#2443: Add IntervalField to database models
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Reporter: | Owner: Adys
ben.tucker@… | Status: new
Type: New | Component: Database layer
feature | (models, ORM)
Milestone: | Severity: Normal
Version: SVN | Keywords: IntervalField
Resolution: | interval duration DurationField
Triage Stage: Accepted | feature
Needs documentation: 0 | Has patch: 1
Patch needs improvement: 1 | Needs tests: 1
UI/UX: 1 | Easy pickings: 0
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Comment (by jpaulett):
Karen,
While Python does provide the timedelta class, there is no common SQL
implementation for storing that object in the database. PostgreSQL does
provide the INTERVAL data type, MySQL and SQLite do not have any interval
data type (I am not sure about Oracle, MSSQL, etc.).
Luckily Django makes it relatively simple to create
[https://docs.djangoproject.com/en/dev/howto/custom-model-fields/ custom
model fields]. If you are willing to be PostgreSQL-specific, you could
store timedeltas as INTERVALs (I believe the psycopg driver handles the
conversion for you).
You could also convievably pickle the timedelta instance and store that
blob in the database. This approach breaks the sorting semantics,
potentially corrupts the data across Python versions, and is completely
opaque from a pure database perspective.
Another approach is to store the data in the database as a BIGINT. This
approach has the advantage of working across databases and retains the the
expected sorting semantics. The downside to this approach from a pure
database perspective, is that you now must know the function to convert
from a BIGINT into an interval. Based upon the patches included in this
ticket, myself and several other developers created [http://django-
durationfield.readthedocs.org/ django-durationfield]. One advantage of
being a standalone app as opposed to being in core is that we can release
new features & bug fixes without having to wait for a major Django point
release.
I do not mean to speak for the core developers, but since there is no
ideal solution and since using a standalone app is extremely easy, I doubt
we will see this feature included in core anytime soon.
--
Ticket URL: <https://code.djangoproject.com/ticket/2443#comment:50>
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