[IMPALA-3006] Impala may use incorrect bit order with BIT_PACKED encoding

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Won't Fix
• Affects Version/s: Impala 2.5.0
• Component/s: Backend
• Labels: correctness downgraded
• Target Version: Impala 3.0
• Assignee: Unassigned
• Reporter: Tim Armstrong
• Created: 16/Feb/16 20:11
• Updated: 15/Sep/17 21:18
• Resolved: 15/Sep/17 21:18

Description

Wes stated on IMPALA-3000:

It's unlikely Impala has ever seen this code path as all of its own Parquet data is encoded with the main RLE encoding – but conceivably there could be BIT_PACKED code floating around out there. But then there's a separate issue because BIT_PACKED uses MSB-ordered packing, while BitReader unpacks in LSB order (see the parquet-format). It may be worth disabling BIT_PACKED altogether if it is incorrect.

Issue Links

• is related to: IMPALA-5636 Impala writer claims that file uses BIT_PACKED encoding when it doesn't