From fdab808589ba535ee7034215316d9b4ce6c033c5 Mon Sep 17 00:00:00 2001
From: Harshit Gangal <harshit@planetscale.com>
Date: Tue, 19 Sep 2023 18:26:19 +0530
Subject: [PATCH] fix: cost to include subshard opcode

Signed-off-by: Harshit Gangal <harshit@planetscale.com>
---
 .../planbuilder/operators/sharded_routing.go  |  2 +-
 .../planbuilder/testdata/from_cases.json      | 48 +++++++++++++++++++
 2 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/go/vt/vtgate/planbuilder/operators/sharded_routing.go b/go/vt/vtgate/planbuilder/operators/sharded_routing.go
index 13f28005ea8..a1babd90e32 100644
--- a/go/vt/vtgate/planbuilder/operators/sharded_routing.go
+++ b/go/vt/vtgate/planbuilder/operators/sharded_routing.go
@@ -327,7 +327,7 @@ func (tr *ShardedRouting) Cost() int {
 	switch tr.RouteOpCode {
 	case engine.EqualUnique:
 		return 1
-	case engine.Equal:
+	case engine.Equal, engine.SubShard:
 		return 5
 	case engine.IN:
 		return 10
diff --git a/go/vt/vtgate/planbuilder/testdata/from_cases.json b/go/vt/vtgate/planbuilder/testdata/from_cases.json
index efa04bfa7ca..805ce85dad9 100644
--- a/go/vt/vtgate/planbuilder/testdata/from_cases.json
+++ b/go/vt/vtgate/planbuilder/testdata/from_cases.json
@@ -4039,5 +4039,53 @@
         "main.unsharded_authoritative"
       ]
     }
+  },
+  {
+    "comment": "join query using table with muticolumn vindex",
+    "query": "select 1 from multicol_tbl m1 join multicol_tbl m2 on m1.cola = m2.cola",
+    "plan": {
+      "QueryType": "SELECT",
+      "Original": "select 1 from multicol_tbl m1 join multicol_tbl m2 on m1.cola = m2.cola",
+      "Instructions": {
+        "OperatorType": "Join",
+        "Variant": "Join",
+        "JoinColumnIndexes": "L:0",
+        "JoinVars": {
+          "m1_cola": 1
+        },
+        "TableName": "multicol_tbl_multicol_tbl",
+        "Inputs": [
+          {
+            "OperatorType": "Route",
+            "Variant": "Scatter",
+            "Keyspace": {
+              "Name": "user",
+              "Sharded": true
+            },
+            "FieldQuery": "select 1, m1.cola from multicol_tbl as m1 where 1 != 1",
+            "Query": "select 1, m1.cola from multicol_tbl as m1",
+            "Table": "multicol_tbl"
+          },
+          {
+            "OperatorType": "Route",
+            "Variant": "SubShard",
+            "Keyspace": {
+              "Name": "user",
+              "Sharded": true
+            },
+            "FieldQuery": "select 1 from multicol_tbl as m2 where 1 != 1",
+            "Query": "select 1 from multicol_tbl as m2 where m2.cola = :m1_cola",
+            "Table": "multicol_tbl",
+            "Values": [
+              ":m1_cola"
+            ],
+            "Vindex": "multicolIdx"
+          }
+        ]
+      },
+      "TablesUsed": [
+        "user.multicol_tbl"
+      ]
+    }
   }
 ]