zclllyybb opened a new issue, #48201: URL: https://github.com/apache/doris/issues/48201
New SQL functions are usually one of the most proper parts for newcomers to try to participate in Doris' development. For future reference, we'd like to list the basic processes for implementing a new function in Doris. ## What to Do To implement a new SQL function, here's what you need to write in your PR: 1. The function implementation and registration in BE 2. The function signature and visitor for nereids planner in FE 3. The constant fold implementation in FE if possible. just like what https://github.com/apache/doris/pull/40744/files did in `functions/executable/NumericArithmetic.java`. 4. A function docs PR in https://github.com/apache/doris-website must follow our newest docs specification. See https://github.com/apache/doris-website/pull/1992/files for an example. 5. Enough regression-test and BE-UT cases, referring files `test_template_{X}_arg(s).groovy` in https://github.com/apache/doris/pull/47307/files(maybe updated. So find the newest version in master branch) You could refer to https://github.com/apache/doris/pull/47307/files as a complete example( only missing FE constant folding) btw: You may see some PR modified `doris_builtin_functions.py`. Now we don't need it anymore. ## Key points ### BE implementations 1. Use the base template when you try to implement a date/arithmetic calculation. You can find them by searching for other similar functions. 2. Execution speed is very, very important for Doris. Therefore, you must eliminate all unnecessary copies and calculations. Try to use raw operations on inputs and outputs. If you can use the output Column's memory to receive the calculation result, do not add another variable and copy them. ### FE signature Most functions use one of the following interfaces: 1. `AlwaysNullable`: means the return type of the function is always wrapped in `Nullable`. Use it when the function may generate the `null` value for not-null input. 2. `AlwaysNotNullable`: means the return type of the function is never wrapped in `Nullable`. Use it when the function always changes the `null` input to a not-null output. 3. `PropagateNullable`: when the input columns contain at least one `Nullable` column, the output column is `Nullable`. otherwise not. When you just calculate the result for a not-null value and leave `null` alone, you need this. ### Testcase The testcases' type and quantities must not be less than the corresponding files in https://github.com/apache/doris/pull/47307/files. The data you use must cover all the borders of its datatype and other sensitive values. Add BE-UT case with `check_function_all_arg_comb` interface to cover Const-combinations. ## Other Advice 1. If you don't know how to use the proper interface of a certain type of object, just look for how others played with them. 2. The AI-assisted programming is quite mature now. So ask AI first if you want to make clear how some parts of the code work. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: commits-unsubscr...@doris.apache.org.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@doris.apache.org For additional commands, e-mail: commits-h...@doris.apache.org
