Re: Consecutive Inserts Freeze Execution of Psycopg3 - Mailing list psycopg
| From | Michael P. McDonnell |
|---|---|
| Subject | Re: Consecutive Inserts Freeze Execution of Psycopg3 |
| Date | |
| Msg-id | CAHmCLHrDTDhQnof4nCD34vqY+kLmtY-FHkwMLU30V=0wDxhvKA@mail.gmail.com Whole thread Raw |
| In response to | Re: Consecutive Inserts Freeze Execution of Psycopg3 (Adrian Klaver <adrian.klaver@aklaver.com>) |
| List | psycopg |
Hey Adrian -
Just wanted to say thank you again for helping me with getting the session stuff structured appropriately. I actually found my issue and it turns out that while my code is suboptimal in a lot of ways - it was actually a separate database issue as a whole that I'm just now tracking down.
Just thought you'd like to know that it was not a psycopg(3 or 2) issue, not a sqlalchemy issue, and it has something to do with how the queries seem to work.
And the technical info (not an ask, just an inform)
The queries are just an ETL from one table to another based on how the data needs to be accessed. If I trunc all the tables, and load the originating table - the first ETL works fine (table1 -> table2).
However - when I then call the 2nd ETL from table2 to table3 - the query "freezes". I'm still looking into what that means and how to find what's going on.
However - when I then call the 2nd ETL from table2 to table3 - the query "freezes". I'm still looking into what that means and how to find what's going on.
If I cancel the execution of that query and re-run the 2nd ETL (table2 to table3) - it runs in the amount of time I expected (2-3 seconds).
So this fundamentally was never about a session, or commits, or anything else; those were working as expected - the query itself was just hung up in the server doing its "thing".
Anywho - hopefully someone is googling and this pops up and helps them look at the problem differently. Have a great day.
-Mike
On Sun, Apr 23, 2023 at 8:20 PM Adrian Klaver <adrian.klaver@aklaver.com> wrote:
On 4/23/23 18:06, Michael P. McDonnell wrote:
> So I appreciate you're trying to point to the official source of the
> documentation; but one place where FastAPI might be a place of
This is the first mention of using FastAPI.
> inspiration is the consistent building of a single use case example to
> show how one might do something more complex. Given the docs available -
> I have no idea how I might take a dict and generate an UPDATE statement
> using the sql.SQL API you have.
Some pseudo-code showing what you are trying to achieve would be useful.
>
> And I'm genuinely not trying to nitpick here, I'm relatively new to
> Python and am more or less winging it and the documentation immediately
> available doesn't exactly spell out *all the things*; So again - thank
> you for your help in getting me over the original hump; I appreciate it.
It is tough for documentation to cover all possible user cases. I have
found the best way for me is to write a flow chart of what I want to do
and then search for the commands/code that gets me there.
>
> On Sun, Apr 23, 2023 at 7:59 PM Adrian Klaver <adrian.klaver@aklaver.com
> <mailto:adrian.klaver@aklaver.com>> wrote:
>
> On 4/23/23 17:26, Michael P. McDonnell wrote:
> > Thanks Adrian -
> > I appreciate it; and I've been pouring through documentation to
> try and
> > get to this point.
> > I can't help but feel I'm doing it "wrong" but no website I can find
> > recently seems to have a "right" way of doing things that's
> reasonably
> > kept up.
> > It would be nice if "wrong" had a way of shooting me in the foot
> with
> > verbose errors or warnings.
>
> Start here:
>
> https://www.psycopg.org/psycopg3/docs/basic/index.html
> <https://www.psycopg.org/psycopg3/docs/basic/index.html>
>
> and work through the sections in order.
>
> >
> > -Mike
> >
> > On Sun, Apr 23, 2023 at 7:15 PM Adrian Klaver
> <adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>
> > <mailto:adrian.klaver@aklaver.com
> <mailto:adrian.klaver@aklaver.com>>> wrote:
> >
> > On 4/23/23 14:55, Michael P. McDonnell wrote:
> > > That helped a ton, I don't understand why I've had to
> rewrite the
> > crap
> > > out of all of this to get it to work (dropping SqlAlchemy,
> upgrading
> > > from psycopg2 to psycopg, etc...) but it's working now and
> I can
> > work
> > > around it. Thank you.
