[FEAT] connect: add df.limit and df.first (#3309)

src/daft-connect/src/translation/logical_plan.rs

@@ -1,6 +1,6 @@
 use daft_logical_plan::LogicalPlanBuilder;
 use eyre::{bail, Context};
-use spark_connect::{relation::RelType, Relation};
+use spark_connect::{relation::RelType, Limit, Relation};
 use tracing::warn;
 
 use crate::translation::logical_plan::{aggregate::aggregate, project::project, range::range};
@@ -19,6 +19,7 @@ pub fn to_logical_plan(relation: Relation) -> eyre::Result<LogicalPlanBuilder> {
     };
 
     match rel_type {
+        RelType::Limit(l) => limit(*l).wrap_err("Failed to apply limit to logical plan"),
         RelType::Range(r) => range(r).wrap_err("Failed to apply range to logical plan"),
         RelType::Project(p) => project(*p).wrap_err("Failed to apply project to logical plan"),
         RelType::Aggregate(a) => {
@@ -27,3 +28,15 @@ pub fn to_logical_plan(relation: Relation) -> eyre::Result<LogicalPlanBuilder> {
         plan => bail!("Unsupported relation type: {plan:?}"),
     }
 }
+
+fn limit(limit: Limit) -> eyre::Result<LogicalPlanBuilder> {
+    let Limit { input, limit } = limit;
+
+    let Some(input) = input else {
+        bail!("input must be set");
+    };
+
+    let plan = to_logical_plan(*input)?.limit(i64::from(limit), false)?; // todo: eager or no
+
+    Ok(plan)
+}

tests/connect/test_limit_simple.py

@@ -0,0 +1,14 @@
+from __future__ import annotations
+
+
+def test_range_first(spark_session):
+    spark_range = spark_session.range(10)
+    first_row = spark_range.first()
+    assert first_row["id"] == 0, "First row should have id=0"
+
+
+def test_range_limit(spark_session):
+    spark_range = spark_session.range(10)
+    limited_df = spark_range.limit(5).toPandas()
+    assert len(limited_df) == 5, "Limited DataFrame should have 5 rows"
+    assert list(limited_df["id"]) == list(range(5)), "Limited DataFrame should contain values 0-4"