From 1a113428c51ec4b5e8ffe7bb2f8a5f9d8be9519b Mon Sep 17 00:00:00 2001
From: Chao Wang <cclcwangchao@hotmail.com>
Date: Mon, 28 Mar 2022 18:28:51 +0800
Subject: [PATCH] executor: fix execute failed when table schema changed

---
 planner/core/cache.go      |  1 -
 server/driver_tidb.go      | 25 ++++++-----------------
 server/tidb_serial_test.go | 41 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 47 insertions(+), 20 deletions(-)

diff --git a/planner/core/cache.go b/planner/core/cache.go
index 05432bbe98599..1963652e3692b 100644
--- a/planner/core/cache.go
+++ b/planner/core/cache.go
@@ -215,7 +215,6 @@ type CachedPrepareStmt struct {
 	PreparedAst         *ast.Prepared
 	StmtDB              string // which DB the statement will be processed over
 	VisitInfos          []visitInfo
-	ColumnInfos         interface{}
 	Executor            interface{}
 	NormalizedSQL       string
 	NormalizedPlan      string
diff --git a/server/driver_tidb.go b/server/driver_tidb.go
index 3092b3b4df37c..2594f9a140b46 100644
--- a/server/driver_tidb.go
+++ b/server/driver_tidb.go
@@ -80,8 +80,7 @@ func (ts *TiDBStatement) Execute(ctx context.Context, args []types.Datum) (rs Re
 		return
 	}
 	rs = &tidbResultSet{
-		recordSet:    tidbRecordset,
-		preparedStmt: ts.ctx.GetSessionVars().PreparedStmts[ts.id].(*core.CachedPrepareStmt),
+		recordSet: tidbRecordset,
 	}
 	return
 }
@@ -302,11 +301,10 @@ func (tc *TiDBContext) GetStmtStats() *stmtstats.StatementStats {
 }
 
 type tidbResultSet struct {
-	recordSet    sqlexec.RecordSet
-	columns      []*ColumnInfo
-	rows         []chunk.Row
-	closed       int32
-	preparedStmt *core.CachedPrepareStmt
+	recordSet sqlexec.RecordSet
+	columns   []*ColumnInfo
+	rows      []chunk.Row
+	closed    int32
 }
 
 func (trs *tidbResultSet) NewChunk(alloc chunk.Allocator) *chunk.Chunk {
@@ -348,23 +346,12 @@ func (trs *tidbResultSet) Columns() []*ColumnInfo {
 	if trs.columns != nil {
 		return trs.columns
 	}
-	// for prepare statement, try to get cached columnInfo array
-	if trs.preparedStmt != nil {
-		ps := trs.preparedStmt
-		if colInfos, ok := ps.ColumnInfos.([]*ColumnInfo); ok {
-			trs.columns = colInfos
-		}
-	}
+
 	if trs.columns == nil {
 		fields := trs.recordSet.Fields()
 		for _, v := range fields {
 			trs.columns = append(trs.columns, convertColumnInfo(v))
 		}
-		if trs.preparedStmt != nil {
-			// if ColumnInfo struct has allocated object,
-			// here maybe we need deep copy ColumnInfo to do caching
-			trs.preparedStmt.ColumnInfos = trs.columns
-		}
 	}
 	return trs.columns
 }
diff --git a/server/tidb_serial_test.go b/server/tidb_serial_test.go
index 39907170ade80..468f840c888ee 100644
--- a/server/tidb_serial_test.go
+++ b/server/tidb_serial_test.go
@@ -348,6 +348,47 @@ func TestPrepareCount(t *testing.T) {
 	require.NoError(t, qctx.Close())
 }
 
+func TestPrepareExecute(t *testing.T) {
+	ts, cleanup := createTidbTestSuite(t)
+	defer cleanup()
+
+	qctx, err := ts.tidbdrv.OpenCtx(uint64(0), 0, uint8(tmysql.DefaultCollationID), "test", nil)
+	require.NoError(t, err)
+
+	ctx := context.Background()
+	_, err = qctx.Execute(ctx, "use test")
+	require.NoError(t, err)
+	_, err = qctx.Execute(ctx, "create table t1(id int primary key, v int)")
+	require.NoError(t, err)
+	_, err = qctx.Execute(ctx, "insert into t1 values(1, 100)")
+	require.NoError(t, err)
+
+	stmt, _, _, err := qctx.Prepare("select * from t1 where id=1")
+	require.NoError(t, err)
+	rs, err := stmt.Execute(ctx, nil)
+	require.NoError(t, err)
+	req := rs.NewChunk(nil)
+	require.NoError(t, rs.Next(ctx, req))
+	require.Equal(t, 2, req.NumCols())
+	require.Equal(t, req.NumCols(), len(rs.Columns()))
+	require.Equal(t, 1, req.NumRows())
+	require.Equal(t, int64(1), req.GetRow(0).GetInt64(0))
+	require.Equal(t, int64(100), req.GetRow(0).GetInt64(1))
+
+	// issue #33509
+	_, err = qctx.Execute(ctx, "alter table t1 drop column v")
+	require.NoError(t, err)
+
+	rs, err = stmt.Execute(ctx, nil)
+	require.NoError(t, err)
+	req = rs.NewChunk(nil)
+	require.NoError(t, rs.Next(ctx, req))
+	require.Equal(t, 1, req.NumCols())
+	require.Equal(t, req.NumCols(), len(rs.Columns()))
+	require.Equal(t, 1, req.NumRows())
+	require.Equal(t, int64(1), req.GetRow(0).GetInt64(0))
+}
+
 func TestDefaultCharacterAndCollation(t *testing.T) {
 	ts, cleanup := createTidbTestSuite(t)
 	defer cleanup()