> >
> > Well:
> >
> > 1) SQLAlchemy is an ORM that tries to make all databases look
> the same.
> >
> > 2) psycopg2 != psycopg. For details see:
> >
> > https://www.psycopg.org/psycopg3/docs/basic/from_pg2.html
> <https://www.psycopg.org/psycopg3/docs/basic/from_pg2.html>
> > <https://www.psycopg.org/psycopg3/docs/basic/from_pg2.html
> <https://www.psycopg.org/psycopg3/docs/basic/from_pg2.html>>
> >
> > 3) It would have been more of a surprise if you did not have
> to change
> > anything.
> >
> > 4) And this
> >
> > with self.connection.cursor() as conn:
> >
> > was just plain wrong. You where trying to make a cursor be a
> connection
> > and that is not going to work.
> >
> >
> > >
> > >
> > > On Sun, Apr 23, 2023 at 4:25 PM Adrian Klaver
> > <adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>
> <mailto:adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>>
> > > <mailto:adrian.klaver@aklaver.com
> <mailto:adrian.klaver@aklaver.com>
> > <mailto:adrian.klaver@aklaver.com
> <mailto:adrian.klaver@aklaver.com>>>> wrote:
> > >
> > > On 4/23/23 13:45, Michael P. McDonnell wrote:
> > > > Python 3.10.6
> > > > psycopg library 3.1.8
> > > >
> > > > Running consecutive inserts sourced in files.
> > > > All inserts are of the same format:
> > > >
> > > > INSERT INTO _____ (field1, field2, field3)
> > > > SELECT field1, field2, field3 FROM ____, Join ___, join
> > ___ etc...
> > > >
> > > > The code I've written is this:
> > > >
> > > > for qi in range(qlen):
> > > > query = queries[qi]
> > > > qparams = params[qi]
> > > > with self.connection.cursor() as conn:
> > > > conn.execute(query, qparams)
> > >
> > > In above you are running the context manager(with)
> over the
> > cursor not
> > > the connection. This will not automatically commit the
> > transaction. You
> > > will need to either explicitly do connection.commit()
> or use
> > the with
> > > over the connection per:
> > >
> > >
> https://www.psycopg.org/psycopg3/docs/basic/transactions.html
> <https://www.psycopg.org/psycopg3/docs/basic/transactions.html>
> >
> <https://www.psycopg.org/psycopg3/docs/basic/transactions.html
> <https://www.psycopg.org/psycopg3/docs/basic/transactions.html>>
> > >
> >
> <https://www.psycopg.org/psycopg3/docs/basic/transactions.html
> <https://www.psycopg.org/psycopg3/docs/basic/transactions.html>
> >
> <https://www.psycopg.org/psycopg3/docs/basic/transactions.html
> <https://www.psycopg.org/psycopg3/docs/basic/transactions.html>>>
> > >
> > > >
> > > > When I run the queries in dbeaver - the first query
> takes
> > 120s (it's
> > > > 1.9M rows), the second query takes 2s (7000 rows).
> > > > When I run the queries in python - it freezes on the
> > second query.
> > > >
> > > > Any guidance on how to attack this would be awesome
> as I have
> > > re-written
> > > > my code a dozen times and am just slinging mud to
> see what
> > sticks.
> > >
> > > --
> > > Adrian Klaver
> > > adrian.klaver@aklaver.com
> <mailto:adrian.klaver@aklaver.com> <mailto:adrian.klaver@aklaver.com
> <mailto:adrian.klaver@aklaver.com>>
> > <mailto:adrian.klaver@aklaver.com
> <mailto:adrian.klaver@aklaver.com> <mailto:adrian.klaver@aklaver.com
> <mailto:adrian.klaver@aklaver.com>>>
> > >
> >
> > --
> > Adrian Klaver
> > adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>
> <mailto:adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>>
> >
>
> --
> Adrian Klaver
> adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>
>
--
Adrian Klaver
adrian.klaver@aklaver.com