[PHOENIX-6412] Consider batching uncovered column merge for local indexes

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Duplicate
• Assignee: Unassigned
• Reporter: Lars Hofhansl
• Created: 15/Mar/21 16:09
• Updated: 21/Feb/24 05:54
• Resolved: 07/Jun/22 18:38

Description

Currently uncovered columns are merged row-by-row, performing a Get to the data region for each matching row in the index region.

Each Get needs to seek all the store scanners, and doing this per row is quite expensive.

Instead we could batch inside the RegionScannerFactory.getWrappedScanner() -> RegionScanner.nextRaw() method. Collect N index rows and then execute a single skip scan on the data region. 

I might be able to get to that, but there's someone who is interested in taking this up I would not mind

Issue Links

• duplicates: PHOENIX-6663 Use batching when joining data table rows with uncovered local index rows