Re: [Rust] [Format] Should Null Bitmaps be Padded to 8 or 64 Bits?

2019-04-26 Thread Wes McKinney
The Buffer struct / metadata need not be a multiple of 8 bytes necessarily but you must write padding bytes when emitting the IPC protocol. So if your validity bitmap is 2 bytes in-memory then you must write at least 6 more bytes of padding on the wire. On Fri, Apr 26, 2019, 3:48 PM Micah Kornfiel

Re: [Rust] [Format] Should Null Bitmaps be Padded to 8 or 64 Bits?

2019-04-26 Thread Micah Kornfield
Hi Neville, Here is my understanding. Per the spec [1], 8 bytes of padding is allowed/required but 64 bytes is recommended (Is "bits" in your e-mail is a typo?). The main rationale is to allow SIMD instructions. For actual record batches only padding to a multiple of 8-bytes are required [2]. N

[Rust] [Format] Should Null Bitmaps be Padded to 8 or 64 Bits?

2019-04-26 Thread Neville Dipale
Hi Arrow developers, I'm currently working on IPC in Rust, specifically reading Arrow files. I've noticed that null buffers/bitmaps are always padded to 64 bits (from pyarrow, not sure about others), while in Rust we pad to 8 bits. 1. Is this fine re. Rust per the spec? I'm having issues with re