From 1b1d936cb8b49a067989272904a056af5d57980c Mon Sep 17 00:00:00 2001
From: wshwsh12 <793703860@qq.com>
Date: Mon, 6 Dec 2021 11:06:45 +0800
Subject: [PATCH 1/2] fix

---
 executor/pipelined_window.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/executor/pipelined_window.go b/executor/pipelined_window.go
index 8e120376402be..7e8f6a0ed5c5e 100644
--- a/executor/pipelined_window.go
+++ b/executor/pipelined_window.go
@@ -179,7 +179,7 @@ func (e *PipelinedWindowExec) getRowsInPartition(ctx context.Context) (err error
 		var drained, samePartition bool
 		drained, err = e.fetchChild(ctx)
 		if err != nil {
-			err = errors.Trace(err)
+			return errors.Trace(err)
 		}
 		// we return immediately to use a combination of true newPartition but 0 in e.rowToConsume to indicate the data source is drained,
 		if drained {

From ce01dee7707a5b7014ea885e913224ce71a8b284 Mon Sep 17 00:00:00 2001
From: wshwsh12 <793703860@qq.com>
Date: Mon, 6 Dec 2021 11:53:49 +0800
Subject: [PATCH 2/2] add test

---
 expression/integration_test.go | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/expression/integration_test.go b/expression/integration_test.go
index 7f01c659c126d..61a72a9ce49f1 100644
--- a/expression/integration_test.go
+++ b/expression/integration_test.go
@@ -10669,3 +10669,15 @@ func (s *testIntegrationSuite) TestIssue30101(c *C) {
 	tk.MustExec("insert into t1 values(9223372036854775808, 9223372036854775809);")
 	tk.MustQuery("select greatest(c1, c2) from t1;").Sort().Check(testkit.Rows("9223372036854775809"))
 }
+
+func (s *testIntegrationSuite) TestIssue30326(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t;")
+	tk.MustExec("create table t(a int);")
+	tk.MustExec("insert into t values(1),(1),(2),(2);")
+	tk.MustExec("set tidb_window_concurrency = 1;")
+	err := tk.QueryToErr("select (FIRST_VALUE(1) over (partition by v.a)) as c3 from (select a from t where t.a = (select a from t t2 where t.a = t2.a)) as v;")
+	c.Assert(err, NotNil)
+	c.Assert(err.Error(), Equals, "[executor:1242]Subquery returns more than 1 row")
+}