[IMPALA-3905] Single-threaded scan node

• Type: Sub-task
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: Impala 2.6.0
• Fix Version/s: Impala 2.10.0
• Component/s: Backend
• Target Version: Product Backlog
• Assignee: Alexander Behm
• Reporter: Alexander Behm
• Created: 23/Jul/16 01:01
• Updated: 27/Jul/18 05:01
• Resolved: 02/Jul/17 04:34

Description

Since we will multi-thread query execution at the fragment level, we should rework our scan nodes and scanners to only use a single thread (the one that's executing the fragment).

Issue Links

• breaks: IMPALA-7360 Avro scanner sometimes skips blocks when skip marker is on HDFS block boundary
• is related to: IMPALA-7078 Selective Avro scans of wide tables use more memory than necessary
• is required by: IMPALA-5193 Impala reads gzip compressed text as binary when skip.header.line.count > 0