build() function to return the database build info

[killme2008]

What problem does the new feature solve?

It's better to have an SQL function build that returns the database build info, for example:

mysql> select build()\G;

branch: develop
commit: fe2fc723bc19f37060b15625d363473f1f5bca10
version: 0.4.4

The result may be the same as greptime --version outputs.

greptimedb/src/common/version/src/lib.rs

Line 18 in 47e5154

pub fn setup_git_versions() {

What does the feature do?

An SQL function to return the database build info.

Implementation challenges

Learn how to write a function:

https://github.com/GreptimeTeam/greptimedb/blob/develop/src/common/function/src/scalars/math/rate.rs

[Dysprosium0626]

The idea maybe implement Function for something like BuildFunction and get info from build_data and register it in the FunctionRegistry. Then add something in the planner. Maybe I can have a try?

[killme2008]

The idea maybe implement Function for something like BuildFunction and get info from build_data and register it in the FunctionRegistry. Then add something in the planner. Maybe I can have a try?

Yes.

I think we can add a new mod system for these administrator functions.

Register functions refer to:

greptimedb/src/common/function/src/scalars/math.rs

Line 37 in 47e5154

impl MathFunction {

greptimedb/src/common/function/src/scalars/function_registry.rs

Line 76 in 47e5154

MathFunction::register(&function_registry);