[MCOL-5431] Remove dataset sorting from WFS. Created: 2023-02-21  Updated: 2023-07-01

Status: Open
Project: MariaDB ColumnStore
Component/s: ExeMgr, PrimProc
Affects Version/s: 22.08.7, 23.02.1
Fix Version/s: Icebox

Type: Bug Priority: Major
Reporter: Roman Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: beginner-friendly

Issue Links:
Problem/Incident
is caused by MCOL-5187 OOM happening when querying large dat... Stalled

 Description   

WFS is a separate step that also sorts result set replacing ORDER BY facility completely. After MCOL-3758 is done this doesn't make sense b/c sorting in WFS:

  • single-threaded
  • overlaps with sorting in TNS thus adds extra complexity introducing changes to sorting

There are two parts that must removed from these WFS methods to disable sorting in WFS:

  • WindowFunctionStep::initialize()
  • WindowFunctionStep::doPostProcessForSelect() runs a variant of merge sort routine

 Comments   
Comment by Debjyoti Ghosh [ 2023-02-22 ]

Hi, I want to contribute to solve this issue, can you please guide on how to get started with it?
I have build the server 11.0.1 code .

Comment by Roman [ 2023-02-24 ]

Hio Debjyoti. Feel free to find me in MariaDB zulip chat to discuss this.

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