pingcap/tidb

Support not null ScalarFunction.

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#9,965 创建于 2019年3月31日

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help wanted

描述

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.

贡献者指南

技术栈
go
领域
databasebackend
议题类型
feature
难度面向新贡献者的预计实现难度，1 表示很小改动，5 表示专家级工作。
4
预计时间有经验贡献者完成调查、实现、测试并准备 pull request 的粗略时间范围。
over 1 week
活动状态议题当前的可参与程度：新鲜、活跃、陈旧、阻塞或等待维护者输入。
stale
清晰度议题是否清楚说明期望改动、验收标准和下一步。
mostly clear
前置要求
Go programmingTiDB expression frameworkTiKV coprocessor basics
新手友好度1-100 的估计分数，表示该议题对首次贡献者的友好程度。
10
研究方向
Examine how existing scalar functions like `is null` and `not` are implemented in TiDB's expression package (e.g., `expression/scalar function.go`). Design a new `not null` scalar function that performs the inverse of `is null`. Then implement the function and ensure it supports coprocessor pushdown to TiKV. Review the TiKV coprocessor code for adding new scalar functions, following the pattern of existing implementations.
Support not null ScalarFunction. · pingcap/tidb#9965 | Good First Issue