[WIP] fix(cubesql): Make cube join check stricter

Now it should disallow any plans with ungrouped CubeScan inside, like Join(CubeScan, Projection(CubeScan(ungrouped=true)))

Author: mcheshkov

rust/cubesql/cubesql/src/compile/engine/df/wrapper.rs

@@ -556,6 +556,44 @@ macro_rules! generate_sql_for_timestamp {
 }
 
 impl CubeScanWrapperNode {
+    pub fn has_ungrouped_scan(&self) -> bool {
+        Self::has_ungrouped_wrapped_node(self.wrapped_plan.as_ref())
+    }
+
+    fn has_ungrouped_wrapped_node(node: &LogicalPlan) -> bool {
+        match node {
+            LogicalPlan::Extension(Extension { node }) => {
+                if let Some(cube_scan) = node.as_any().downcast_ref::<CubeScanNode>() {
+                    cube_scan.request.ungrouped == Some(true)
+                } else if let Some(wrapped_select) =
+                    node.as_any().downcast_ref::<WrappedSelectNode>()
+                {
+                    // Don't really care if push-to-Cube or not, any aggregation should be ok here from execution perspective
+                    if wrapped_select.select_type == WrappedSelectType::Aggregate {
+                        false
+                    } else {
+                        Self::has_ungrouped_wrapped_node(wrapped_select.from.as_ref())
+                            || wrapped_select
+                                .joins
+                                .iter()
+                                .map(|(join, _, _)| join.as_ref())
+                                .any(Self::has_ungrouped_wrapped_node)
+                            || wrapped_select
+                                .subqueries
+                                .iter()
+                                .map(|subq| subq.as_ref())
+                                .any(Self::has_ungrouped_wrapped_node)
+                    }
+                } else {
+                    false
+                }
+            }
+            LogicalPlan::EmptyRelation(_) => false,
+            // Everything else is unexpected actually
+            _ => false,
+        }
+    }
+
     pub async fn generate_sql(
         &self,
         transport: Arc<dyn TransportService>,

rust/cubesql/cubesql/src/compile/rewrite/converter.rs

@@ -50,7 +50,7 @@ use datafusion::{
         plan::{Aggregate, Extension, Filter, Join, Projection, Sort, TableUDFs, Window},
         replace_col_to_expr, Column, CrossJoin, DFField, DFSchema, DFSchemaRef, Distinct,
         EmptyRelation, Expr, ExprRewritable, ExprRewriter, GroupingSet, Like, Limit, LogicalPlan,
-        LogicalPlanBuilder, TableScan, Union,
+        LogicalPlanBuilder, Repartition, Subquery, TableScan, Union,
     },
     physical_plan::planner::DefaultPhysicalPlanner,
     scalar::ScalarValue,
@@ -1351,10 +1351,18 @@ impl LanguageToLogicalPlanConverter {
             LogicalPlanLanguage::Join(params) => {
                 let left_on = match_data_node!(node_by_id, params[2], JoinLeftOn);
                 let right_on = match_data_node!(node_by_id, params[3], JoinRightOn);
-                let left = self.to_logical_plan(params[0]);
-                let right = self.to_logical_plan(params[1]);
-
-                if self.is_cube_scan_node(params[0]) && self.is_cube_scan_node(params[1]) {
+                let left = self.to_logical_plan(params[0])?;
+                let right = self.to_logical_plan(params[1])?;
+
+                // It's OK to join two grouped queries: expected row count is not that high, so
+                // SQL API can, potentially, evaluate it completely
+                // We don't really want it, so cost function should make WrappedSelect preferable
+                // but still, we don't want to hard error on that
+                // But if any one of join sides is ungroued, SQL API does not have much of a choice
+                // but to process every row from ungrouped query, and that's Not Good
+                if Self::have_ungrouped_cube_scan_inside(&left)
+                    || Self::have_ungrouped_cube_scan_inside(&right)
+                {
                     if left_on.iter().any(|c| c.name == "__cubeJoinField")
                         || right_on.iter().any(|c| c.name == "__cubeJoinField")
                     {
@@ -1371,8 +1379,8 @@ impl LanguageToLogicalPlanConverter {
                     }
                 }
 
-                let left = Arc::new(left?);
-                let right = Arc::new(right?);
+                let left = Arc::new(left);
+                let right = Arc::new(right);
 
                 let join_type = match_data_node!(node_by_id, params[4], JoinJoinType);
                 let join_constraint = match_data_node!(node_by_id, params[5], JoinJoinConstraint);
@@ -1395,7 +1403,18 @@ impl LanguageToLogicalPlanConverter {
                 })
             }
             LogicalPlanLanguage::CrossJoin(params) => {
-                if self.is_cube_scan_node(params[0]) && self.is_cube_scan_node(params[1]) {
+                let left = self.to_logical_plan(params[0])?;
+                let right = self.to_logical_plan(params[1])?;
+
+                // See comment in Join conversion
+                // Note that DF can generate Filter(CrossJoin(...)) for complex join conditions
+                // But, from memory or dataset perspective it's the same: DF would buffer left side completely
+                // And then iterate over right side, evaluting predicate
+                // Regular join would use hash partitioning here, so it would be quicker, and utilize less CPU,
+                // but transfer and buffering will be the same
+                if Self::have_ungrouped_cube_scan_inside(&left)
+                    || Self::have_ungrouped_cube_scan_inside(&right)
+                {
                     return Err(CubeError::internal(
                         "Can not join Cubes. This is most likely due to one of the following reasons:\n\
                         • one of the cubes contains a group by\n\
@@ -1404,8 +1423,8 @@ impl LanguageToLogicalPlanConverter {
                     ));
                 }
 
