[PHOENIX-4232] Hide shadow cell and commit table access in TAL

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Labels: omid
• Assignee: Ohad Shaham
• Reporter: James R. Taylor
• Created: 25/Sep/17 20:00
• Updated: 08/Nov/17 12:35

Description

Omid needs to project the shadow cell column qualifier and then based on the value, filter the row. If the shadow cell is not found, it needs to perform a lookup in the commit table (the source of truth) to get the information instead. For the Phoenix integration, there are likely two TAL methods that can be added to handle this:

1. Add method call to new TAL method in preScannerOpen call on coprocessor that projects the shadow cell qualifiers and sets the time range. This is equivalent to the TransactionProcessor.preScannerOpen that Tephra does. It's possible this work could be done on the client side as well, but it's more likely that the stuff that Phoenix does may override this (but we could get it to work if need be).
2. Add TAL method that returns a RegionScanner to abstract out the filtering of the row (potentially querying commit table). This RegionScanner would be added as the first in the chain in the NonAggregateRegionScannerFactory.getRegionScanner() API.