Inserting with billion of rows faster
Date: Sun, 28 Mar 2021 11:07:18 +0530
Message-ID: <CAKna9VZba_H9RDys=Xn1pxhHKykYLoS9fMAR0LjwWtouUE1o3A_at_mail.gmail.com>
Hi Listers, we have one process in which we load ~50million daily (using direct path insert.. INSERT APPEND ) to a target table which holds
~20billion rows(~1TB in size)) and is list -hash composite partitioned. ~2
list partition and ~2048 hash subpartitions. It has 4 indexes out of those one is a composite primary key comprising of 5 columns.We have that data load job failing since ~15-20 days without notice and it thus accumulated
~billion rows and the load process is now failing with (Ora-01628 max
extent 32765 reached for rollback segment).
So we thought of running it in a bulk collect method(append_values hint)
and commit in chunks of ~1million. But during that process we endup seeing
the data load is significantly slower , it was inserting ~1million rows in
~40minutes. And we were not able to understand the reason but the wait
events were all showing "cell single block physical read" and the object
was the target load object. Means it was the INSERt which was struggling.
So we now endup having partial data loaded to the target i.e. around
~40-50million loaded to the target. And as it has a primary key , we have
to delete the ~40-50million rows from the target table and then reload it.
I was thinking if we should do the delete in bulk method with a chunk of 1million , but again that will happen in a single thread and will be significantly slow. So what is the best way to have those ~40-50million data deleted from the target table(which holds a total ~20billion rows)?
And then I was also thinking , if we could make the index unusable and perform the delete and then data load(which would happen with almost zero UNDo in absence of INDEXes) , but then in that case it seems that DELETE will need the PK index to fetch the rowids so we cant get rid of the PK index then. So what is the best approach to go for the delete and data
load here without breaking data consistency in the target table?So wanted to understand what is the best/faster approach to go for delete and data load in this situation?
Regards
Lok
-- http://www.freelists.org/webpage/oracle-lReceived on Sun Mar 28 2021 - 07:37:18 CEST