Ooooh I see thanks for clarifying :-) Soumaya
On Thu, 1 Apr 2021, 17:34 Mike Bayer, <mike...@zzzcomputing.com> wrote: > > > On Thu, Apr 1, 2021, at 11:20 AM, Soumaya Mauthoor wrote: > > Hello Mike > > Thanks for quick response! I don't have postgres installed right now so I > tried with sqlite, which is also autocommit by default. Example > > > ahha - that's again a very specific quirk of the pysqlite driver that it > does not autobegin the transaction if DDL is encountered, which is a bug in > the driver, see https://bugs.python.org/issue9924 > > This autocommit situation has been mostly unchanged since I first started > SQLAlchemy in 2005. So I've been working with this behavior literally > every day for sixteen years with a dozen or more DBAPI drivers. It's > safe to trust I know what i am speaking of ! :) > > > > > > > > : > > >>> from sqlalchemy import text, create_engine > >>> e = create_engine('sqlite:///foo.db') > >>> with e.connect() as conn: conn.execute(text('create table test(int > col1)')) > ... > <sqlalchemy.engine.cursor.LegacyCursorResult object at 0x7f6257fba7c0> > >>> e.execute('select * from test').fetchall() > [] > > I didn't commit the transaction, but it seems to have autocommited since I > can query it in the following query? > > Soumaya > > Le jeu. 1 avr. 2021 à 15:27, Mike Bayer <mike...@zzzcomputing.com> a > écrit : > > > > > On Thu, Apr 1, 2021, at 10:06 AM, sumau wrote: > > Hello > > Following advice from this article: > https://www.oddbird.net/2014/06/14/sqlalchemy-postgres-autocommit/ > > and because we run large, consecutive queries, we set our transaction > isolation level to 'autocommit' when connecting to our postgres DB. This > means we cannot create explicit transactions and use begin() and commit(): > https://www.oddbird.net/2014/06/14/sqlalchemy-postgres-autocommit/ > > This has not a problem so far because we can create another (temporary) > connection when we do want to have a roll-backable transaction. However > since postgres DB is set to autocommit by default, I was wondering whether > setting the transaction isolation level to 'autocommit' was needlessly > complicated? > > > the Python DBAPI is transactional by default and the "autocommit" feature > of many DBAPIs is not part of the specification: > https://www.python.org/dev/peps/pep-0249/ . the psycopg2 driver, as > well as all other DBAPI drivers, are not in autocommit by default. > > > > > > > For example in the example explained here: the > https://docs.sqlalchemy.org/en/14/tutorial/dbapi_transactions.html#getting-a-connection > the query will still be committed, even if don't explicitly commit the > transaction or the transaction isolation level to 'autocommit'. > > > respectfully, that is incorrect for the DBAPI drivers included in > SQLAlchemy, provided you aren't using MySQL with MyISAM tables. try it out > > > > > > Regards > Soumaya > > > -- > SQLAlchemy - > The Python SQL Toolkit and Object Relational Mapper > > http://www.sqlalchemy.org/ > > To post example code, please provide an MCVE: Minimal, Complete, and > Verifiable Example. 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