Re: Exporting TBs of data in Oracle schema/database into CSV format to migrate into PostgreSQL

On Mon, Apr 20, 2020, 8:39 AM Avinash Kumar <avinash(dot)vallarapu(at)gmail(dot)com>
wrote:

> Hi,
> On Mon, Apr 20, 2020 at 12:31 PM Scott Ribe <scott_ribe(at)elevated-dev(dot)com>
> wrote:
>
>> So, the big question is: how much downtime can you afford on the current
>> Oracle DB?
>>
>> Yes, you should investigate the most efficient way to transfer data, but
>> with TBs it will still be significant time. If you can afford the down
>> time, great--kill all other connections to Oracle and go for it. If not,
>> that's more complicated since you'll have to figure out a way to track and
>> apply changes that happen during the copy...
>>
> If downtime is a concern, then, start a transaction on PG, using isolation
> level - REPEATABLE READ, get the SCN number from Oracle and copy the
> existing data from each table (table by table) using FDW for the initial
> data load. And then, if you have Oracle GG license, start the replicat from
> that SCN so that the data gets to sync eventually.
> And then, when all the tables are in Sync, go ahead and switch your Apps.
> If we dont have GG license, we need to look for some other extensions or
> Kafka or something else that could do this job. Remember, migration is
> always challenging when lots of data is involved, and there never exists a
> direct magic.
>
>
> --
> Regards,
> Avinash Vallarapu
> +1-902-221-5976
>