diff --git a/privilege/privileges/cache.go b/privilege/privileges/cache.go
index 3ff9e6b0c28bb..d00dc99bb076c 100644
--- a/privilege/privileges/cache.go
+++ b/privilege/privileges/cache.go
@@ -156,7 +156,7 @@ func noSuchTable(err error) bool {
 
 // LoadUserTable loads the mysql.user table from database.
 func (p *MySQLPrivilege) LoadUserTable(ctx sessionctx.Context) error {
-	err := p.loadTable(ctx, "select Host,User,Password,Select_priv,Insert_priv,Update_priv,Delete_priv,Create_priv,Drop_priv,Process_priv,Grant_priv,References_priv,Alter_priv,Show_db_priv,Super_priv,Execute_priv,Index_priv,Create_user_priv,Trigger_priv from mysql.user;", p.decodeUserTableRow)
+	err := p.loadTable(ctx, "select HIGH_PRIORITY Host,User,Password,Select_priv,Insert_priv,Update_priv,Delete_priv,Create_priv,Drop_priv,Process_priv,Grant_priv,References_priv,Alter_priv,Show_db_priv,Super_priv,Execute_priv,Index_priv,Create_user_priv,Trigger_priv from mysql.user;", p.decodeUserTableRow)
 	if err != nil {
 		return errors.Trace(err)
 	}
@@ -253,17 +253,17 @@ func (p MySQLPrivilege) SortUserTable() {
 
 // LoadDBTable loads the mysql.db table from database.
 func (p *MySQLPrivilege) LoadDBTable(ctx sessionctx.Context) error {
-	return p.loadTable(ctx, "select Host,DB,User,Select_priv,Insert_priv,Update_priv,Delete_priv,Create_priv,Drop_priv,Grant_priv,Index_priv,Alter_priv,Execute_priv from mysql.db order by host, db, user;", p.decodeDBTableRow)
+	return p.loadTable(ctx, "select HIGH_PRIORITY Host,DB,User,Select_priv,Insert_priv,Update_priv,Delete_priv,Create_priv,Drop_priv,Grant_priv,Index_priv,Alter_priv,Execute_priv from mysql.db order by host, db, user;", p.decodeDBTableRow)
 }
 
 // LoadTablesPrivTable loads the mysql.tables_priv table from database.
 func (p *MySQLPrivilege) LoadTablesPrivTable(ctx sessionctx.Context) error {
-	return p.loadTable(ctx, "select Host,DB,User,Table_name,Grantor,Timestamp,Table_priv,Column_priv from mysql.tables_priv", p.decodeTablesPrivTableRow)
+	return p.loadTable(ctx, "select HIGH_PRIORITY Host,DB,User,Table_name,Grantor,Timestamp,Table_priv,Column_priv from mysql.tables_priv", p.decodeTablesPrivTableRow)
 }
 
 // LoadColumnsPrivTable loads the mysql.columns_priv table from database.
 func (p *MySQLPrivilege) LoadColumnsPrivTable(ctx sessionctx.Context) error {
-	return p.loadTable(ctx, "select Host,DB,User,Table_name,Column_name,Timestamp,Column_priv from mysql.columns_priv", p.decodeColumnsPrivTableRow)
+	return p.loadTable(ctx, "select HIGH_PRIORITY Host,DB,User,Table_name,Column_name,Timestamp,Column_priv from mysql.columns_priv", p.decodeColumnsPrivTableRow)
 }
 
 func (p *MySQLPrivilege) loadTable(sctx sessionctx.Context, sql string,
diff --git a/server/server.go b/server/server.go
index 942c39df4dc81..4512a60bc20be 100644
--- a/server/server.go
+++ b/server/server.go
@@ -36,11 +36,11 @@ import (
 	"math/rand"
 	"net"
 	"net/http"
+	// For pprof
+	_ "net/http/pprof"
 	"sync"
 	"sync/atomic"
 	"time"
-	// For pprof
-	_ "net/http/pprof"
 
