From 7cf22a72771f8dfc4ebc9cf76ddf0c93529e1e62 Mon Sep 17 00:00:00 2001
From: "vitess-bot[bot]" <108069721+vitess-bot[bot]@users.noreply.github.com>
Date: Mon, 8 Apr 2024 15:01:36 +0200
Subject: [PATCH] fix: don't forget DISTINCT for derived tables (#15672)

Signed-off-by: Andres Taylor <andres@planetscale.com>
---
 .../planbuilder/operators/SQL_builder.go      |  1 +
 .../planbuilder/testdata/from_cases.json      | 22 +++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/go/vt/vtgate/planbuilder/operators/SQL_builder.go b/go/vt/vtgate/planbuilder/operators/SQL_builder.go
index f6f934d4a3f..9eb27c6bed6 100644
--- a/go/vt/vtgate/planbuilder/operators/SQL_builder.go
+++ b/go/vt/vtgate/planbuilder/operators/SQL_builder.go
@@ -656,6 +656,7 @@ func buildDerivedSelect(op *Horizon, qb *queryBuilder, sel *sqlparser.Select) er
 	sel.GroupBy = opQuery.GroupBy
 	sel.Having = mergeHaving(sel.Having, opQuery.Having)
 	sel.SelectExprs = opQuery.SelectExprs
+	sel.Distinct = opQuery.Distinct
 	qb.addTableExpr(op.Alias, op.Alias, TableID(op), &sqlparser.DerivedTable{
 		Select: sel,
 	}, nil, op.ColumnAliases)
diff --git a/go/vt/vtgate/planbuilder/testdata/from_cases.json b/go/vt/vtgate/planbuilder/testdata/from_cases.json
index 567a3b5f254..6c977b04401 100644
--- a/go/vt/vtgate/planbuilder/testdata/from_cases.json
+++ b/go/vt/vtgate/planbuilder/testdata/from_cases.json
@@ -409,6 +409,28 @@
       ]
     }
   },
+  {
+    "comment": "DISTINCT inside derived table",
+    "query": "select * from (select distinct name from user) as t",
+    "plan": {
+      "QueryType": "SELECT",
+      "Original": "select * from (select distinct name from user) as t",
+      "Instructions": {
+        "OperatorType": "Route",
+        "Variant": "Scatter",
+        "Keyspace": {
+          "Name": "user",
+          "Sharded": true
+        },
+        "FieldQuery": "select `name` from (select `name` from `user` where 1 != 1) as t where 1 != 1",
+        "Query": "select `name` from (select distinct `name` from `user`) as t",
+        "Table": "`user`"
+      },
+      "TablesUsed": [
+        "user.user"
+      ]
+    }
+  },
   {
     "comment": "',' join unsharded",
     "query": "select u1.a, u2.a from unsharded u1, unsharded u2",