Re: Row not immediately visible after commit

RDS is also a modified version of Postgresql, just not as modified as Aurora.

On 3/29/21 7:06 PM, Steve Baldwin wrote:
> 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
> <mailto: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 <mailto:adrian(dot)klaver(at)aklaver(dot)com>
>

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