 	"github.com/blacktear23/go-proxyprotocol"
 	"github.com/juju/errors"
diff --git a/session/bootstrap.go b/session/bootstrap.go
index 724600f4de74d..c4298907d66b3 100644
--- a/session/bootstrap.go
+++ b/session/bootstrap.go
@@ -286,7 +286,7 @@ func checkBootstrapped(s Session) (bool, error) {
 // getTiDBVar gets variable value from mysql.tidb table.
 // Those variables are used by TiDB server.
 func getTiDBVar(s Session, name string) (sVal string, isNull bool, e error) {
-	sql := fmt.Sprintf(`SELECT VARIABLE_VALUE FROM %s.%s WHERE VARIABLE_NAME="%s"`,
+	sql := fmt.Sprintf(`SELECT HIGH_PRIORITY VARIABLE_VALUE FROM %s.%s WHERE VARIABLE_NAME="%s"`,
 		mysql.SystemDB, mysql.TiDBTable, name)
 	ctx := context.Background()
 	rs, err := s.Execute(ctx, sql)
@@ -436,7 +436,7 @@ func upgradeToVer2(s Session) {
 		value := fmt.Sprintf(`("%s", "%s")`, v, variable.SysVars[v].Value)
 		values = append(values, value)
 	}
-	sql := fmt.Sprintf("INSERT IGNORE INTO %s.%s VALUES %s;", mysql.SystemDB, mysql.GlobalVariablesTable,
+	sql := fmt.Sprintf("INSERT HIGH_PRIORITY IGNORE INTO %s.%s VALUES %s;", mysql.SystemDB, mysql.GlobalVariablesTable,
 		strings.Join(values, ", "))
 	mustExecute(s, sql)
 }
@@ -444,7 +444,7 @@ func upgradeToVer2(s Session) {
 // upgradeToVer3 updates to version 3.
 func upgradeToVer3(s Session) {
 	// Version 3 fix tx_read_only variable value.
-	sql := fmt.Sprintf("UPDATE %s.%s set variable_value = '0' where variable_name = 'tx_read_only';",
+	sql := fmt.Sprintf("UPDATE HIGH_PRIORITY %s.%s set variable_value = '0' where variable_name = 'tx_read_only';",
 		mysql.SystemDB, mysql.GlobalVariablesTable)
 	mustExecute(s, sql)
 }
@@ -463,18 +463,18 @@ func upgradeToVer5(s Session) {
 func upgradeToVer6(s Session) {
 	doReentrantDDL(s, "ALTER TABLE mysql.user ADD COLUMN `Super_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N' AFTER `Show_db_priv`", infoschema.ErrColumnExists)
 	// For reasons of compatibility, set the non-exists privilege column value to 'Y', as TiDB doesn't check them in older versions.
-	mustExecute(s, "UPDATE mysql.user SET Super_priv='Y'")
+	mustExecute(s, "UPDATE HIGH_PRIORITY mysql.user SET Super_priv='Y'")
 }
 
 func upgradeToVer7(s Session) {
 	doReentrantDDL(s, "ALTER TABLE mysql.user ADD COLUMN `Process_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N' AFTER `Drop_priv`", infoschema.ErrColumnExists)
 	// For reasons of compatibility, set the non-exists privilege column value to 'Y', as TiDB doesn't check them in older versions.
-	mustExecute(s, "UPDATE mysql.user SET Process_priv='Y'")
+	mustExecute(s, "UPDATE HIGH_PRIORITY mysql.user SET Process_priv='Y'")
 }
 
 func upgradeToVer8(s Session) {
 	// This is a dummy upgrade, it checks whether upgradeToVer7 success, if not, do it again.
-	if _, err := s.Execute(context.Background(), "SELECT `Process_priv` from mysql.user limit 0"); err == nil {
+	if _, err := s.Execute(context.Background(), "SELECT HIGH_PRIORITY `Process_priv` from mysql.user limit 0"); err == nil {
 		return
 	}
 	upgradeToVer7(s)
@@ -483,7 +483,7 @@ func upgradeToVer8(s Session) {
 func upgradeToVer9(s Session) {
 	doReentrantDDL(s, "ALTER TABLE mysql.user ADD COLUMN `Trigger_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N' AFTER `Create_user_priv`", infoschema.ErrColumnExists)
 	// For reasons of compatibility, set the non-exists privilege column value to 'Y', as TiDB doesn't check them in older versions.
-	mustExecute(s, "UPDATE mysql.user SET Trigger_priv='Y'")
+	mustExecute(s, "UPDATE HIGH_PRIORITY mysql.user SET Trigger_priv='Y'")
 }
 
 func doReentrantDDL(s Session, sql string, ignorableErrs ...error) {
@@ -514,14 +514,14 @@ func upgradeToVer11(s Session) {
 		}
 		log.Fatal(err)
 	}
-	mustExecute(s, "UPDATE mysql.user SET References_priv='Y'")
+	mustExecute(s, "UPDATE HIGH_PRIORITY mysql.user SET References_priv='Y'")
 }
 
