The example in delta-encoding seems incorrect

[asfimport]

In the example using delta-encoded, encoding [1, 2, 3, 4, 5], we state that

The final encoded data is:

header: 8 (block size), 1 (miniblock count), 5 (value count), 1 (first value)

block 1 (minimum delta), 0 (bitwidth), (no data needed for bitwidth 0)

I believe that the correct result should be

header: [8, 1, 5, 2]
block: [2, 0]

I.e first_value and min_delta should be 2, not 1.

This is because the zig-zag ULEB128-encoding of 1 is 2: the ULEB-128 encoding of 1 is 1, but AFAIK the zig-zag encoding of 1 is 2 (see e.g. here).

Alternatively, we could re-phrase "The final encoded data is:" to "The final data prior to zig-zag encoding is:"

Reporter: Jorge Leitão / @jorgecarleitao

_{Note: This issue was originally created as PARQUET-2028. Please see the migration documentation for further details.}