Fix index plan for idiom param value (surrealdb#2865)

lib/src/idx/planner/tree.rs

@@ -4,7 +4,7 @@ use crate::err::Error;
 use crate::idx::planner::plan::{IndexOperator, IndexOption};
 use crate::sql::index::Index;
 use crate::sql::statements::DefineIndexStatement;
-use crate::sql::{Array, Cond, Expression, Idiom, Operator, Subquery, Table, Value, With};
+use crate::sql::{Array, Cond, Expression, Idiom, Operator, Part, Subquery, Table, Value, With};
 use async_recursion::async_recursion;
 use std::collections::HashMap;
 use std::sync::Arc;
@@ -126,6 +126,13 @@ impl<'a> TreeBuilder<'a> {
 	}
 
 	async fn eval_idiom(&mut self, i: &Idiom) -> Result<Node, Error> {
+		// Compute the idiom value if it is a param
+		if let Some(Part::Start(x)) = i.0.first() {
+			if x.is_param() {
+				let v = i.compute(self.ctx, self.opt, self.txn, None).await?;
+				return self.eval_value(&v).await;
+			}
+		}
 		if let Some(irs) = self.find_indexes(i).await? {
 			if !irs.is_empty() {
 				return Ok(Node::IndexedField(i.to_owned(), irs));

lib/src/sql/value/value.rs

@@ -991,6 +991,11 @@ impl Value {
 		}
 	}
 
+	/// Check if this Value is a Param
+	pub fn is_param(&self) -> bool {
+		matches!(self, Value::Param(_))
+	}
+
 	/// Check if this Value is a Geometry of a specific type
 	pub fn is_geometry_type(&self, types: &[String]) -> bool {
 		match self {

lib/tests/planner.rs

@@ -846,3 +846,43 @@ async fn select_index_single_range_operator_more_or_equal() -> Result<(), Error>
 async fn select_unique_single_range_operator_more_or_equal() -> Result<(), Error> {
 	select_single_range_operator(true, ">=", EXPLAIN_MORE_OR_EQUAL, RESULT_MORE_OR_EQUAL).await
 }
+
+#[tokio::test]
+async fn select_with_idiom_param_value() -> Result<(), Error> {
+	let dbs = new_ds().await?;
+	let ses = Session::owner().with_ns("test").with_db("test");
+	let sql = format!(
+		"
+		CREATE person:tobie SET name = 'Tobie', genre='m', company='SurrealDB';
+		CREATE person:jaime SET name = 'Jaime', genre='m', company='SurrealDB';
+		DEFINE INDEX name ON TABLE person COLUMNS name UNIQUE;
+		LET $name = 'Tobie';
+		LET $nameObj = {{name:'Tobie'}};
+		SELECT name FROM person WHERE name = $nameObj.name EXPLAIN;"
+	);
+	let mut res = dbs.execute(&sql, &ses, None).await?;
+	assert_eq!(res.len(), 6);
+	res.remove(0).result?;
+	res.remove(0).result?;
+	res.remove(0).result?;
+	res.remove(0).result?;
+	res.remove(0).result?;
+	let tmp = res.remove(0).result?;
+	let val = Value::parse(
+		r#"[
+				{
+					detail: {
+						plan: {
+							index: 'name',
+							operator: '=',
+							value: 'Tobie'
+						},
+						table: 'person'
+					},
+					operation: 'Iterate Index'
+				}
+			]"#,
+	);
+	assert_eq!(format!("{:#}", tmp), format!("{:#}", val));
+	Ok(())
+}