Re: Oracle to Postgres - Mailing list pgsql-admin

We did the safe thing, and sized the RDS Postgresql the same as the Linux system running Oracle 12.  Turned out to be massively over-sized.

Your mileage will certainly vary, though.

PG12 used a lot less CPU and RAM than PG12.

On Thu, Jul 11, 2024 at 9:45 PM Sam Stearns <sam.stearns@dat.com> wrote:

Thanks for all the advice on the conversion stuff!

For the resource sizing I was chasing more CPU and memory analysis then giving recommendations on right-sizing the VM.

On Fri, Jul 12, 2024 at 10:53 AM Ron Johnson <ronljohnsonjr@gmail.com> wrote:

On Thu, Jul 11, 2024 at 8:02 PM Sam Stearns <sam.stearns@dat.com> wrote:

Howdy,

We have a project to migrate our Oracle databases that are hosted on an Oracle Database Appliance to Postgres hosted on a Linux VM.  Questions:

1. Is there a tool out there that we can use to analyze resource sizing on the Appliance that will give resource sizing recommendations for the VM?

The appliance doesn't tell you how much space your database uses???

Anyway, we converted an 8TB on-prem Oracle 12 db (heavy on CLOBs) to RDS Postgresql 12; the resulting db was about 6TB.  I'm sure that vanilla PG would be about the same size (or smaller now, since compression on dupes-allowed b-tree indices is much better now than in PG 12).

 

1. Is there a schema conversion tool or similar out there that we can use to convert Oracle ==> Postgres?

As Keith said, Google is your friend.

That's how I found ora2pg, which we used in our conversion project (for the data only; someone had to rewrite all the stored procedures).

If you use ora2pg, remember to tell it to convert all of the NUMERIC(38,0) columns to BIGINT.

--

Samuel Stearns
Lead Database Administrator
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