Boolean columns

Dimitar Nedev dimitar.nedev at monetdbsolutions.com
Wed Oct 21 15:41:19 CEST 2015


Thanks for sending it, Stefan. Indeed, the page was quite helpful. That's how I fixed some real/float/double issues earlier.

I see, so if I've got a boolean column, calling
ATOMstorage(getColumnType(b->T->type))
where 'b' is a BAT would not sufficient to identify it as a boolean? It will return TYPE_bte (2).

OK, I'll need to push the logic a bit further.

Best,
Dimitar

> On 2015-Oct-21, at 15:14, Stefan Manegold <Stefan.Manegold at cwi.nl> wrote:
> 
> See
> https://www.monetdb.org/wiki/MonetDB_type_system
> ;-)
> 
> our MAL representation of SQL type BOOLEAN is MAL type :bit,
> and the C representation of MAL type :bit is (out) C type bit,
> which is indeed 1 byte (8 bit) wide, because we need to accommodate 3 values:
> TRUE, FALSE & NULL (NIL).
> 
> Thus, BOOLEAN columns are (should be) represented by a BAT with tail type (:)bit,
> which is (semantically) not the same as type TINYINT / (:)bte.
> 
> Best,
> Stefan
> 
> ----- On Oct 21, 2015, at 3:07 PM, Dimitar Nedev dimitar.nedev at monetdbsolutions.com wrote:
> 
>> Hey guys,
>> 
>> A boolean type column seems to fit in a byte, I guess the extra space is to
>> represent nulls (since it ain't a qubit). But does that mean that no column
>> type is actually ':bit'?
>> Given a BAT, how to distinguish between a byte (tinyint) column and a boolean
>> one?
>> 
>> Thanks,
>> Dimitar
>> 
>> 
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> 
> --
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