[MDEV-10838] Avoiding computation when window frame is always empty Created: 2016-09-20  Updated: 2016-09-20

Status: Open
Project: MariaDB Server
Component/s: Optimizer - Window functions
Fix Version/s: None

Type: Task Priority: Major
Reporter: Vicențiu Ciorbaru Assignee: Vicențiu Ciorbaru
Resolution: Unresolved Votes: 0
Labels: None


 Description   

Currently we allow constructs such as:

[ROWS | RANGE] between N FOLLOWING and M FOLLOWING
 
where N > M

These constructs always lead to an empty frame. We correctly return results of NULL or 0 values for sum/window functions, however we perform a lot of unneeded IO operations. We can optimise this away by looking at frame definitions before starting computation.

 Comments   
Comment by Vicențiu Ciorbaru [ 2016-09-20 ]

CC: psergey, igor, sanja

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