[Twisted-Python] adbapi transaction initiation
screwtape at froup.com
Thu Dec 31 16:13:40 EST 2009
On Thu, 31 Dec 2009 12:35:49 -0500
Landreville <landreville at deadtreepages.com> wrote:
> I've just noticed the transaction_timestamp is actually way (up to
> several minutes) before the database proc gets called. I'm on
> postgresql 8.4 so the transaction_timestamp is when the transaction
> started, and I compared it against the clock_timestamp (absolute
> current time) and it is quite a bit off.
> Does adbapi start transactions before any method (ie runQuery) is
> Or should I be looking at the underlying database driver to this
I haven't looked at the code myself, but that seems a reasonable
behaviour to me:
- adbapi.ConnectionPool, as its name suggests, pre-allocates a bunch
of database connections.
- DBAPI2.0 requires that cursors default to doing things in a
- PostgreSQL natively defaults to doing things immediately, outside a
transaction, so running "BEGIN" on startup is a sensible thing for a
PostgreSQL Python module to do.
In fact, now that I think about it, I happen to know that PyPgSQL
cursors (what RedHat packagaes as "postgresql-python") execute "BEGIN"
on creation and immediately after each .rollback() or .commit(), and I
suspect other libraries like psycopg2 would do much the same thing.
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