From f027bed31a3bf112723e84dab7fd9d7ee10dd47d Mon Sep 17 00:00:00 2001
From: Andres Taylor <andres@planetscale.com>
Date: Fri, 22 Mar 2024 14:36:24 +0100
Subject: [PATCH] bugfix: fix handling of complex join predicates

Signed-off-by: Andres Taylor <andres@planetscale.com>
---
 .../planbuilder/operators/apply_join.go       | 12 ++++++----
 .../planbuilder/testdata/select_cases.json    | 24 +++++++++++++++++++
 2 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/go/vt/vtgate/planbuilder/operators/apply_join.go b/go/vt/vtgate/planbuilder/operators/apply_join.go
index 0bf03a1eb26..043e76b5e15 100644
--- a/go/vt/vtgate/planbuilder/operators/apply_join.go
+++ b/go/vt/vtgate/planbuilder/operators/apply_join.go
@@ -156,10 +156,14 @@ func (aj *ApplyJoin) AddJoinPredicate(ctx *plancontext.PlanningContext, expr sql
 	if expr == nil {
 		return
 	}
-	col := breakExpressionInLHSandRHSForApplyJoin(ctx, expr, TableID(aj.LHS))
-	aj.JoinPredicates.add(col)
-	ctx.AddJoinPredicates(expr, col.RHSExpr)
-	rhs := aj.RHS.AddPredicate(ctx, col.RHSExpr)
+	rhs := aj.RHS
+	predicates := sqlparser.SplitAndExpression(nil, expr)
+	for _, pred := range predicates {
+		col := breakExpressionInLHSandRHSForApplyJoin(ctx, pred, TableID(aj.LHS))
+		aj.JoinPredicates.add(col)
+		ctx.AddJoinPredicates(pred, col.RHSExpr)
+		rhs = rhs.AddPredicate(ctx, col.RHSExpr)
+	}
 	aj.RHS = rhs
 }
 
diff --git a/go/vt/vtgate/planbuilder/testdata/select_cases.json b/go/vt/vtgate/planbuilder/testdata/select_cases.json
index 63fba06202c..da96cbec0ec 100644
--- a/go/vt/vtgate/planbuilder/testdata/select_cases.json
+++ b/go/vt/vtgate/planbuilder/testdata/select_cases.json
@@ -2658,6 +2658,30 @@
       ]
     }
   },
+  {
+    "comment": "Complex join with multiple conditions merged into single route",
+    "query": "select 0 from user as u join user_extra as s on u.id = s.user_id join music as m on m.user_id = u.id and (s.foo or m.bar)",
+    "plan": {
+      "QueryType": "SELECT",
+      "Original": "select 0 from user as u join user_extra as s on u.id = s.user_id join music as m on m.user_id = u.id and (s.foo or m.bar)",
+      "Instructions": {
+        "OperatorType": "Route",
+        "Variant": "Scatter",
+        "Keyspace": {
+          "Name": "user",
+          "Sharded": true
+        },
+        "FieldQuery": "select 0 from `user` as u, user_extra as s, music as m where 1 != 1",
+        "Query": "select 0 from `user` as u, user_extra as s, music as m where u.id = s.user_id and m.user_id = u.id and (s.foo or m.bar)",
+        "Table": "`user`, music, user_extra"
+      },
+      "TablesUsed": [
+        "user.music",
+        "user.user",
+        "user.user_extra"
+      ]
+    }
+  },
   {
     "comment": "union as a derived table",
     "query": "select found from (select id as found from user union all (select id from unsharded)) as t",