Use ANTLR DSL to parse expression

[MasamiYui]

Now DataSourceService#calculate use regexp and code logic for parse expression, if use ANTLR build dsl, maybe more suitable
Benefit:
1.Better performance with long expressions(Maybe)
2.Enable support for more flexible/complex expressions and function invoke at future
3.More security

Implement:
1.Complete the currently supported expression adaptation
2.Refer to promql for more features

[tomsun28]

+1 maybe we can have a try. DataSourceService#calculate not only for promql like this promql > 23 and promql < 43, also we can support SQL calculate like sql > 23 and xxx.

[MasamiYui]

sry, could you please describe it in more detail? I guess what you said QueryExecutor.execute supporting sql, and what i said before is replace regex + stack parse expression replace by antlr4, i am not sure which one you're talking about.

[tomsun28]

sry, could you please describe it in more detail? I guess what you said QueryExecutor.execute supporting sql, and what i said before is replace regex + stack parse expression replace by antlr4, i am not sure which one you're talking about.

hi sry for slow response, yes i said the implement of the antlr4 instread of regex+stack maybe need consider the impact of support QueryExecutor.execute supporting sql in the future. Theory should have no effect

[MasamiYui]

Collaborator

Thanks for your reply, I found that there is an empty implementation of SqlQueryExecutor in the code, i have two questions to ask:

1. When support sql query, the data source is still GreptimeDB or VictoriaMetrics? we need to convert the sql to promql?
2. Are there any other products with similar functions(support multiple language query)?

I don't know if anyone is doing this now, if not, I can try to make it.

[tomsun28]

hi, when switch sql query, the datasource maybe also gretimedb, beacuse it support sql query. If convert sql to promql, i think it's difficult and error prone. In the future, the usage scenario may be that the query for metrics data may be promql, and the query for log data may be sql. Both of these are supported in greptimedb.
2. Are there any other products with similar functions(support multiple language query)? This is not clear, maybe not.

[tomsun28]

Another thing is that we have to consider whether it is appropriate to support queries in multiple languages, or just one.

[bigcyy]

I will attempt to add expressions like sql > 23 and xxx, referring to the implementation in https://github.com/oceanbase/miniob/blob/main/src/observer/sql/parser/yacc_sql.y.