Re: Tuple concurrency issue in large objects

I agree completely,

I do not think Postgresql is a good fit for Shalini based on the
conversation so far

tracking Concurrency is going to be a killer... But i see the temptation
to use a DB for this as the updates are ACID less likely to corrupted data
for X reason

On Wed, Dec 18, 2019 at 12:12 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Justin <zzzzz(dot)graf(at)gmail(dot)com> writes:
> > I now see what is causing this specific issue...
> > The update and row versions is happening on 2kb chunk at a time, That's
> > going to make tracking what other clients are doing a difficult task.
>
> Yeah, it's somewhat unfortunate that the chunkiness of the underlying
> data storage becomes visible to clients if they try to do concurrent
> updates of the same large object. Ideally you'd only get a concurrency
> failure if you tried to overwrite the same byte(s) that somebody else
> did, but as it stands, modifying nearby bytes might be enough --- or
> not, if there's a chunk boundary between.
>
> On the whole, though, it's not clear to me why concurrent updates of
> sections of large objects is a good application design. You probably
> ought to rethink how you're storing your data.
>
> regards, tom lane
>