Re: Boolean columns

On 21/10/15 15:41, Dimitar Nedev wrote:

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).

The name ATOMstorage should tell you a lot: it's about *storage*, not semantics. A bit uses the same amount of storage as a bte, but that doesn't mean those bytes are interpreted the same. It may well be that you shouldn't use ATOMstorage here.

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

Best, Dimitar

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On 2015-Oct-21, at 15:14, Stefan Manegold 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@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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