On Dec 23, 2013, at 9:29 AM, Sibylle Koczian <[email protected]> wrote:
> Am 21.12.2013 16:27, schrieb Michael Bayer: >> In the case of using Postgresql, the type >> sqlalchemy.dialects.postgresql.INTERVAL takes over wherever you might >> have used a sqlalchemy.Interval type. In this case, psycopg2 is >> what’s doing whatever conversions are occurring here - if a result >> row type has the Postgres OID for an “INTERVAL”, psycopg2 jumps in >> and does the conversion to timedelta. This isn’t on the SQLAlchemy >> side. If psycopg2 is doing the wrong thing you might want to look >> over on their side for updates or bug reports. >> > I don't really know if psycopg2 is doing the wrong thing. Py-postgresql does > the same conversion. This might be viewed as a problem with > datetime.timedelta which isn't suitable for intervals of several months. maybe you want to check on that because I’m not familiar with any such limitation in datetime.timedelta, it essentially stores a number of days. Below is an example using timedeltas of twelve years, eight months, and four days: >>> import datetime >>> datetime.datetime(1992, 12, 19) - datetime.datetime(1980, 4, 15) datetime.timedelta(4631) >>> d1 = datetime.datetime(1992, 12, 19) - datetime.datetime(1980, 4, 15) >>> datetime.datetime(1992, 12, 19) + d1 datetime.datetime(2005, 8, 24, 0, 0)
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