diff --git a/docs/ref/databases.txt b/docs/ref/databases.txt
index 1b60123..718d1be 100644
a
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b
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for the field. This affects :class:`~django.db.models.CharField`,
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500 | 500 | :class:`~django.db.models.SlugField` and |
501 | 501 | :class:`~django.db.models.CommaSeparatedIntegerField`. |
502 | 502 | |
| 503 | ``TextField`` limitations |
| 504 | ~~~~~~~~~~~~~~~~~~~~~~~~~ |
| 505 | |
| 506 | MySQL can index only the first N chars of a ``BLOB`` or ``TEXT`` column. Since |
| 507 | ``TextField`` doesn't have a defined length, you can't mark it as |
| 508 | ``unique=True``. |
| 509 | |
503 | 510 | .. _mysql-fractional-seconds: |
504 | 511 | |
505 | 512 | Fractional seconds support for Time and DateTime fields |