[FEAT] connect: explain (WIP)

src/daft-connect/src/lib.rs

@@ -24,7 +24,7 @@ use spark_connect::{
 use tonic::{transport::Server, Request, Response, Status};
 use tracing::{debug, info};
 use uuid::Uuid;
-
+use spark_connect::analyze_plan_request::explain::ExplainMode;
 use crate::session::Session;
 
 mod config;
@@ -285,6 +285,8 @@ impl SparkConnectService for DaftSparkConnectService {
         use spark_connect::analyze_plan_request::*;
         let request = request.into_inner();
 
+        let mut session = self.get_session(&request.session_id)?;
+
         let AnalyzePlanRequest {
             session_id,
             analyze,
@@ -328,7 +330,35 @@ impl SparkConnectService for DaftSparkConnectService {
 
                 Ok(Response::new(response))
             }
-            _ => unimplemented_err!("Analyze plan operation is not yet implemented"),
+            Analyze::Explain(explain) => {
+                let Explain { plan, explain_mode } = explain;
+
+                let explain_mode = ExplainMode::try_from(explain_mode)
+                    .map_err(|_| invalid_argument_err!("Invalid Explain Mode"))?;
+
+                let Some(plan) = plan else {
+                    return invalid_argument_err!("Plan is required");
+                };
+
+                let Some(plan) = plan.op_type else {
+                    return invalid_argument_err!("Op Type is required");
+                };
+
+                let OpType::Root(relation) = plan else {
+                    return invalid_argument_err!("Plan operation is required");
+                };
+
+                let result = match session.handle_explain_command(relation, explain_mode).await {
+                    Ok(result) => result,
+                    Err(e) => return Err(Status::internal(format!("Error in Daft server: {e:?}"))),
+                };
+
+                Ok(Response::new(result))
+            }
+            op => {
+                println!("{op:#?}");
+                unimplemented_err!("Analyze plan operation is not yet implemented")
+            }
         }
     }
 

src/daft-connect/src/op.rs

@@ -1 +1,2 @@
 pub mod execute;
+pub mod analyze;

src/daft-connect/src/op/analyze.rs

@@ -0,0 +1,52 @@
+use std::pin::Pin;
+
+use spark_connect::{analyze_plan_response, AnalyzePlanResponse};
+
+pub type AnalyzeStream =
+    Pin<Box<dyn futures::Stream<Item = Result<AnalyzePlanResponse, Status>> + Send + Sync>>;
+
+use spark_connect::{analyze_plan_request::explain::ExplainMode, Relation};
+use tonic::Status;
+
+use crate::{session::Session, translation};
+
+pub struct PlanIds {
+    session: String,
+    server_side_session: String,
+}
+
+impl PlanIds {
+    pub fn response(&self, result: analyze_plan_response::Result) -> AnalyzePlanResponse {
+        AnalyzePlanResponse {
+            session_id: self.session.to_string(),
+            server_side_session_id: self.server_side_session.to_string(),
+            result: Some(result),
+        }
+    }
+}
+
+impl Session {
+    pub async fn handle_explain_command(
+        &self,
+        command: Relation,
+        _mode: ExplainMode,
+    ) -> eyre::Result<AnalyzePlanResponse> {
+        let context = PlanIds {
+            session: self.client_side_session_id().to_string(),
+            server_side_session: self.server_side_session_id().to_string(),
+        };
+
+        let plan = translation::to_logical_plan(command)?;
+        let optimized_plan = plan.optimize()?;
+
+        let optimized_plan = optimized_plan.build();
+
+        // todo: what do we want this to display
+        let explain_string = format!("{optimized_plan}");
+
+        let schema = analyze_plan_response::Explain { explain_string };
+
+        let response = context.response(analyze_plan_response::Result::Explain(schema));
+        Ok(response)
+    }
+}

src/daft-connect/src/op/execute.rs

@@ -14,7 +14,7 @@ mod root;
 
 pub type ExecuteStream = <DaftSparkConnectService as SparkConnectService>::ExecutePlanStream;
 
-pub struct PlanIds {
+struct PlanIds {
     session: String,
     server_side_session: String,
     operation: String,

tests/connect/test_explain.py

@@ -0,0 +1,16 @@
+from __future__ import annotations
+
+
+def test_explain(spark_session):
+    # Create ranges using Spark - with overlap
+    range1 = spark_session.range(7)  # Creates DataFrame with numbers 0 to 6
+    range2 = spark_session.range(3, 10)  # Creates DataFrame with numbers 3 to 9
+
+    # Union the two ranges
+    unioned = range1.union(range2)
+
+    # Get the explain plan
+    explain_str = unioned.explain(extended=True)
+
+    # Verify explain output contains expected elements
+    print(explain_str)