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* Migration from MSSQL to POSTGRESQL
@ 2025-12-01 03:16 Raj <[email protected]>
2025-12-01 07:13 ` Re: Migration from MSSQL to POSTGRESQL Laurenz Albe <[email protected]>
0 siblings, 1 reply; 7+ messages in thread
From: Raj @ 2025-12-01 03:16 UTC (permalink / raw)
To: Pgsql-admin <[email protected]>
Hi all,
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?
^ permalink raw reply [nested|flat] 7+ messages in thread
* Re: Migration from MSSQL to POSTGRESQL
2025-12-01 03:16 Migration from MSSQL to POSTGRESQL Raj <[email protected]>
@ 2025-12-01 07:13 ` Laurenz Albe <[email protected]>
2025-12-01 08:27 ` Re: Migration from MSSQL to POSTGRESQL Tayyab Fayyaz <[email protected]>
0 siblings, 1 reply; 7+ messages in thread
From: Laurenz Albe @ 2025-12-01 07:13 UTC (permalink / raw)
To: Raj <[email protected]>; Pgsql-admin <[email protected]>
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
^ permalink raw reply [nested|flat] 7+ messages in thread
* Re: Migration from MSSQL to POSTGRESQL
2025-12-01 03:16 Migration from MSSQL to POSTGRESQL Raj <[email protected]>
2025-12-01 07:13 ` Re: Migration from MSSQL to POSTGRESQL Laurenz Albe <[email protected]>
@ 2025-12-01 08:27 ` Tayyab Fayyaz <[email protected]>
2025-12-01 08:37 ` Re: Migration from MSSQL to POSTGRESQL Raj <[email protected]>
0 siblings, 1 reply; 7+ messages in thread
From: Tayyab Fayyaz @ 2025-12-01 08:27 UTC (permalink / raw)
To: Laurenz Albe <[email protected]>; +Cc: Raj <[email protected]>; Pgsql-admin <[email protected]>
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 <[email protected]>
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
>
>
>
^ permalink raw reply [nested|flat] 7+ messages in thread
* Re: Migration from MSSQL to POSTGRESQL
2025-12-01 03:16 Migration from MSSQL to POSTGRESQL Raj <[email protected]>
2025-12-01 07:13 ` Re: Migration from MSSQL to POSTGRESQL Laurenz Albe <[email protected]>
2025-12-01 08:27 ` Re: Migration from MSSQL to POSTGRESQL Tayyab Fayyaz <[email protected]>
@ 2025-12-01 08:37 ` Raj <[email protected]>
2025-12-01 09:16 ` Re: Migration from MSSQL to POSTGRESQL Laurenz Albe <[email protected]>
2025-12-01 14:45 ` Re: Migration from MSSQL to POSTGRESQL Ron Johnson <[email protected]>
0 siblings, 2 replies; 7+ messages in thread
From: Raj @ 2025-12-01 08:37 UTC (permalink / raw)
To: Tayyab Fayyaz <[email protected]>; +Cc: Laurenz Albe <[email protected]>; Pgsql-admin <[email protected]>
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, <[email protected]> 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 <[email protected]>
> 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
>>
>>
>>
^ permalink raw reply [nested|flat] 7+ messages in thread
* Re: Migration from MSSQL to POSTGRESQL
2025-12-01 03:16 Migration from MSSQL to POSTGRESQL Raj <[email protected]>
2025-12-01 07:13 ` Re: Migration from MSSQL to POSTGRESQL Laurenz Albe <[email protected]>
2025-12-01 08:27 ` Re: Migration from MSSQL to POSTGRESQL Tayyab Fayyaz <[email protected]>
2025-12-01 08:37 ` Re: Migration from MSSQL to POSTGRESQL Raj <[email protected]>
@ 2025-12-01 09:16 ` Laurenz Albe <[email protected]>
1 sibling, 0 replies; 7+ messages in thread
From: Laurenz Albe @ 2025-12-01 09:16 UTC (permalink / raw)
To: Raj <[email protected]>; Tayyab Fayyaz <[email protected]>; +Cc: Pgsql-admin <[email protected]>
On Mon, 2025-12-01 at 14:07 +0530, Raj wrote:
> Please suggest based on Oracle.
My recommendation is the same, no matter from which database system you are migrating.
