Add function metadata ability to push down struct argument in optimizer

[kevintang2022]

Summary:
For some user defined functions, the pushdown subfield optimizer should transparently pass down utilized subfields of a struct type. The goal is to make the query plan look the same as if the udf was not being called on the struct. In order to accomplish this, the user defined function needs to take the struct argument passed into it, and unwrap it when converting an expression to a subfield.

Since there is no guarantee that the struct argument is always the first argument in the udf, the udf needs to specify which argument index to push down in its metadata.

T224244100

Presto version 0.293-20250521.210824-350

Differential Revision: D74738214

Test plan:
With this change, both of the queries below produce the same query plan after the table scan node rewrite

explain with shaped as (SELECT fb_reshape_row(person,CAST(NULL AS ROW(age INTEGER, city VARCHAR))) AS pcol FROM tangk_struct_table),
raw as (select person as pcol from tangk_struct_table)
select pcol.age from raw;

explain with shaped as (SELECT fb_reshape_row(person,CAST(NULL AS ROW(age INTEGER, city VARCHAR))) AS pcol FROM tangk_struct_table),
raw as (select person as pcol from tangk_struct_table)
select pcol.age from shaped;

0.293-20250517.231738-323 (pushdown subfields test version)
20250517_232920_00003_kcp7e correct query plan with pushed down subfield
20250517_233012_00005_kcp7e query plan with non relevant function
20250517_233034_00006_kcp7e expected plan

Verifier suite build: 20250521_205359_71488_cm4iz

pt suite build --predicate "lower(query) like '%fb_reshape_row%'" --suite atn_fb_reshape_row_subfields_udf --region atn --days 100

UDF only
https://www.internalfb.com/intern/presto/verifier/results/?test_id=223902
General
https://our.intern.facebook.com/intern/presto/verifier/results/?test_id=223903

[facebook-github-bot]

This pull request was exported from Phabricator. Differential Revision: D74738214

[rschlussel]

Looks good! Can you add a test? Maybe to TestHiveLogicalPlanner that the subfields are being pushed down and then a query correctness test (see TestLambdaSubfieldPruning for examples of tests for a related feature). You may have to register a function in the test that uses the new field you added (e.g. a passthrough function that takes a row and returns the row unchanged) to exercise your code.

[tdcmeehan]

This interface method, and the ones on ScalarFunction and SqlInvokedScalarFunction, are parameters to an annotation. Does a user implementing a function using the Presto SPI manually specify this value in the annotation? If not, then these should be removed.

[kevintang2022]

Yes they are specified in the annotation. If it is not specified, then it is -1 by default

Annotation looks like this

@CodegenScalarFunction(value = "function_name", calledOnNullInput = true, pushdownSubfieldArgIndex = 0)

[tdcmeehan]

Can you add some documentation on how this needs to be used to our documentation?

Also, why not add an annotation to the argument itself? Something like, @RowMayBeDereferenced. (BTW, can you give an example of how a function could know that this is safe to do?) You could annotate multiple of them, and we we could validate that the argument is, indeed, a struct to begin with.

Also, your example reference internal queries, can you add pastes of the explain plans?

[tdcmeehan]

Can you also add some tests?

[kevintang2022]

Instead of using annotation on the argument, I have chosen to pass the argindex in the codegen decorator because this allows it to be inside the FunctionMetadata.

I added some tests to TestHiveLogicalPlanner. One more change I will make is to perform some validation that the argIndex specified does correspond to a rowtype. And throw a warning when the code path is not reached due to invalid index

[steveburnett]

Suggest adding a release note, or a NO RELEASE NOTE block, as appropriate.