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planner: fix wrong prepare plan after isolation read changed (pingcap…
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…#16293) (pingcap#17570)

* cherry pick pingcap#16293 to release-4.0

Signed-off-by: sre-bot <sre-bot@pingcap.com>

* fix fmt

Co-authored-by: Zhuomin(Charming) Liu <lzmhhh123@gmail.com>
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@sre-bot @lzmhhh123
sre-bot and lzmhhh123 authored Jun 6, 2020
1 parent 3ab93c0 commit be97b46
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Showing 4 changed files with 90 additions and 21 deletions.
49 changes: 49 additions & 0 deletions executor/prepared_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,14 @@
package executor_test

import (
"fmt"

. "github.com/pingcap/check"
"github.com/pingcap/parser/auth"
"github.com/pingcap/parser/model"
"github.com/pingcap/tidb/domain"
plannercore "github.com/pingcap/tidb/planner/core"
"github.com/pingcap/tidb/util"
"github.com/pingcap/tidb/util/testkit"
)

Expand Down Expand Up @@ -53,3 +60,45 @@ func (s *testSuite1) TestIgnorePlanCache(c *C) {
tk.MustExec("execute stmt using @ignore_plan_doma")
c.Assert(tk.Se.GetSessionVars().StmtCtx.UseCache, IsFalse)
}

func (s *testSuite1) TestPrepareStmtAfterIsolationReadChange(c *C) {
tk := testkit.NewTestKitWithInit(c, s.store)
tk.Se.Auth(&auth.UserIdentity{Username: "root", Hostname: "localhost", CurrentUser: true, AuthUsername: "root", AuthHostname: "%"}, nil, []byte("012345678901234567890"))

tk.MustExec("drop table if exists t")
tk.MustExec("create table t(a int)")
// create virtual tiflash replica.
dom := domain.GetDomain(tk.Se)
is := dom.InfoSchema()
db, exists := is.SchemaByName(model.NewCIStr("test"))
c.Assert(exists, IsTrue)
for _, tblInfo := range db.Tables {
if tblInfo.Name.L == "t" {
tblInfo.TiFlashReplica = &model.TiFlashReplicaInfo{
Count: 1,
Available: true,
}
}
}

tk.MustExec("set @@session.tidb_isolation_read_engines='tikv'")
tk.MustExec("prepare stmt from \"select * from t\"")
tk.MustQuery("execute stmt")
tkProcess := tk.Se.ShowProcess()
ps := []*util.ProcessInfo{tkProcess}
tk.Se.SetSessionManager(&mockSessionManager1{PS: ps})
rows := tk.MustQuery(fmt.Sprintf("explain for connection %d", tkProcess.ID)).Rows()
c.Assert(rows[len(rows)-1][2], Equals, "cop[tikv]")

tk.MustExec("set @@session.tidb_isolation_read_engines='tiflash'")
tk.MustExec("execute stmt")
tkProcess = tk.Se.ShowProcess()
ps = []*util.ProcessInfo{tkProcess}
tk.Se.SetSessionManager(&mockSessionManager1{PS: ps})
rows = tk.MustQuery(fmt.Sprintf("explain for connection %d", tkProcess.ID)).Rows()
c.Assert(rows[len(rows)-1][2], Equals, "cop[tiflash]")

c.Assert(len(tk.Se.GetSessionVars().PreparedStmts), Equals, 1)
c.Assert(tk.Se.GetSessionVars().PreparedStmts[1].(*plannercore.CachedPrepareStmt).NormalizedSQL, Equals, "select * from t")
c.Assert(tk.Se.GetSessionVars().PreparedStmts[1].(*plannercore.CachedPrepareStmt).NormalizedPlan, Equals, "")
}
58 changes: 39 additions & 19 deletions planner/core/cache.go
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@ import (
"github.com/pingcap/parser/ast"
"github.com/pingcap/parser/model"
"github.com/pingcap/parser/mysql"
"github.com/pingcap/tidb/kv"
"github.com/pingcap/tidb/sessionctx/variable"
"github.com/pingcap/tidb/types"
"github.com/pingcap/tidb/util/codec"
Expand Down Expand Up @@ -63,14 +64,15 @@ func PreparedPlanCacheEnabled() bool {
}

type pstmtPlanCacheKey struct {
database string
connID uint64
pstmtID uint32
snapshot uint64
schemaVersion int64
sqlMode mysql.SQLMode
timezoneOffset int
selectLimit uint64
database string
connID uint64
pstmtID uint32
snapshot uint64
schemaVersion int64
sqlMode mysql.SQLMode
timezoneOffset int
selectLimit uint64
isolationReadEngines map[kv.StoreType]struct{}

