Re: Tuple concurrency issue in large objects

Well.. it seems I have to rethink about my application design. Anyway,
thank you all for your insights and suggestions.

On 12/18/2019 10:46 PM, Justin wrote:
> 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
> <mailto:tgl(at)sss(dot)pgh(dot)pa(dot)us>> wrote:
>
> Justin <zzzzz(dot)graf(at)gmail(dot)com <mailto: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
>