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From: Lawrence D'Oliveiro <ldo@nz.invalid>
Newsgroups: comp.lang.python
Subject: Re: psycopg2 positioning of .commit() (Posting On Python-List
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Date: Mon, 9 Sep 2024 21:05:34 -0000 (UTC)
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On Mon, 9 Sep 2024 10:00:11 -0000 (UTC), Jon Ribbens wrote:

> On 2024-09-09, Lawrence D'Oliveiro <ldo@nz.invalid> wrote:
>
>> The database only needs to commit when it is explicitly told. Anything
>> less -- no commit.
> 
> So the Python code is half-way through a transaction when it throws a
> (non-database-related) exception and that thread of execution is
> aborted. The database connection returns to the pool ...

The DBMS connection is deleted. The DBMS discards all context created for 
this connection, including any transactions in progress. Gone.

The database structures on persistent storage are also carefully designed 
with transaction safety in mind. So any partial transaction data saved on 
persistent storage that remains after a system crash can be identified as 
such and discarded, leaving the database in its pre-transaction state.