As far as I can tell, the alignment padding used in an IPC stream/file isn't stored explicitly, and not really "inferrable", though maybe technically possible if you calculated what bytes are *necessary* given a buffer's data vs. what's actually stored.
Just wondering if this has been brought up at all to store explicitly; it came up in the Julia implementation when considering "appending" record batches to an IPC stream that has already been written to disk; we originally thought we would need to match alignment used in previously written record batches, but upon further reflection, it seems like technically it wouldn't matter since all buffers have the exact byte counts written anyway. Just wasn't sure if it would be breaking implicit assumptions by consumers somewhere if they happened to get an IPC stream w/ record batches that mixed, for example, 8-byte and 64-byte alignments. -Jacob
