apache/pinot

Enhance the default column handling

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#8,699 opened on May 13, 2022

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help wanted

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Description

When new columns are added to a pinot table, the server is able to automatically generate default columns for the new added columns. There are 2 types of default column that can be auto-generated:

  1. New added column without transform function: default column will be filled with default null value (always dictionary encoded)
  2. New added column with transform function (derived column): default column will be filled with values calculated based on the transform function

There are 2 things not handled right now:

  1. Generate default column raw forward index (not dictionary encoded)
  2. Support transform function on another new added column: we need to calculate the dependency between new added columns, and generate them in sequence

See BaseDefaultColumnHandler for details

Contributor guide

Research direction
Study the BaseDefaultColumnHandler class to understand current default column generation logic. Focus on two missing features: (1) generating raw forward (non dictionary) indexes for new columns, and (2) handling dependencies when a transform function references another newly added column. Trace how columns are added and how default values are computed. Look for existing tests and run them to reproduce the issue.
Tech stack
java
Domain
databasedistributed systems
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
JavaApache Pinot basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30