Merge pull request #49 from cmu-db/logical_optimizer_rules

feat: [Logical Optimizer]Eliminate Join Rule

Author: AveryQi115

Cargo.lock

@@ -8,6 +8,7 @@ edition = "2021"
 [dependencies]
 arrow-schema = "*"
 datafusion = "32.0.0"
+datafusion-expr = "32.0.0"
 async-trait = "0.1"
 optd-core = { path = "../optd-core" }
 optd-datafusion-repr = { path = "../optd-datafusion-repr" }

optd-datafusion-bridge/Cargo.toml

@@ -4,6 +4,7 @@ use datafusion::{
     logical_expr::{self, logical_plan, LogicalPlan, Operator},
     scalar::ScalarValue,
 };
+use datafusion_expr::Expr as DFExpr;
 use optd_core::rel_node::RelNode;
 use optd_datafusion_repr::plan_nodes::{
     BinOpExpr, BinOpType, ColumnRefExpr, ConstantExpr, Expr, ExprList, FuncExpr, FuncType,
@@ -117,7 +118,7 @@ impl OptdPlanContext<'_> {
                     expr,
                 )
                 .into_expr())
-            }
+            } 
             _ => bail!("Unsupported expression: {:?}", expr),
         }
     }
@@ -215,12 +216,33 @@ impl OptdPlanContext<'_> {
         }
 
         if log_ops.is_empty() {
-            Ok(LogicalJoin::new(
-                left,
-                right,
-                ConstantExpr::bool(true).into_expr(),
-                join_type,
-            ))
+            // optd currently only supports
+            // 1. normal equal condition join
+            //    select * from a join b on a.id = b.id
+            // 2. join on false/true
+            //    select * from a join b on false/true
+            // 3. join on other literals or other filters are not supported
+            //  instead of converting them to a join on true, we bail out
+
+            match node.filter {
+                Some(DFExpr::Literal(ScalarValue::Boolean(Some(val)))) => {
+                    return Ok(LogicalJoin::new(
+                        left,
+                        right,
+                        ConstantExpr::bool(val).into_expr(),
+                        join_type,
+                    ));
+                }
+                None => {
+                    return Ok(LogicalJoin::new(
+                        left,
+                        right,
+                        ConstantExpr::bool(true).into_expr(),
+                        join_type,
+                    ));
+                }
+                _ => bail!("unsupported join filter: {:?}", node.filter),
+            }
         } else if log_ops.len() == 1 {
             Ok(LogicalJoin::new(left, right, log_ops.remove(0), join_type))
         } else {

optd-datafusion-bridge/src/into_optd.rs

@@ -8,7 +8,8 @@ use optd_core::cascades::{CascadesOptimizer, GroupId, OptimizerProperties};
 use plan_nodes::{OptRelNode, OptRelNodeRef, OptRelNodeTyp, PlanNode};
 use properties::schema::{Catalog, SchemaPropertyBuilder};
 use rules::{
-    HashJoinRule, JoinAssocRule, JoinCommuteRule, PhysicalConversionRule, ProjectionPullUpJoin,
+    EliminateJoinRule, HashJoinRule, JoinAssocRule, JoinCommuteRule, PhysicalConversionRule,
+    ProjectionPullUpJoin,
 };
 
 pub use adaptive::PhysicalCollector;
@@ -46,6 +47,8 @@ impl DatafusionOptimizer {
         rules.push(Arc::new(JoinCommuteRule::new()));
         rules.push(Arc::new(JoinAssocRule::new()));
         rules.push(Arc::new(ProjectionPullUpJoin::new()));
+        rules.push(Arc::new(EliminateJoinRule::new()));
+
         let cost_model = AdaptiveCostModel::new(50);
         Self {
             runtime_statistics: cost_model.get_runtime_map(),

optd-datafusion-repr/src/lib.rs

@@ -4,5 +4,7 @@ mod macros;
 mod physical;
 