Yours,
Laurenz Albe
^ permalink raw reply [nested|flat] 7+ messages in thread
* Re: Migration from MSSQL to POSTGRESQL
2025-12-01 03:16 Migration from MSSQL to POSTGRESQL Raj <[email protected]>
2025-12-01 07:13 ` Re: Migration from MSSQL to POSTGRESQL Laurenz Albe <[email protected]>
2025-12-01 08:27 ` Re: Migration from MSSQL to POSTGRESQL Tayyab Fayyaz <[email protected]>
2025-12-01 08:37 ` Re: Migration from MSSQL to POSTGRESQL Raj <[email protected]>
@ 2025-12-01 14:45 ` Ron Johnson <[email protected]>
2025-12-02 19:48 ` Re: Migration from MSSQL to POSTGRESQL Raj <[email protected]>
1 sibling, 1 reply; 7+ messages in thread
From: Ron Johnson @ 2025-12-01 14:45 UTC (permalink / raw)
To: Pgsql-admin <[email protected]>
In the one Oracle -> Postgresql migration I did (where I came in after the
AWS RDS Postgresql VMs were already sped'ed and were 1:1 the same as the
Oracle servers:
- disk usage was 1/3 lower
- both CPU and RAM were 75% over-specified. (They could be chopped in half
and performance would still be good.)
But, of course, your mileage not only might vary, but *it will vary*.
On Mon, Dec 1, 2025 at 3:38 AM Raj <[email protected]> wrote:
> 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, <[email protected]> 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 <[email protected]>
>> 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
>>>
>>>
>>>
--
Death to <Redacted>, and butter sauce.
Don't boil me, I'm still alive.
<Redacted> lobster!
^ permalink raw reply [nested|flat] 7+ messages in thread
* Re: Migration from MSSQL to POSTGRESQL
2025-12-01 03:16 Migration from MSSQL to POSTGRESQL Raj <[email protected]>
2025-12-01 07:13 ` Re: Migration from MSSQL to POSTGRESQL Laurenz Albe <[email protected]>
2025-12-01 08:27 ` Re: Migration from MSSQL to POSTGRESQL Tayyab Fayyaz <[email protected]>
2025-12-01 08:37 ` Re: Migration from MSSQL to POSTGRESQL Raj <[email protected]>
2025-12-01 14:45 ` Re: Migration from MSSQL to POSTGRESQL Ron Johnson <[email protected]>
@ 2025-12-02 19:48 ` Raj <[email protected]>
0 siblings, 0 replies; 7+ messages in thread
From: Raj @ 2025-12-02 19:48 UTC (permalink / raw)
To: Ron Johnson <[email protected]>; +Cc: Pgsql-admin <[email protected]>
Hi Ron, it's On premises. Not cloud.
On Mon, 1 Dec 2025, 20:15 Ron Johnson, <[email protected]> wrote:
>
> In the one Oracle -> Postgresql migration I did (where I came in after the
> AWS RDS Postgresql VMs were already sped'ed and were 1:1 the same as the
> Oracle servers:
> - disk usage was 1/3 lower
> - both CPU and RAM were 75% over-specified. (They could be chopped in
> half and performance would still be good.)
>
> But, of course, your mileage not only might vary, but *it will vary*.
>
> On Mon, Dec 1, 2025 at 3:38 AM Raj <[email protected]> wrote:
>
>> 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, <[email protected]> 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 <[email protected]>
>>> 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
>>>>
>>>>
>>>>
>
> --
> Death to <Redacted>, and butter sauce.
> Don't boil me, I'm still alive.
> <Redacted> lobster!
>
^ permalink raw reply [nested|flat] 7+ messages in thread
end of thread, other threads:[~2025-12-02 19:48 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz follow: Atom feed)
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2025-12-01 03:16 Migration from MSSQL to POSTGRESQL Raj <[email protected]>
2025-12-01 07:13 ` Laurenz Albe <[email protected]>
2025-12-01 08:27 ` Tayyab Fayyaz <[email protected]>
2025-12-01 08:37 ` Raj <[email protected]>
2025-12-01 09:16 ` Laurenz Albe <[email protected]>
2025-12-01 14:45 ` Ron Johnson <[email protected]>
2025-12-02 19:48 ` Raj <[email protected]>
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