Yea, I copy/pasted the wrong code block, it's ALL_IND_COLUMNS of course.

As you said, it looks like this issue calls for two (quite simple) fixes: 
(1) try to avoid KeyError for index reflections in general?, (2) use 
ALL_TAB_COLS for Oracle (or ignore M_ROW$$)?

If I remember correctly, SYS_NC* columns are created typically for 
"function-based" indexes -- same as M_ROW$$ is created for ROWID indexes in 
materialized views; should both be treated the same way?

On Tuesday, 2 September 2014 16:21:46 UTC+1, Michael Bayer wrote:
>
> I think you meant “ALL_IND_COLUMNS” for indexes
>
>
> On Sep 2, 2014, at 11:13 AM, Ivan Smirnov <[email protected] 
> <javascript:>> wrote:
>
> Index query:
>
> SELECT column_name, data_type, char_length, data_precision, data_scale, 
> nullable, data_default 
> FROM ALL_TAB_COLUMNS 
> WHERE table_name = :table_name AND owner = :owner  
> ORDER BY column_id
>
> returns
>
>     INDEX_NAME  COLUMN_NAME   UNIQUENESS
> 1 I_SNAP$_FOO   M_ROW$$       UNIQUE
>
> Column query:
>
> SELECT column_name, data_type, char_length, data_precision, data_scale, 
> nullable, data_default 
> FROM ALL_TAB_COLUMNS 
> WHERE table_name = 'FOO' 
> AND owner = 'BAR'  
> ORDER BY column_id
>
> returns
>
>     COLUMN_NAME DATA_TYPE CHAR_LENGTH DATA_PRECISION DATA_SCALE NULLABLE 
> DATA_DEFAULT
> 1   A           VARCHAR2  32                                    N        <
> Long>
> 2   B           FLOAT     0           126                       N        <
> Long>
>
> However, looking at Oracle docs here: 
> http://docs.oracle.com/database/121/REFRN/refrn20277.htm#REFRN20277  -- 
> it seems like all hidden columns are specifically filtered out of 
> ALL_TAB_COLUMNS view.
>
> Instead, one could use ALL_TAB_COLS which seems to work and reveals the 
> M_ROW$$:
>
> SELECT column_name, data_type, char_length, data_precision, data_scale, 
> nullable, data_default 
> FROM ALL_TAB_COLS 
> WHERE table_name = 'FOO' 
> AND owner = 'BAR'  
> ORDER BY column_id
>
> which returns
>
>     COLUMN_NAME DATA_TYPE CHAR_LENGTH DATA_PRECISION DATA_SCALE NULLABLE 
> DATA_DEFAULT
> 1   A           VARCHAR2  32                                    N        <
> Long>
> 2   B           FLOAT     0           126                       N        <
> Long>
> 3   M_ROW$$     VARCHAR2  18                                    Y        <
> Long>
>
>
> On Tuesday, 2 September 2014 15:55:03 UTC+1, Michael Bayer wrote:
>>
>> it means that the query we do to reflect the columns in the table isn’t 
>> coming up with this one.
>>
>>
>> A possible workaround now is to just add this column explicitly:
>>
>> t = Table(‘mytable’, m, Column(‘m_row$$’, integer), autoload=True)
>>
>>
>>
>> On Sep 2, 2014, at 10:26 AM, Ivan Smirnov <[email protected]> wrote:
>>
>> So, if I understand correctly, in this example m_row$$ is a hidden column 
>> automatically generated when a materialized view is created with rowid. 
>> It's still accessible though, i.e. you can still select from it explicitly.
>>
>> On Monday, 1 September 2014 18:46:39 UTC+1, Ivan Smirnov wrote:
>>>
>>> py27/lib/python2.7/site-packages/sqlalchemy/engine/reflection.pyc in 
>>> reflecttable(self, table, include_columns, exclude_columns)
>>>     591                 cols_by_orig_name[c] if c in cols_by_orig_name
>>>     592                 else table.c[c]
>>> --> 593                 for c in columns
>>>     594             ],
>>>     595                 **dict(unique=unique))
>>>
>>> py27/lib/python2.7/site-packages/sqlalchemy/util/_collections.pyc in 
>>> __getitem__(self, key)
>>>     155
>>>     156     def __getitem__(self, key):
>>> --> 157         return self._data[key]
>>>     158
>>>     159     def __delitem__(self, key):
>>>
>>> KeyError: u'm_row$$'
>>> > 
>>> py27/lib/python2.7/site-packages/sqlalchemy/util/_collections.py(157)__getitem__()
>>>     156     def __getitem__(self, key):
>>> --> 157         return self._data[key]
>>>     158
>>>
>>>
>>> If you have an index containing a column with a non-numeric character 
>>> (like 'm_row$$'), reflection would fail as in the example above, since 
>>> table.c would not contain it.
>>>
>>> Is there any way around it?
>>>
>>> P.S. It seems to be related to this thread from 4 years ago (MS SQL):
>>>
>>> https://groups.google.com/forum/#!searchin/sqlalchemy/keyerror/sqlalchemy/BcANLqW1D04/sRPMYpDLO8oJ
>>>
>>
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>>
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