 func upgradeToVer12(s Session) {
 	ctx := context.Background()
 	_, err := s.Execute(ctx, "BEGIN")
 	terror.MustNil(err)
-	sql := "SELECT user, host, password FROM mysql.user WHERE password != ''"
+	sql := "SELECT HIGH_PRIORITY user, host, password FROM mysql.user WHERE password != ''"
 	rs, err := s.Execute(ctx, sql)
 	terror.MustNil(err)
 	r := rs[0]
@@ -538,7 +538,7 @@ func upgradeToVer12(s Session) {
 			var newPass string
 			newPass, err = oldPasswordUpgrade(pass)
 			terror.MustNil(err)
-			updateSQL := fmt.Sprintf(`UPDATE mysql.user set password = "%s" where user="%s" and host="%s"`, newPass, user, host)
+			updateSQL := fmt.Sprintf(`UPDATE HIGH_PRIORITY mysql.user set password = "%s" where user="%s" and host="%s"`, newPass, user, host)
 			sqls = append(sqls, updateSQL)
 		}
 		err = r.Next(ctx, chk)
@@ -549,7 +549,7 @@ func upgradeToVer12(s Session) {
 		mustExecute(s, sql)
 	}
 
-	sql = fmt.Sprintf(`INSERT INTO %s.%s VALUES ("%s", "%d", "TiDB bootstrap version.") ON DUPLICATE KEY UPDATE VARIABLE_VALUE="%d"`,
+	sql = fmt.Sprintf(`INSERT HIGH_PRIORITY INTO %s.%s VALUES ("%s", "%d", "TiDB bootstrap version.") ON DUPLICATE KEY UPDATE VARIABLE_VALUE="%d"`,
 		mysql.SystemDB, mysql.TiDBTable, tidbServerVersionVar, version12, version12)
 	mustExecute(s, sql)
 
@@ -576,7 +576,7 @@ func upgradeToVer13(s Session) {
 			log.Fatal(err)
 		}
 	}
-	mustExecute(s, "UPDATE mysql.user SET Create_tmp_table_priv='Y',Lock_tables_priv='Y',Create_view_priv='Y',Show_view_priv='Y',Create_routine_priv='Y',Alter_routine_priv='Y',Event_priv='Y'")
+	mustExecute(s, "UPDATE HIGH_PRIORITY mysql.user SET Create_tmp_table_priv='Y',Lock_tables_priv='Y',Create_view_priv='Y',Show_view_priv='Y',Create_routine_priv='Y',Alter_routine_priv='Y',Event_priv='Y'")
 }
 
 func upgradeToVer14(s Session) {
@@ -652,7 +652,7 @@ func upgradeToVer23(s Session) {
 // updateBootstrapVer updates bootstrap version variable in mysql.TiDB table.
 func updateBootstrapVer(s Session) {
 	// Update bootstrap version.
-	sql := fmt.Sprintf(`INSERT INTO %s.%s VALUES ("%s", "%d", "TiDB bootstrap version.") ON DUPLICATE KEY UPDATE VARIABLE_VALUE="%d"`,
+	sql := fmt.Sprintf(`INSERT HIGH_PRIORITY INTO %s.%s VALUES ("%s", "%d", "TiDB bootstrap version.") ON DUPLICATE KEY UPDATE VARIABLE_VALUE="%d"`,
 		mysql.SystemDB, mysql.TiDBTable, tidbServerVersionVar, currentBootstrapVersion, currentBootstrapVersion)
 	mustExecute(s, sql)
 }
@@ -707,7 +707,7 @@ func doDMLWorks(s Session) {
 	mustExecute(s, "BEGIN")
 
 	// Insert a default user with empty password.
-	mustExecute(s, `INSERT INTO mysql.user VALUES
+	mustExecute(s, `INSERT HIGH_PRIORITY INTO mysql.user VALUES
 		("%", "root", "", "Y", "Y", "Y", "Y", "Y", "Y", "Y", "Y", "Y", "Y", "Y", "Y", "Y", "Y", "Y", "Y", "Y", "Y", "Y", "Y", "Y", "Y", "Y")`)
 
 	// Init global system variables table.
@@ -719,16 +719,16 @@ func doDMLWorks(s Session) {
 			values = append(values, value)
 		}
 	}
-	sql := fmt.Sprintf("INSERT INTO %s.%s VALUES %s;", mysql.SystemDB, mysql.GlobalVariablesTable,
+	sql := fmt.Sprintf("INSERT HIGH_PRIORITY INTO %s.%s VALUES %s;", mysql.SystemDB, mysql.GlobalVariablesTable,
 		strings.Join(values, ", "))
 	mustExecute(s, sql)
 