 // pub use filter_join::FilterJoinPullUpRule;
-pub use joins::{HashJoinRule, JoinAssocRule, JoinCommuteRule, ProjectionPullUpJoin};
+pub use joins::{
+    EliminateJoinRule, HashJoinRule, JoinAssocRule, JoinCommuteRule, ProjectionPullUpJoin,
+};
 pub use physical::PhysicalConversionRule;

optd-datafusion-repr/src/rules.rs

@@ -1,5 +1,6 @@
 use std::collections::HashMap;
 use std::sync::Arc;
+use std::vec;
 
 use itertools::Itertools;
 use optd_core::optimizer::Optimizer;
@@ -8,8 +9,9 @@ use optd_core::rules::{Rule, RuleMatcher};
 
 use super::macros::{define_impl_rule, define_rule};
 use crate::plan_nodes::{
-    BinOpExpr, BinOpType, ColumnRefExpr, Expr, ExprList, JoinType, LogicalJoin, LogicalProjection,
-    OptRelNode, OptRelNodeTyp, PhysicalHashJoin, PlanNode,
+    BinOpExpr, BinOpType, ColumnRefExpr, ConstantExpr, ConstantType, Expr, ExprList, JoinType,
+    LogicalEmptyRelation, LogicalJoin, LogicalProjection, OptRelNode, OptRelNodeTyp,
+    PhysicalHashJoin, PlanNode,
 };
 use crate::properties::schema::SchemaPropertyBuilder;
 
@@ -78,6 +80,44 @@ fn apply_join_commute(
     vec![node.as_ref().clone()]
 }
 
+define_rule!(
+    EliminateJoinRule,
+    apply_eliminate_join,
+    (Join(JoinType::Inner), left, right, [cond])
+);
+
+/// Eliminate logical join with constant predicates
+/// True predicates becomes CrossJoin (not yet implemented)
+/// False predicates become EmptyRelation (not yet implemented)
+#[allow(unused_variables)]
+fn apply_eliminate_join(
+    optimizer: &impl Optimizer<OptRelNodeTyp>,
+    EliminateJoinRulePicks { left, right, cond }: EliminateJoinRulePicks,
+) -> Vec<RelNode<OptRelNodeTyp>> {
+    if let OptRelNodeTyp::Constant(const_type) = cond.typ {
+        if const_type == ConstantType::Bool {
+            if let Some(data) = cond.data {
+                if data.as_bool() {
+                    // change it to cross join if filter is always true
+                    let node = LogicalJoin::new(
+                        PlanNode::from_group(left.into()),
+                        PlanNode::from_group(right.into()),
+                        ConstantExpr::bool(true).into_expr(),
+                        JoinType::Cross,
+                    );
+                    return vec![node.into_rel_node().as_ref().clone()];
+                } else {
+                    // No need to handle schema here, as all exprs in the same group
+                    // will have same logical properties
+                    let node = LogicalEmptyRelation::new(false);
+                    return vec![node.into_rel_node().as_ref().clone()];
+                }
+            }
+        }
+    }
+    vec![]
+}
+
 // (A join B) join C -> A join (B join C)
 define_rule!(
     JoinAssocRule,

optd-datafusion-repr/src/rules/joins.rs

@@ -33,44 +33,13 @@ PhysicalProjection
 -- Test whether the optimizer eliminates join to empty relation
 select * from t1 inner join t2 on false;
 select 64+1 from t1 inner join t2 on false;
-select 64+1 from t1 inner join t2 on 1=0;
 
 /*
 LogicalProjection { exprs: [ #0, #1, #2, #3 ] }
-└── LogicalJoin { join_type: Inner, cond: true }
+└── LogicalJoin { join_type: Inner, cond: false }
     ├── LogicalScan { table: t1 }
     └── LogicalScan { table: t2 }
 PhysicalProjection { exprs: [ #0, #1, #2, #3 ] }
-└── PhysicalProjection { exprs: [ #2, #3, #0, #1 ] }
-    └── PhysicalNestedLoopJoin { join_type: Inner, cond: true }
-        ├── PhysicalScan { table: t2 }
-        └── PhysicalScan { table: t1 }
-0 0 0 200
-0 0 1 201
-0 0 2 202
-1 1 0 200
-1 1 1 201
-1 1 2 202
-2 2 0 200
-2 2 1 201
-2 2 2 202
-65
-65
-65
-65
-65
-65
-65
-65
-65
-65
-65
-65
-65
-65
-65
-65
-65
-65
+└── PhysicalEmptyRelation { produce_one_row: false }
 */
 

optd-sqlplannertest/tests/empty_relation.planner.sql

@@ -15,7 +15,6 @@
 - sql: |
     select * from t1 inner join t2 on false;
     select 64+1 from t1 inner join t2 on false;
-    select 64+1 from t1 inner join t2 on 1=0;
   desc: Test whether the optimizer eliminates join to empty relation
   tasks:
     - explain:logical_optd,physical_optd