Fix Join Predicate Cleanup Bug in Route Merging (#16386)

Signed-off-by: Andres Taylor <andres@planetscale.com>
Signed-off-by: Florent Poinsard <florent.poinsard@outlook.fr>
Co-authored-by: Florent Poinsard <florent.poinsard@outlook.fr>

go/test/endtoend/vtgate/vitess_tester/join/join.test

@@ -0,0 +1,49 @@
+CREATE TABLE `t1`
+(
+    `id`   int unsigned NOT NULL AUTO_INCREMENT,
+    `name` varchar(191) NOT NULL,
+    PRIMARY KEY (`id`)
+) ENGINE InnoDB,
+  CHARSET utf8mb4,
+  COLLATE utf8mb4_unicode_ci;
+
+CREATE TABLE `t2`
+(
+    `id`    bigint unsigned NOT NULL AUTO_INCREMENT,
+    `t1_id` int unsigned NOT NULL,
+    PRIMARY KEY (`id`)
+) ENGINE InnoDB,
+  CHARSET utf8mb4,
+  COLLATE utf8mb4_unicode_ci;
+
+CREATE TABLE `t3`
+(
+    `id`   bigint unsigned NOT NULL AUTO_INCREMENT,
+    `name` varchar(191) NOT NULL,
+    PRIMARY KEY (`id`)
+) ENGINE InnoDB,
+  CHARSET utf8mb4,
+  COLLATE utf8mb4_unicode_ci;
+
+insert into t1 (id, name)
+values (1, 'A'),
+       (2, 'B'),
+       (3, 'C'),
+       (4, 'D');
+
+insert into t2 (id, t1_id)
+values (1, 1),
+       (2, 2),
+       (3, 3);
+
+insert into t3 (id, name)
+values (1, 'A'),
+       (2, 'B'),
+       (3, 'B'),
+       (4, 'B'),
+       (5, 'B');
+
+-- wait_authoritative t1
+-- wait_authoritative t2
+-- wait_authoritative t3
+select 42 from t1 join t2 on t1.id = t2.t1_id join t3 on t1.id = t3.id where t1.name or t2.id or t3.name;

go/test/endtoend/vtgate/vitess_tester/join/vschema.json

@@ -0,0 +1,38 @@
+{
+  "keyspaces": {
+    "joinks": {
+      "sharded": true,
+      "vindexes": {
+        "hash": {
+          "type": "hash"
+        }
+      },
+      "tables": {
+        "t1": {
+          "column_vindexes": [
+            {
+              "column": "id",
+              "name": "hash"
+            }
+          ]
+        },
+        "t2": {
+          "column_vindexes": [
+            {
+              "column": "t1_id",
+              "name": "hash"
+            }
+          ]
+        },
+        "t3": {
+          "column_vindexes": [
+            {
+              "column": "id",
+              "name": "hash"
+            }
+          ]
+        }
+      }
+    }
+  }
+}

go/vt/vtgate/planbuilder/operators/SQL_builder.go

@@ -233,7 +233,9 @@ func (qb *queryBuilder) joinWith(other *queryBuilder, onCondition sqlparser.Expr
 	switch joinType {
 	case sqlparser.NormalJoinType:
 		newFromClause = append(stmt.GetFrom(), otherStmt.GetFrom()...)
-		qb.addPredicate(onCondition)
+		for _, pred := range sqlparser.SplitAndExpression(nil, onCondition) {
+			qb.addPredicate(pred)
+		}
 	default:
 		newFromClause = []sqlparser.TableExpr{buildJoin(stmt, otherStmt, onCondition, joinType)}
 	}

go/vt/vtgate/planbuilder/testdata/from_cases.json

@@ -1783,6 +1783,30 @@
       ]
     }
   },
+  {
+    "comment": "three table join with join predicate touching all tables",
+    "query": "select 42 from user u join user_extra ue on u.id = ue.user_id join music m on m.user_id = u.id where u.foo or m.foo or ue.foo",
+    "plan": {
+      "QueryType": "SELECT",
+      "Original": "select 42 from user u join user_extra ue on u.id = ue.user_id join music m on m.user_id = u.id where u.foo or m.foo or ue.foo",
+      "Instructions": {
+        "OperatorType": "Route",
+        "Variant": "Scatter",
+        "Keyspace": {
+          "Name": "user",
+          "Sharded": true
+        },
+        "FieldQuery": "select 42 from `user` as u, user_extra as ue, music as m where 1 != 1",
+        "Query": "select 42 from `user` as u, user_extra as ue, music as m where u.id = ue.user_id and m.user_id = u.id and (u.foo or m.foo or ue.foo)",
+        "Table": "`user`, music, user_extra"
+      },
+      "TablesUsed": [
+        "user.music",
+        "user.user",
+        "user.user_extra"
+      ]
+    }
+  },
   {
     "comment": "join of normal table with information_schema",
     "query": "select unsharded.foo from unsharded join information_schema.CHARACTER_SETS",