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feat: Add ConfigOptions to ScalarFunctionArgs #13527

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Omega359
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Which issue does this PR close?

Closes #13519

Rationale for this change

Allow udf's to access df config

What changes are included in this PR?

Code.

Are these changes tested?

Existing tests.

Are there any user-facing changes?

Not specifically, this is covered with the udf signature change in #13290

@github-actions github-actions bot added logical-expr Logical plan and expressions physical-expr Physical Expressions optimizer Optimizer rules core Core DataFusion crate common Related to common crate proto Related to proto crate functions labels Nov 22, 2024
@Omega359 Omega359 changed the title Feature/scalar func args session config feat: Add ConfigOptions to ScalarFuntionArgs Nov 22, 2024
@Omega359 Omega359 changed the title feat: Add ConfigOptions to ScalarFuntionArgs feat: Add ConfigOptions to ScalarFunctionArgs Nov 22, 2024
@Omega359
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There is a lot of file changes here but most of the important changes are in scalar_function.rs, There is a todo in expr_simplifier.rs that I would like feedback on.

@Omega359 Omega359 marked this pull request as ready for review November 22, 2024 16:42
@alamb
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alamb commented Nov 24, 2024

I plan to review this carefully tomorrow

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Thank you @Omega359 -- this is an epic plumbing exercise 🪠

The signature in ScalarFunctionArgs is 👌 very nice

This PR seems to require config_options to be cloned many times now. I wonder if it is possible to avoid that 🤔. I took a brief look and it seems to be somewhat challenging as SessionState allows mutable access to the underlying SessionConfig.

Maybe we could change the semantics so that SessionConfig has a Arc<ConfigOptions> which was cloned when it was modified (Arc::unwrap_or_clone() style) 🤔

I also think the const evaluator does need the actual correct ConfigOptions for correctness

let physical_expr =
datafusion_physical_expr::create_physical_expr(&expr, &df_schema, &props)?;
let config_options = Arc::new(ConfigOptions::default());
let physical_expr = datafusion_physical_expr::create_physical_expr(
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It seems somewhat inevitable that creating a physical expr will require the config options

However, I also think threading through the config options down through to the physical creation will (finally) permit people to pass things from the session down to function implementations (I think @cisaacson also was trying to do this in the past)

@@ -283,10 +284,16 @@ async fn prune_partitions(

// TODO: Plumb this down
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This todo may have now be complete

@@ -336,6 +337,8 @@ pub struct ScalarFunctionArgs<'a> {
// The return type of the scalar function returned (from `return_type` or `return_type_from_exprs`)
// when creating the physical expression from the logical expression
pub return_type: &'a DataType,
// The config options which can be used to lookup configuration properties
pub config_options: Arc<ConfigOptions>,
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🎉

Ok(e) => e,
Err(err) => return ConstSimplifyResult::SimplifyRuntimeError(err, expr),
};
// todo - should the config options be the actual options here or is this sufficient?
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I think the actual configuration options are needed here. Otherwise what will happen is that any function whose behavior relies on the ConfigOptions may have different behavior on columns and constants (or other expressions that can be constant folded)

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This PR seems to require config_options to be cloned many times now. I wonder if it is possible to avoid that 🤔. I took a brief look and it seems to be somewhat challenging as SessionState allows mutable access to the underlying SessionConfig.

Yes, it's a bit annoying. I was tempted to see if I could switch to &'a ConfigOptions everywhere. There is at least one 'real' (vs Arc::clone) clone for every query, possibly more as I haven't checked.

Maybe we could change the semantics so that SessionConfig has a Arc<ConfigOptions> which was cloned when it was modified (Arc::unwrap_or_clone() style) 🤔

Certainly possible, I can attempt that.

I also think the const evaluator does need the actual correct ConfigOptions for correctness

I was afraid of that. I was avoiding it because of the signature changes it would required just about everywhere which would cause even more headaches for those systems trying to upgrade.

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alamb commented Nov 25, 2024

Yeah, it is a tricky one for sure

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alamb commented Nov 27, 2024

Marking as draft as I think this PR is no longer waiting on feedback. Please mark it as ready for review when it is ready for another look

@alamb alamb marked this pull request as draft November 27, 2024 19:24
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Add SessionConfig reference to ScalarFunctionArgs
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