[DRILL-4706] Fragment planning causes Drillbits to read remote chunks when local copies are available

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 1.6.0
• Component/s: Query Planning & Optimization
• Labels: performance planning

Environment

CentOS, RHEL

• Assignee: Unassigned
• Reporter: Kunal Khatua
• Created: 03/Jun/16 17:14
• Updated: 02/Aug/19 14:59

Description

When a table (datasize=70GB) of 160 parquet files (each having a single rowgroup and fitting within one chunk) is available on a 10-node setup with replication=3 ; a pure data scan query causes about 2% of the data to be read remotely.
Even with the creation of metadata cache, the planner is selecting a sub-optimal plan of executing the SCAN fragments such that some of the data is served from a remote server.

Issue Links

• links to: GitHub Pull Request #639
• links to: GitHub Pull Request #639