Hi Wes,

You're right, I just realized that. I think the alignment issue might be in some unrelated code, actually. From what I can tell the the arrow writers are aligning buffers correctly; if not I'll open a bug.


Thanks,

Emilio

On 08/08/2017 09:15 AM, Wes McKinney wrote:
hi Emilio,

 From your description, it isn't clear why 8-byte alignment is causing
a problem (as compare with 64-byte alignment). My understanding is
that JavaScript's TypedArray classes range in size from 1 to 8 bytes.

The starting offset for all buffers should be 8-byte aligned, if not
that is a bug. Could you clarify?

- Wes

On Tue, Aug 8, 2017 at 8:52 AM, Emilio Lahr-Vivaz <elahrvi...@ccri.com> wrote:
After looking at it further, I think only the buffers themselves need to be
aligned, not the metadata and/or schema. Would there be any problem with
changing the alignment to 64 bytes then?

Thanks,

Emilio


On 08/08/2017 08:08 AM, Emilio Lahr-Vivaz wrote:
I'm looking into buffer alignment in the java writer classes. Currently
some files written with the java streaming writer can't be read due to the
javascript TypedArray's restriction that the start offset of the array must
be a multiple of the data size of the array type (i.e. Int32Vectors must
start on a multiple of 4, Float64Vectors must start on a multiple of 8,
etc). From a cursory look at the java writer, I believe that the schema that
is written first is not aligned at all, and then each record batch pads out
its size to a multiple of 8. So:

1. should the schema block pad itself so that the first record batch is
aligned, and is there any problem with doing so?
2. is there any problem with changing the alignment to 64 bytes, as
recommended (but not required) by the spec?

Thanks,

Emilio


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