pingcap/tidb

Support not null ScalarFunction.

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#9,965 opened on Mar 31, 2019

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help wanted

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Description

Feature Request

Describe the feature you'd like:

Currently, TiDB Don't have not null ScalarFunction, the implementation of not null is not (is null).

Separate implementation of not null must be better than the composed of two 2 ScalarFunction.

Next step: implement not null in TiKV coprocessor and push down.

Contributor guide

Research direction
Study how existing scalar functions like 'is null' are implemented in TiDB's expression framework. Implement a new 'not null' scalar function by following similar patterns. Then enable pushdown to TiKV coprocessor.
Tech stack
go
Domain
backenddatabase
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.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
GoGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65