I have just upgraded sqlalchemy and am running some tests on some old code
and getting some very strange results.
I have a table with a column defined as TIMESTAMP WITH TIMEZONE:
test_table = Table('test', metadata,
Column('id', Integer, primary_key=True),
Column('data', UnicodeText, primary_key=True),
Column('ts', DateTime(timezone=True), nullable=False),
)
And I then have a query which uses it like so (TestTable is the ORM mapping
of test_table):
session.query(extract('epoch', database.TestTable.ts))
and this is producing output like:
SELECT EXTRACT(epoch FROM test_table.ts :: timestamp);
That cast is a problem, since casting a timestamptz to a timestamp removes
the timestamp info, which means you get a different answer, since it's now
interpreted as UTC, which means the answer is (in my case) two hours off:
# select extract(epoch from '2013-06-02 11:23:45+02'::timestamptz);
date_part
------------
1370165025
(1 row)
# select extract(epoch from '2013-06-02
11:23:45+02'::timestamptz::timestamp);
date_part
------------
1370172225
(1 row)
This cast seems to have been introduced in response to
http://www.sqlalchemy.org/trac/ticket/1647 which seems to completely ignore
the WITH TIMEZONE case. I tested it on 0.5.4, but on 0.7.6 it's definitely
broken. What I don't understand is why the cast is there at all. Unless the
argument is text postgresql can work out the type by itself just fine.
I think it's a bug and if people agree I can file one. But is there a
workaround to suppress the cast?
Thanks in advance,
--
Martijn van Oosterhout <klep...@gmail.com>
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