inspectdb for oracle nvarchar2 could miscalculate field size 2-fold

[JorisBenschop]

Hi, I've noticed a consistent discrepancy between Oracle tables and django inspectdb results when it comes to NVARCHAR2 data types. Let's say I add this column to my table:

alter table STUDY add (TREATMENT NVARCHAR2(500));

If I then run manage.py inspectdb, I see the following result:

 treatment = models.CharField(max_length=1000, blank=True, null=True)

From the oracle docs:

The NVARCHAR2 datatype is a Unicode-only datatype. When you create a table with an NVARCHAR2 column, you supply the maximum number of characters it can hold.

Now most likely I'm making a calculation mistakes, but to me this seems that the column allows for a 500 character input, whereas Django will allow a 1000 character input instead. If this is indeed the case, I guess this is the result from the 16bit input format that NVARCHAR2 has compared to 8-bit VARCHAR2.

My apologies if this is documented, already reported or just stupidity

[Tim Graham]

Duplicate of #19884 and #17202.