From 921170ca89a4b094fecf5dc82e969fd507660535 Mon Sep 17 00:00:00 2001
From: Chao Wang <cclcwangchao@hotmail.com>
Date: Fri, 6 May 2022 18:29:52 +0800
Subject: [PATCH] Revert "executor: fix execute failed when table schema
 changed (#33519) (#33577)"

This reverts commit 4001a16db2ea52276b41301d1132a22e3932c9e7.
---
 planner/core/cache.go      |  1 +
 server/driver_tidb.go      | 25 +++++++++++++++++------
 server/tidb_serial_test.go | 41 --------------------------------------
 3 files changed, 20 insertions(+), 47 deletions(-)

diff --git a/planner/core/cache.go b/planner/core/cache.go
index ca0a1c6340b44..0d01f2bb98f73 100644
--- a/planner/core/cache.go
+++ b/planner/core/cache.go
@@ -208,6 +208,7 @@ func NewPlanCacheValue(plan Plan, names []*types.FieldName, srcMap map[*model.Ta
 type CachedPrepareStmt struct {
 	PreparedAst         *ast.Prepared
 	VisitInfos          []visitInfo
+	ColumnInfos         interface{}
 	Executor            interface{}
 	NormalizedSQL       string
 	NormalizedPlan      string
diff --git a/server/driver_tidb.go b/server/driver_tidb.go
index 677298c3c7fc4..6f3221cd21388 100644
--- a/server/driver_tidb.go
+++ b/server/driver_tidb.go
@@ -80,7 +80,8 @@ func (ts *TiDBStatement) Execute(ctx context.Context, args []types.Datum) (rs Re
 		return
 	}
 	rs = &tidbResultSet{
-		recordSet: tidbRecordset,
+		recordSet:    tidbRecordset,
+		preparedStmt: ts.ctx.GetSessionVars().PreparedStmts[ts.id].(*core.CachedPrepareStmt),
 	}
 	return
 }
@@ -296,10 +297,11 @@ func (tc *TiDBContext) GetStmtStats() *stmtstats.StatementStats {
 }
 
 type tidbResultSet struct {
-	recordSet sqlexec.RecordSet
-	columns   []*ColumnInfo
-	rows      []chunk.Row
-	closed    int32
+	recordSet    sqlexec.RecordSet
+	columns      []*ColumnInfo
+	rows         []chunk.Row
+	closed       int32
+	preparedStmt *core.CachedPrepareStmt
 }
 
 func (trs *tidbResultSet) NewChunk(alloc chunk.Allocator) *chunk.Chunk {
@@ -341,12 +343,23 @@ 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 141681e1df24e..5bbf88ad0e392 100644
--- a/server/tidb_serial_test.go
+++ b/server/tidb_serial_test.go
@@ -366,47 +366,6 @@ 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()