Re: big MLOG$

From: Xuequn Xu <xux_at_informa.bio.caltech.edu>
Date: Mon, 27 Sep 2004 23:37:57 +0000 (UTC)
Message-ID: <cja88l$614$1@naig.caltech.edu>

Have you checked the number of rows in those 6GB mlog$ tables? Did you realize that the number of rows maybe did not really add up to 6GB, no matter how big each row piece could be? In that case, much of the 6GB is not occupied by real data, and you can safely get rid of much of the "fat" by moving the mlog$ tables:

alter table mlog$some_table move;

optionally specify a new tablespace. After the move, check the bytes in dba_segments for those mlog$. I bet they will be much much smaller than 6GB. Quite often huge mlog$ are result of the snapshots not been refreshed for a long time, and that really pushed the segment size up. The extra space allocated to those mlog$ will not be reclaimed by subsequent succesful refresh, but a "alter table ... move" can.

zeb (spam_at_nowhere.com) wrote:
: Hi,

: I have tables in replication ( read-only snapshot )
: ( datawarehouse, update during the night )
: for somes tables the table MLOG$ is very
: big ( more than 6 GB ) .

: Can I delete rows for the MLOG$ tables ?
: With what criterion ?
: whithout risk for my replication ?

: Thanks for your help ...

: Oracle 8.1.7
: AIX 4.3.3
Received on Mon Sep 27 2004 - 18:37:57 CDT