Re: PostgreSQL Active-Active Clustering

On Mon, Jul 15, 2024 at 3:28 PM Christophe Pettus <xof(at)thebuild(dot)com> wrote:

>
> > On Jul 15, 2024, at 12:06, Sarkar, Subhadeep <subhadeepsarkar(at)kpmg(dot)com>
> wrote:
> >
>
[snip]

> > • In the Community edition of PostgreSQL is it possible to setup a
> cluster where all the nodes are able to concurrently read-write the
> underlying database image using NATIVE features (i.e. without using any
> extensions or external components or usage of Kubernetes/Dockers).
>
[snip]

> No product, either commercial or open-source, provides the last one
> (read-write shared storage), although there are commercial products that
> provide for a shared-storage model single-writer, multiple-reader model
> (for example, Amazon Aurora).
>

This "lack of products" puzzles me, because DEC was doing this with VAX
(then Alpha and Itanium) clusters 40 years ago via a Distributed Lock
Manager integrated deep into VMS. Their Rdb and (CODASYL) DBMS products
used those functions extensively.

(In the late 1990s, they sold the DLM code to Oracle, which is where RAC
comes from.)

It was shared-disk, multiple-writer, because the DLM allowed for locking at
the row level. Thus, a half dozen cluster nodes could hold write locks on
different rows on the same data page.