select * from dba_users;

15 rows created.

SQL> commit;

Commit complete.

SQL> select value

   from v$mystat, v$statname
  where v$mystat.statistic# = v$statname.statistic#
    and v$statname.name = 'redo size'

     VALUE

118388

SQL> delete from t;

15 rows deleted.

SQL>
SQL> commit;

Commit complete.

SQL> select value

   from v$mystat, v$statname
  where v$mystat.statistic# = v$statname.statistic#
    and v$statname.name = 'redo size'

     VALUE

123856

SQL> insert into t select * from dba_users;

15 rows created.

SQL> commit;

Commit complete.

SQL> select value

   from v$mystat, v$statname
  where v$mystat.statistic# = v$statname.statistic#
    and v$statname.name = 'redo size'

     VALUE

126176

paquette stephane <stephane_paquette_at_yahoo.com> wrote:
> Hi,
>
> I'm trying the following insert /*+ append */ into
> t1
> as select * from t2;
>
> t1 is created with nologging attribute.
>
> The insert is not using the hint at all.
> I can select on t1 (before any commit) which I
> should
> not be able to do if the append hint was used.
>
> Any ways to get the hing used ?
> (Oracle 817/NT)
>
> TIA
>
> =====
> Stéphane Paquette
> DBA Oracle, consultant entrepôt de données
> Oracle DBA, datawarehouse consultant
> stephane_paquette_at_yahoo.com
>
>

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Author: Robert Pegram
  INET: pegramrg_at_yahoo.com

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Received on Tue Apr 09 2002 - 14:35:42 CDT