cherry pick #22568 to release-4.0 (#22641)

Signed-off-by: ti-srebot <[email protected]> Co-authored-by: Kenan Yao <[email protected]>
pingcap · Mar 1, 2021 · 66d97de · 66d97de
1 parent 17f20a7
commit 66d97de
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Showing 4 changed files with 55 additions and 8 deletions.
diff --git a/executor/builder.go b/executor/builder.go
@@ -1315,11 +1315,11 @@ func (b *executorBuilder) getSnapshotTS() (uint64, error) {
 	}
 
 	snapshotTS := b.ctx.GetSessionVars().SnapshotTS
-	txn, err := b.ctx.Txn(true)
-	if err != nil {
-		return 0, err
-	}
 	if snapshotTS == 0 {
+		txn, err := b.ctx.Txn(true)
+		if err != nil {
+			return 0, err
+		}
 		snapshotTS = txn.StartTS()
 	}
 	b.snapshotTS = snapshotTS

diff --git a/planner/core/cache.go b/planner/core/cache.go
@@ -67,7 +67,6 @@ type pstmtPlanCacheKey struct {
 	database             string
 	connID               uint64
 	pstmtID              uint32
-	snapshot             uint64
 	schemaVersion        int64
 	sqlMode              mysql.SQLMode
 	timezoneOffset       int
@@ -90,7 +89,6 @@ func (key *pstmtPlanCacheKey) Hash() []byte {
 		key.hash = append(key.hash, dbBytes...)
 		key.hash = codec.EncodeInt(key.hash, int64(key.connID))
 		key.hash = codec.EncodeInt(key.hash, int64(key.pstmtID))
-		key.hash = codec.EncodeInt(key.hash, int64(key.snapshot))
 		key.hash = codec.EncodeInt(key.hash, key.schemaVersion)
 		key.hash = codec.EncodeInt(key.hash, int64(key.sqlMode))
 		key.hash = codec.EncodeInt(key.hash, int64(key.timezoneOffset))
@@ -134,7 +132,6 @@ func NewPSTMTPlanCacheKey(sessionVars *variable.SessionVars, pstmtID uint32, sch
 		database:             sessionVars.CurrentDB,
 		connID:               sessionVars.ConnectionID,
 		pstmtID:              pstmtID,
-		snapshot:             sessionVars.SnapshotTS,
 		schemaVersion:        schemaVersion,
 		sqlMode:              sessionVars.SQLMode,
 		timezoneOffset:       timezoneOffset,

diff --git a/planner/core/cache_test.go b/planner/core/cache_test.go
@@ -39,5 +39,5 @@ func (s *testCacheSuite) SetUpSuite(c *C) {
 func (s *testCacheSuite) TestCacheKey(c *C) {
 	defer testleak.AfterTest(c)()
 	key := NewPSTMTPlanCacheKey(s.ctx.GetSessionVars(), 1, 1)
-	c.Assert(key.Hash(), DeepEquals, []byte{0x74, 0x65, 0x73, 0x74, 0x80, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x80, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x1, 0x80, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x80, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x1, 0x80, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x80, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x74, 0x69, 0x64, 0x62, 0x74, 0x69, 0x6b, 0x76, 0x74, 0x69, 0x66, 0x6c, 0x61, 0x73, 0x68})
+	c.Assert(key.Hash(), DeepEquals, []byte{0x74, 0x65, 0x73, 0x74, 0x80, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x80, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x1, 0x80, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x1, 0x80, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x80, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x74, 0x69, 0x64, 0x62, 0x74, 0x69, 0x6b, 0x76, 0x74, 0x69, 0x66, 0x6c, 0x61, 0x73, 0x68})
 }
diff --git a/planner/core/prepare_test.go b/planner/core/prepare_test.go
@@ -893,3 +893,53 @@ func (s *testPrepareSerialSuite) TestPrepareCacheWithJoinTable(c *C) {
 	tk.MustQuery("execute stmt using @a").Check(testkit.Rows())
 	tk.MustQuery("execute stmt using @b").Check(testkit.Rows("a <nil> <nil>"))
 }
+
+func (s *testPlanSerialSuite) TestPlanCacheSnapshot(c *C) {
+	store, _, err := newStoreWithBootstrap()
+	c.Assert(err, IsNil)
+	tk := testkit.NewTestKit(c, store)
+	orgEnable := core.PreparedPlanCacheEnabled()
+	defer func() {
+		store.Close()
+		core.SetPreparedPlanCache(orgEnable)
+	}()
+	core.SetPreparedPlanCache(true)
+
+	tk.Se, err = session.CreateSession4TestWithOpt(store, &session.Opt{
+		PreparedPlanCache: kvcache.NewSimpleLRUCache(100, 0.1, math.MaxUint64),
+	})
+	c.Assert(err, IsNil)
+
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t(id int)")
+	tk.MustExec("insert into t values (1),(2),(3),(4)")
+
+	// For mocktikv, safe point is not initialized, we manually insert it for snapshot to use.
+	timeSafe := time.Now().Add(-48 * 60 * 60 * time.Second).Format("20060102-15:04:05 -0700 MST")
+	safePointSQL := `INSERT HIGH_PRIORITY INTO mysql.tidb VALUES ('tikv_gc_safe_point', '%[1]s', '')
+			       ON DUPLICATE KEY
+			       UPDATE variable_value = '%[1]s'`
+	tk.MustExec(fmt.Sprintf(safePointSQL, timeSafe))
+
+	tk.MustExec("prepare stmt from 'select * from t where id=?'")
+	tk.MustExec("set @p = 1")
+	tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("0"))
+	tk.MustQuery("execute stmt using @p").Check(testkit.Rows("1"))
+	tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("0"))
+	tk.MustQuery("execute stmt using @p").Check(testkit.Rows("1"))
+	tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("1"))
+
+	// Record the current tso.
+	tk.MustExec("begin")
+	tso := tk.Se.GetSessionVars().TxnCtx.StartTS
+	tk.MustExec("rollback")
+	c.Assert(tso > 0, IsTrue)
+	// Insert one more row with id = 1.
+	tk.MustExec("insert into t values (1)")
+
+	tk.MustExec(fmt.Sprintf("set @@tidb_snapshot = '%d'", tso))
+	tk.MustQuery("select * from t where id = 1").Check(testkit.Rows("1"))
+	tk.MustQuery("execute stmt using @p").Check(testkit.Rows("1"))
+	tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("1"))
+}