Bulk skip in RunLengthBitPackingHybridDecoder / DictionaryValuesReader

[abstractdog]

Motivation

Make Hive leverage bulk skip when implementing probe decode for Parquet, similarly to https://issues.apache.org/jira/browse/HIVE-22731, which was about ORC.

Problem

ValuesReader.skip(int n) ships with a naive default:

public void skip(int n) {
  for (int i = 0; i < n; i++) skip();
}

For dictionary-encoded columns (the common case), each skip() bottoms
out in RunLengthBitPackingHybridDecoder.readInt() — a mode switch,
array-index arithmetic, and a value the caller immediately discards.

Any filter-then-skip path (column-index row ranges, hash-join probe
filtering, runtime filters) pays this cost per skipped row.

Proposal

1. Add RunLengthBitPackingHybridDecoder.skipInts(int n) — re-use
   readNext() per run, then advance currentCount by
   min(n, currentCount) instead of walking every value through
   readInt().
2. Override skip(int) on DictionaryValuesReader and
   RunLengthBitPackingHybridValuesReader to call decoder.skipInts(n).

Component(s)

Core