I think the behavior is undefined. For an empty string array the offsets buffer generally shouldn't be referenced.
On Mon, May 9, 2022 at 10:27 AM Sasha Krassovsky <krassovskysa...@gmail.com> wrote: > Hello, > I think an empty string array will have an offsets buffer of length 1 with > the value 0. > > Sasha Krassovsky > > > 9 мая 2022 г., в 05:23, Yang hao <1371656737...@gmail.com> написал(а): > > > > For an empty (list, binary, string) array, what should the offsets > buffer be? Empty buffer or a buffer containing a single zero? Or both are > valid? > > > > There is some related information I found: > > > > 1. In the Apache Arrow Format: link< > https://arrow.apache.org/docs/format/Columnar.html#variable-size-binary-layout > > > > > > The offsets buffer contains length + 1 signed integers (either 32-bit or > 64-bit, depending on the logical type). > > Generally the first slot in the offsets array is 0, and the last slot is > the length of the values array. > > > > 1. A related issue in arrow-rs: link< > https://github.com/apache/arrow-rs/issues/1620> > > > > We find that some test data in arrow-testing has empty offsets buffer > (but not 100% sure). > > > > 1. In arrow2 (rust), offsets buffer cannot be empty: > > > > Link1< > https://github.com/jorgecarleitao/arrow2/blob/8fb3b8d3f05cdc3d51f1314cfeb9bec39196789c/src/array/specification.rs#L101 > > > > > > Link2< > https://github.com/jorgecarleitao/arrow2/blob/main/src/io/ipc/read/array/binary.rs#L45 > > > > > > 1. In arrow (c++), (sorry I am not familiar with the c++ > implementation): > > > > Link< > https://github.com/apache/arrow/blob/c70426f73326b3852d1bd7c31d98be4743f3fcba/cpp/src/arrow/array/array_nested.cc#L111-L113 > > > > > > Looking forward to your opintions! > > > > > > Regards, > > Remzi >
