diesel-rs/diesel

Experiment with generate `allow_columns_to_appear_in_same_group_by_clause!` via `diesel print-schema`

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#2,555 创建于 2020年11月5日

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 (2 评论) (5 反应) (0 负责人)Rust (12,054 star) (1,003 fork)batch import
clidiscussion desiredgood first issuehelp wantedmentoring available

描述

#2549 introduced the allow_columns_to_appear_in_same_group_by_clause! macro that allows you to use more than one column in your group by clause. It opted not to generate a call to this macro for all columns in the schema via diesel print-schema due to compile time concerns. I would like to see some experimentation and some concert numbers for the actual compile time impact of this. As I think that's a good first issue, I will writeup some steps for someone willing to work on this:

  1. Similar to allow_tables_in_same_query! here we want to generate a call to allow_columns_to_appear_in_same_group_by_clause!. All required data are contained in self.tables. We need to iterate over all tables and all columns for each table and generate the corresponding macro call there.
  2. Test the impact on compile time of the generated schema.
    • That means get/generate a database with a large number of tables and columns (probably something that has >1000 columns or so).
    • Generate a schema.rs with the change in 1. applied
    • Generate a schema.rs without the change in 1. applied
    • Check and writedown the from scratch debug and release compile time for both variants. Also the incremental compile time without any change to the schema.rs module (but to some other module) may be interesting.
  3. Comment those numbers here, discuss if they are a acceptable hit

贡献者指南

技术栈
rust
领域
clidatabasetooling
议题类型
research
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。
3
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。
3-5 days
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。
clear
前置要求
basic Rust knowledgefamiliarity with diesel CLIcompile time benchmarking
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。
60
研究方向
The issue proposes generating a call to `allow columns to appear in same group by clause!` in `diesel print schema`. First, modify the code in `diesel cli/src/print schema.rs` (around line 158) to iterate over all tables and columns from `self.tables` and emit the macro call for each column. Second, create a database with many tables and columns (e.g., >1000 columns) to measure compile time impact. Generate `schema.rs` with and without the change, and record debug and release compile times, as well as incremental compile times. Finally, report the numbers and discuss acceptability.