Is there a way to use a builder to be able to provide a bit per value LSB
as is described in the documentation? I have this already and it seems
silly to convert it to something else so that arrow can then make it the
same format as what I had to begin with. I know there is the ArrayData
class that has a make function that seems to allow me to do this but I am
trying to do things as the documentation suggest which I assumed was the
preferred method of doing this.



On Fri, Mar 22, 2019 at 8:13 AM Francois Saint-Jacques <
fsaintjacq...@gmail.com> wrote:

> Actually, this specific method seems to use a byte per value as you
> questioned. I think it's worth adding documentation and an explicit warning
> if it confused me. I'll let bkietz chime in to comment on the usage.
>
> François
>
> On Fri, Mar 22, 2019 at 10:57 AM Francois Saint-Jacques <
> fsaintjacq...@gmail.com> wrote:
>
> > Hello Felipe,
> >
> > it's a bit per value as per memory layout documentation.
> >
> > François
> >
> >
> >
> > On Fri, Mar 22, 2019 at 10:48 AM Felipe Aramburu <fel...@blazingdb.com>
> > wrote:
> >
> >> In the builder base class I see this api
> >>
> >>
> >>
> https://github.com/apache/arrow/blob/ad1697e5d25eeaff5630421f55b0120f45cf0ce1/cpp/src/arrow/array/builder_base.h#L149
> >>
> >>     // Vector append. Treat each zero byte as a nullzero. If valid_bytes
> >> is
> >> null
> >>     // assume all of length bits are valid.
> >>     void UnsafeAppendToBitmap(const uint8_t* valid_bytes, int64_t
> length)
> >>
> >> Is valid_bytes an allocation of size (int8_t) * length, using an entire
> >> byte to indicate validity for each element in the array or is this a
> null
> >> bitmask where in each byte in valid_bytes encodes 8 values, one per bit?
> >>
> >> If this is using a byte per value is there an approved way of using a
> >> builder to initialize an array using the memory layout described here
> >> https://arrow.apache.org/docs/memory_layout.html#null-bitmaps?
> >>
> >
>

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