Purging OLD data from oracle database
Posted on 2011-02-18
We have a huge OLTP database with oracle 10g. It has data from year 2000 and it is causing performance issues so I’m writing a purge process to clean old data from database. We can’t afford outage to this task so I had written PLSQL code to delete the OLD data. There are 13 tables need to be purged and having parent and child relationship. This is how I have written the code.
Step1: go and grab one chunk (3000) profiles from parent table and load into a one temp table.
Step 2: delete these profiles from child tables. At the end, we are deleting from parent table.
Step 3: commit the data
Step 4: repeat steps 1, 2 and 3 until there are no profile matches deletion criteria.
Here is sample code I have.
Insert into temp (tid)
Select p.id from parent p where date<=cutoff_date and rownum<=3000;
Exit when sql%rowcount=0;
Delete child1 c1
where exists (select * from temp t1 where c1.id=t1.id);
Delete child13 c13
where exists (select * from temp t1 where c13.id=t1.id);
There are 330M profiles are there need to be purged so it will take long time (3+ months) to delete these profiles and generating gobs of redo. Business wants to purge this data quicker.
In some forums, I have seen approach of just retaining required data. Basically, it says that creating a one temp table holds required database. Then we truncate source table and copy data from temp table. The problem with this approach is that it requires outage which we can’t afford it. Also, we need to same thing for 13 tables. I presume that it’s going to take extended outage.
I just want to find out is there any fast way purging the data. I have been looking for this since couple of weeks but no luck. Any help really appreciated.