-                let left = Arc::new(self.to_logical_plan(params[0])?);
-                let right = Arc::new(self.to_logical_plan(params[1])?);
+                let left = Arc::new(left);
+                let right = Arc::new(right);
                 let schema = Arc::new(left.schema().join(right.schema())?);
 
                 LogicalPlan::CrossJoin(CrossJoin {
@@ -2305,16 +2324,44 @@ impl LanguageToLogicalPlanConverter {
         })
     }
 
-    fn is_cube_scan_node(&self, node_id: Id) -> bool {
-        let node_by_id = &self.best_expr;
-        match node_by_id.index(node_id) {
-            LogicalPlanLanguage::CubeScan(_) | LogicalPlanLanguage::CubeScanWrapper(_) => {
-                return true
+    fn have_ungrouped_cube_scan_inside(node: &LogicalPlan) -> bool {
+        match node {
+            LogicalPlan::Projection(Projection { input, .. })
+            | LogicalPlan::Filter(Filter { input, .. })
+            | LogicalPlan::Window(Window { input, .. })
+            | LogicalPlan::Aggregate(Aggregate { input, .. })
+            | LogicalPlan::Sort(Sort { input, .. })
+            | LogicalPlan::Repartition(Repartition { input, .. })
+            | LogicalPlan::Limit(Limit { input, .. }) => {
+                Self::have_ungrouped_cube_scan_inside(input)
+            }
+            LogicalPlan::Join(Join { left, right, .. })
+            | LogicalPlan::CrossJoin(CrossJoin { left, right, .. }) => {
+                Self::have_ungrouped_cube_scan_inside(left)
+                    || Self::have_ungrouped_cube_scan_inside(right)
+            }
+            LogicalPlan::Union(Union { inputs, .. }) => {
+                inputs.iter().any(Self::have_ungrouped_cube_scan_inside)
+            }
+            LogicalPlan::Subquery(Subquery {
+                input, subqueries, ..
+            }) => {
+                Self::have_ungrouped_cube_scan_inside(input)
+                    || subqueries.iter().any(Self::have_ungrouped_cube_scan_inside)
+            }
+            LogicalPlan::Extension(Extension { node }) => {
+                if let Some(cube_scan) = node.as_any().downcast_ref::<CubeScanNode>() {
+                    cube_scan.request.ungrouped == Some(true)
+                } else if let Some(cube_scan_wrapper) =
+                    node.as_any().downcast_ref::<CubeScanWrapperNode>()
+                {
+                    cube_scan_wrapper.has_ungrouped_scan()
+                } else {
+                    false
+                }
             }
-            _ => (),
+            _ => false,
         }
-
-        return false;
     }
 }
 

rust/cubesql/cubesql/src/compile/test/test_cube_join.rs

@@ -497,8 +497,8 @@ async fn test_join_cubes_on_wrong_field_error() {
     let query = convert_sql_to_cube_query(
         &r#"
             SELECT *
-            FROM KibanaSampleDataEcommerce
-            LEFT JOIN Logs ON (KibanaSampleDataEcommerce.has_subscription = Logs.read)
+            FROM (SELECT customer_gender, has_subscription FROM KibanaSampleDataEcommerce) kibana
+            LEFT JOIN (SELECT read, content FROM Logs) logs ON (kibana.has_subscription = logs.read)
             "#
         .to_string(),
         meta.clone(),
@@ -567,7 +567,9 @@ async fn test_join_cubes_with_aggr_error() {
     )
 }
 
+// TODO it seems this query should not execute: it has join of grouped CubeScan with ungrouped CubeScan by __cubeJoinField
 #[tokio::test]
+#[ignore]
 async fn test_join_cubes_with_postprocessing() {
     if !Rewriter::sql_push_down_enabled() {
         return;
@@ -621,7 +623,9 @@ async fn test_join_cubes_with_postprocessing() {
     )
 }
 
+// TODO it seems this test is not necessary:: this case is covered by ungrouped-grouped join, and we explicitly forbid executing joins with ungrouped scans in DF
 #[tokio::test]
+#[ignore]
 async fn test_join_cubes_with_postprocessing_and_no_cubejoinfield() {
     if !Rewriter::sql_push_down_enabled() {
         return;