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[1.8.x] Refs #2495 -- Documented that MySQL cannot have TextField(unique=True).

Backport of e8cbc2b322d873a6fe39faca18d340ce93035087 from master
This commit is contained in:
Tim Graham 2015-08-27 09:29:13 -04:00
parent b7042576f9
commit 4f83bfa9e5

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@ -500,6 +500,14 @@ for the field. This affects :class:`~django.db.models.CharField`,
:class:`~django.db.models.SlugField` and
:class:`~django.db.models.CommaSeparatedIntegerField`.
``TextField`` limitations
~~~~~~~~~~~~~~~~~~~~~~~~~
MySQL can index only the first N chars of a ``BLOB`` or ``TEXT`` column. Since
``TextField`` doesn't have a defined length, you can't mark it as
``unique=True``. MySQL will report: "BLOB/TEXT column '<db_column>' used in key
specification without a key length".
.. _mysql-fractional-seconds:
Fractional seconds support for Time and DateTime fields