On Wed, Aug 5, 2020, at 8:59 AM, Zsolt Ero wrote:
> Hi,
>
> I've split a table into two tables, for performance reasons. I'd like to
> insert into both tables using the same sequence. I'm inserting using
> executemany_mode='values'.
>
> My idea is to call nextval() on the sequence before insert and fill in the
> values client side, before inserting.
>
> select nextval('mysql') FROM generate_series(1,...)
>
> Everything looks good, except for the default behaviour of SQLAlchemy to turn
> an integer + pk column into a SERIAL.
add autoincrement=False to the Column
>
> As an alternative I'm also looking at using Sequence('myseq') from
> https://docs.sqlalchemy.org/en/13/dialects/postgresql.html#sequences-serial-identity,
> but this is broken for issuing "CREATE SEQUENCE myseq" before the table
> creation, which is missing the IF NOT EXISTS part.
there's a "checkfirst" flag on Sequence.create() or Table.create() that will
check for the object ahead of time, using a separate query. To render "IF NOT
EXISTS" then just invoke the SQL: conn.execute(text("CREATE SEQ IF NOT EXISTS
..."))
>
> How can I either:
> - turn off the automatic behaviour of making a pg + int = serial?
> - add a IF NOT EXISTS to the Sequence()?
>
> Or any alternative ideas?
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
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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. See http://stackoverflow.com/help/mcve for a full description.
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