Re: Migration from MSSQL to POSTGRESQL

Sorry, it's Oracle to POSTGRESQL migration.

I apologize for the confusion.

Please suggest based on Oracle.

On Mon, 1 Dec 2025, 14:00 Tayyab Fayyaz, <tayyab(dot)humayl(at)gmail(dot)com> wrote:

> Hello Raj,
>
> It really depends on how much of those 64 vCPUs and 250GB RAM your SQL
> Server actually uses today, and whether you’re running on a physical box or
> a virtual machine.
>
> PostgreSQL doesn’t have a 1:1 sizing formula against SQL Server. I’d first
> look at real CPU/memory usage, workload pattern (OLTP vs reporting), and
> how connections/queries behave. I’d also factor in how well we can migrate
> and map the data types and queries, because good type choices and query
> rewrites can significantly reduce resource usage.
>
> -
>
> *If it’s a physical server*, I’d start with similar hardware for
> PostgreSQL and then tune Postgres parameters (shared_buffers, work_mem,
> etc.) based on monitoring.
> -
>
> *If it’s a VM*, I’d provision a bit more capacity than the current SQL
> Server allocation to give some headroom for tuning and unexpected overhead,
> and then right-size after observing the real load in PostgreSQL.
>
> Once the migration is done and in steady use, we can monitor CPU, memory,
> and I/O in PostgreSQL and then optimise or scale down/up based on real
> metrics instead of guessing up front.
>
>
> Tayyab
>
> On Sun, Nov 30, 2025 at 11:14 PM Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at>
> wrote:
>
>> On Mon, 2025-12-01 at 08:46 +0530, Raj wrote:
>> > I am migrating from MSSQL to POSTGRESQL. In MSSQL, I am using 64 vCPU
>> and 250GB RAM.
>> > Now how much we can give in postgres?
>>
>> If these specifications worked for you with Microsoft SQL Server, use the
>> same
>> with PostgreSQL. If you can, don't use Windows.
>>
>> Yours,
>> Laurenz Albe
>>
>>
>>