[SERVER-58548] Support accumulator initializer expression in HashAgg Created: 14/Jul/21  Updated: 06/Dec/22  Resolved: 11/Oct/21

Status: Closed
Project: Core Server
Component/s: Query Execution
Affects Version/s: None
Fix Version/s: None

Type: Task Priority: Major - P3
Reporter: Eric Cox (Inactive) Assignee: Backlog - Query Execution
Resolution: Won't Fix Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Assigned Teams:
Query Execution
Participants:

 Description   

Each accumulator has an initializer expression that can be used to initialize an accumulator in certain scenarios. One example of this is when DSGroup creates a fresh group, and another is when DSGroup reads spilled accumulator states from disk and re-initializes groups.

We need a mechanism to initialize agg expressions in sbe. This could be done by augmenting HashAgg to evaluate an initializer expression.

We can think of other ways as well.



 Comments   
Comment by Ethan Zhang (Inactive) [ 11/Oct/21 ]

Spiling implementation will take care of this for us.

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