Question

Does anybody know what the main difference between session.commit() and session.flush() in SQLAlchemy is?

Answer 1

Here are some relevant quotes from the documentation.

flush:

When the Session is used with its default configuration, the flush
step is nearly always done transparently. Specifically, the flush
occurs before any individual Query is issued, as well as within the
commit() call before the transaction is committed.

commit:

commit() is used to commit the current transaction. It always issues
flush() beforehand to flush any remaining state to the database; this
is independent of the “autoflush” setting. If no transaction is
present, it raises an error. Note that the default behavior of the
Session is that a “transaction” is always present; this behavior can
be disabled by setting autocommit=True. In autocommit mode, a
transaction can be initiated by calling the begin() method.