Re: Row not immediately visible after commit

Thanks Adrian. This is 'vanilla' postgres as far as I know (unlike their
postgres-flavoured Aurora product).

b2bc_owner(at)b2bcreditonline=> select version();
version
---------------------------------------------------------------------------------------------------------
PostgreSQL 13.1 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.8.5
20150623 (Red Hat 4.8.5-11), 64-bit

Steve

On Tue, Mar 30, 2021 at 10:52 AM Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com>
wrote:

> On 3/29/21 4:39 PM, Steve Baldwin wrote:
> > Hi all,
> >
> > I know this is going to sound weird/unbelievable, but I'm trying to come
> > up with an explanation for what I've observed.
> >
> > First, a couple of data points. The instance is running on AWS RDS and
> > is on version 13.1. All my timestamps and elapsed times were taken from
> > the postgres log (converted to my local tz).
> >
> > 2021-03-30 05:47:40.989+11 Session A begins a new transaction
> > 2021-03-30 05:47:41.006+11 Session A inserts a single row into table A
> > 2021-03-30 05:47:41.031+11 Session A inserts two rows into table B
> > 2021-03-30 05:47:41.039+11 Session A commits (duration = 3.022 ms)
> >
> > 2021-03-30 05:47:41.082+11 Session B begins a new transaction
> > 2021-03-30 05:47:41.083+11 Session B fetches one of the inserted rows
> > from table B
> > 2021-03-30 05:47:41.085+11 Session B attempts to fetch the inserted row
> > from table A using the primary key. Fetch returns zero rows.
> > 2021-03-30 05:47:41.087+11 Session B aborts the transaction with rollback
> >
> > 2021-03-30 05:47:42.143+11 Session C begins a new transaction
> > 2021-03-30 05:47:42.146+11 Session C fetches the same row as session B
> above
> > 2021-03-30 05:47:42.228+11 Session C attempts the same query on table A
> > as session B above. The fetch returns 1 row, and session C continues
> > processing.
> >
> > I can't imagine how Session B could fail to fetch the row from table A
> > given that the commit has completed prior to Session B starting its
> > transaction.
> >
> > Any suggestions?
>
> Ask AWS support.
>
> >
> > Thanks,
> >
> > Steve
>
>
> --
> Adrian Klaver
> adrian(dot)klaver(at)aklaver(dot)com
>