hash []byte
}
Expand All @@ -80,7 +82,7 @@ func (key *pstmtPlanCacheKey) Hash() []byte {
if len(key.hash) == 0 {
var (
dbBytes = hack.Slice(key.database)
bufferSize = len(dbBytes) + 8*6
bufferSize = len(dbBytes) + 8*6 + 3*8
)
if key.hash == nil {
key.hash = make([]byte, 0, bufferSize)
Expand All @@ -93,19 +95,32 @@ func (key *pstmtPlanCacheKey) Hash() []byte {
key.hash = codec.EncodeInt(key.hash, int64(key.sqlMode))
key.hash = codec.EncodeInt(key.hash, int64(key.timezoneOffset))
key.hash = codec.EncodeInt(key.hash, int64(key.selectLimit))
if _, ok := key.isolationReadEngines[kv.TiDB]; ok {
key.hash = append(key.hash, kv.TiDB.Name()...)
}
if _, ok := key.isolationReadEngines[kv.TiKV]; ok {
key.hash = append(key.hash, kv.TiKV.Name()...)
}
if _, ok := key.isolationReadEngines[kv.TiFlash]; ok {
key.hash = append(key.hash, kv.TiFlash.Name()...)
}
}
return key.hash
}

// SetPstmtIDSchemaVersion implements PstmtCacheKeyMutator interface to change pstmtID and schemaVersion of cacheKey.
// so we can reuse Key instead of new every time.
func SetPstmtIDSchemaVersion(key kvcache.Key, pstmtID uint32, schemaVersion int64) {
func SetPstmtIDSchemaVersion(key kvcache.Key, pstmtID uint32, schemaVersion int64, isolationReadEngines map[kv.StoreType]struct{}) {
psStmtKey, isPsStmtKey := key.(*pstmtPlanCacheKey)
if !isPsStmtKey {
return
}
psStmtKey.pstmtID = pstmtID
psStmtKey.schemaVersion = schemaVersion
psStmtKey.isolationReadEngines = make(map[kv.StoreType]struct{})
for k, v := range isolationReadEngines {
psStmtKey.isolationReadEngines[k] = v
}
psStmtKey.hash = psStmtKey.hash[:0]
}

Expand All @@ -115,16 +130,21 @@ func NewPSTMTPlanCacheKey(sessionVars *variable.SessionVars, pstmtID uint32, sch
if sessionVars.TimeZone != nil {
_, timezoneOffset = time.Now().In(sessionVars.TimeZone).Zone()
}
return &pstmtPlanCacheKey{
database: sessionVars.CurrentDB,
connID: sessionVars.ConnectionID,
pstmtID: pstmtID,
snapshot: sessionVars.SnapshotTS,
schemaVersion: schemaVersion,
sqlMode: sessionVars.SQLMode,
timezoneOffset: timezoneOffset,
selectLimit: sessionVars.SelectLimit,
key := &pstmtPlanCacheKey{
database: sessionVars.CurrentDB,
connID: sessionVars.ConnectionID,
pstmtID: pstmtID,
snapshot: sessionVars.SnapshotTS,
schemaVersion: schemaVersion,
sqlMode: sessionVars.SQLMode,
timezoneOffset: timezoneOffset,
selectLimit: sessionVars.SelectLimit,
isolationReadEngines: make(map[kv.StoreType]struct{}),
}
for k, v := range sessionVars.IsolationReadEngines {
key.isolationReadEngines[k] = v
}
return key
}

// PSTMTPlanCacheValue stores the cached Statement and StmtNode.
Expand Down
2 changes: 1 addition & 1 deletion planner/core/cache_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -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})
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})
}
2 changes: 1 addition & 1 deletion session/session.go
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Original file line number Diff line number Diff line change
Expand Up @@ -264,7 +264,7 @@ func (s *session) cleanRetryInfo() {
for i, stmtID := range retryInfo.DroppedPreparedStmtIDs {
if planCacheEnabled {
if i > 0 && preparedAst != nil {
plannercore.SetPstmtIDSchemaVersion(cacheKey, stmtID, preparedAst.SchemaVersion)
plannercore.SetPstmtIDSchemaVersion(cacheKey, stmtID, preparedAst.SchemaVersion, s.sessionVars.IsolationReadEngines)
}
s.PreparedPlanCache().Delete(cacheKey)
}
Expand Down

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