Re: Tuple concurrency issue in large objects - Mailing list pgsql-general

From Shalini
Subject Re: Tuple concurrency issue in large objects
Date
Msg-id 416c2475-7782-f410-6f67-e99bd36aa688@saralweb.com
Whole thread Raw
In response to Re: Tuple concurrency issue in large objects  (Justin <zzzzz.graf@gmail.com>)
List pgsql-general
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@sss.pgh.pa.us> wrote:
Justin <zzzzz.graf@gmail.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

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