-	sql = fmt.Sprintf(`INSERT INTO %s.%s VALUES("%s", "%s", "Bootstrap flag. Do not delete.")
+	sql = fmt.Sprintf(`INSERT HIGH_PRIORITY INTO %s.%s VALUES("%s", "%s", "Bootstrap flag. Do not delete.")
 		ON DUPLICATE KEY UPDATE VARIABLE_VALUE="%s"`,
 		mysql.SystemDB, mysql.TiDBTable, bootstrappedVar, bootstrappedVarTrue, bootstrappedVarTrue)
 	mustExecute(s, sql)
 
-	sql = fmt.Sprintf(`INSERT INTO %s.%s VALUES("%s", "%d", "Bootstrap version. Do not delete.")`,
+	sql = fmt.Sprintf(`INSERT HIGH_PRIORITY INTO %s.%s VALUES("%s", "%d", "Bootstrap version. Do not delete.")`,
 		mysql.SystemDB, mysql.TiDBTable, tidbServerVersionVar, currentBootstrapVersion)
 	mustExecute(s, sql)
 
diff --git a/statistics/boostrap.go b/statistics/bootstrap.go
similarity index 94%
rename from statistics/boostrap.go
rename to statistics/bootstrap.go
index 938ccf0f31296..726c44bf2fe4d 100644
--- a/statistics/boostrap.go
+++ b/statistics/bootstrap.go
@@ -58,7 +58,7 @@ func (h *Handle) initStatsMeta4Chunk(is infoschema.InfoSchema, tables statsCache
 func (h *Handle) initStatsMeta(is infoschema.InfoSchema) (statsCache, error) {
 	h.mu.Lock()
 	defer h.mu.Unlock()
-	sql := "select version, table_id, modify_count, count from mysql.stats_meta"
+	sql := "select HIGH_PRIORITY version, table_id, modify_count, count from mysql.stats_meta"
 	rc, err := h.mu.ctx.(sqlexec.SQLExecutor).Execute(context.TODO(), sql)
 	if len(rc) > 0 {
 		defer terror.Call(rc[0].Close)
@@ -128,7 +128,7 @@ func (h *Handle) initStatsHistograms4Chunk(is infoschema.InfoSchema, tables stat
 func (h *Handle) initStatsHistograms(is infoschema.InfoSchema, tables statsCache) error {
 	h.mu.Lock()
 	defer h.mu.Unlock()
-	sql := "select table_id, is_index, hist_id, distinct_count, version, null_count, cm_sketch, tot_col_size, stats_ver from mysql.stats_histograms"
+	sql := "select HIGH_PRIORITY table_id, is_index, hist_id, distinct_count, version, null_count, cm_sketch, tot_col_size, stats_ver from mysql.stats_histograms"
 	rc, err := h.mu.ctx.(sqlexec.SQLExecutor).Execute(context.TODO(), sql)
 	if len(rc) > 0 {
 		defer terror.Call(rc[0].Close)
@@ -200,7 +200,7 @@ func initStatsBuckets4Chunk(ctx sessionctx.Context, tables statsCache, iter *chu
 func (h *Handle) initStatsBuckets(tables statsCache) error {
 	h.mu.Lock()
 	defer h.mu.Unlock()
-	sql := "select table_id, is_index, hist_id, count, repeats, lower_bound, upper_bound from mysql.stats_buckets order by table_id, is_index, hist_id, bucket_id"
+	sql := "select HIGH_PRIORITY table_id, is_index, hist_id, count, repeats, lower_bound, upper_bound from mysql.stats_buckets order by table_id, is_index, hist_id, bucket_id"
 	rc, err := h.mu.ctx.(sqlexec.SQLExecutor).Execute(context.TODO(), sql)
 	if len(rc) > 0 {
 		defer terror.Call(rc[0].Close)
diff --git a/store/tikv/gcworker/gc_worker.go b/store/tikv/gcworker/gc_worker.go
index 9f4885321540f..cfe0a9fbdb9e7 100644
--- a/store/tikv/gcworker/gc_worker.go
+++ b/store/tikv/gcworker/gc_worker.go
@@ -872,7 +872,7 @@ func (w *GCWorker) loadValueFromSysTable(key string) (string, error) {
 }
 
 func (w *GCWorker) saveValueToSysTable(key, value string) error {
-	stmt := fmt.Sprintf(`INSERT INTO mysql.tidb VALUES ('%[1]s', '%[2]s', '%[3]s')
+	stmt := fmt.Sprintf(`INSERT HIGH_PRIORITY INTO mysql.tidb VALUES ('%[1]s', '%[2]s', '%[3]s')
 			       ON DUPLICATE KEY
 			       UPDATE variable_value = '%[2]s', comment = '%[3]s'`,
 		key, value, gcVariableComments[key])