251 lines
6.8 KiB
Go
251 lines
6.8 KiB
Go
// Copyright 2016 PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package executor
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import (
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"fmt"
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"strings"
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"time"
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log "github.com/Sirupsen/logrus"
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"github.com/juju/errors"
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"github.com/pingcap/tidb/ast"
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"github.com/pingcap/tidb/context"
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"github.com/pingcap/tidb/domain"
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"github.com/pingcap/tidb/expression"
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"github.com/pingcap/tidb/kv"
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"github.com/pingcap/tidb/sessionctx/variable"
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"github.com/pingcap/tidb/sessionctx/varsutil"
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"github.com/pingcap/tidb/terror"
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"github.com/pingcap/tidb/types"
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"github.com/pingcap/tidb/util/charset"
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"github.com/pingcap/tidb/util/sqlexec"
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goctx "golang.org/x/net/context"
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)
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// SetExecutor executes set statement.
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type SetExecutor struct {
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baseExecutor
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vars []*expression.VarAssignment
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done bool
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}
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// Next implements the Executor Next interface.
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func (e *SetExecutor) Next(goCtx goctx.Context) (Row, error) {
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if e.done {
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return nil, nil
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}
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err := e.executeSet()
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if err != nil {
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return nil, errors.Trace(err)
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}
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e.done = true
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return nil, nil
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}
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func (e *SetExecutor) executeSet() error {
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sessionVars := e.ctx.GetSessionVars()
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for _, v := range e.vars {
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// Variable is case insensitive, we use lower case.
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if v.Name == ast.SetNames {
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// This is set charset stmt.
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dt, err := v.Expr.(*expression.Constant).Eval(nil)
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if err != nil {
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return errors.Trace(err)
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}
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cs := dt.GetString()
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var co string
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if v.ExtendValue != nil {
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co = v.ExtendValue.Value.GetString()
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}
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err = e.setCharset(cs, co)
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if err != nil {
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return errors.Trace(err)
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}
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continue
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}
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name := strings.ToLower(v.Name)
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if !v.IsSystem {
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// Set user variable.
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value, err := v.Expr.Eval(nil)
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if err != nil {
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return errors.Trace(err)
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}
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if value.IsNull() {
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delete(sessionVars.Users, name)
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} else {
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svalue, err1 := value.ToString()
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if err1 != nil {
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return errors.Trace(err1)
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}
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sessionVars.Users[name] = fmt.Sprintf("%v", svalue)
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}
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continue
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}
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// Set system variable
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sysVar := variable.GetSysVar(name)
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if sysVar == nil {
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return variable.UnknownSystemVar.GenByArgs(name)
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}
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if sysVar.Scope == variable.ScopeNone {
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return errors.Errorf("Variable '%s' is a read only variable", name)
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}
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if v.IsGlobal {
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// Set global scope system variable.
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if sysVar.Scope&variable.ScopeGlobal == 0 {
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return errors.Errorf("Variable '%s' is a SESSION variable and can't be used with SET GLOBAL", name)
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}
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value, err := e.getVarValue(v, sysVar)
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if err != nil {
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return errors.Trace(err)
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}
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if value.IsNull() {
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value.SetString("")
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}
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svalue, err := value.ToString()
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if err != nil {
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return errors.Trace(err)
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}
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err = sessionVars.GlobalVarsAccessor.SetGlobalSysVar(name, svalue)
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if err != nil {
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return errors.Trace(err)
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}
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} else {
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// Set session scope system variable.
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if sysVar.Scope&variable.ScopeSession == 0 {
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return errors.Errorf("Variable '%s' is a GLOBAL variable and should be set with SET GLOBAL", name)
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}
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value, err := e.getVarValue(v, nil)
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if err != nil {
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return errors.Trace(err)
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}
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oldSnapshotTS := sessionVars.SnapshotTS
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err = varsutil.SetSessionSystemVar(sessionVars, name, value)
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if err != nil {
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return errors.Trace(err)
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}
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newSnapshotIsSet := sessionVars.SnapshotTS > 0 && sessionVars.SnapshotTS != oldSnapshotTS
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if newSnapshotIsSet {
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err = validateSnapshot(e.ctx, sessionVars.SnapshotTS)
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if err != nil {
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sessionVars.SnapshotTS = oldSnapshotTS
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return errors.Trace(err)
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}
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}
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err = e.loadSnapshotInfoSchemaIfNeeded(name)
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if err != nil {
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sessionVars.SnapshotTS = oldSnapshotTS
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return errors.Trace(err)
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}
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var valStr string
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if value.IsNull() {
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valStr = "NULL"
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} else {
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var err error
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valStr, err = value.ToString()
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terror.Log(errors.Trace(err))
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}
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log.Infof("[%d] set system variable %s = %s", sessionVars.ConnectionID, name, valStr)
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}
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if name == variable.TxnIsolation {
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if sessionVars.Systems[variable.TxnIsolation] == ast.ReadCommitted {
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e.ctx.Txn().SetOption(kv.IsolationLevel, kv.RC)
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}
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}
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}
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return nil
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}
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// validateSnapshot checks that the newly set snapshot time is after GC safe point time.
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func validateSnapshot(ctx context.Context, snapshotTS uint64) error {
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sql := "SELECT variable_value FROM mysql.tidb WHERE variable_name = 'tikv_gc_safe_point'"
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rows, _, err := ctx.(sqlexec.RestrictedSQLExecutor).ExecRestrictedSQL(ctx, sql)
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if err != nil {
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return errors.Trace(err)
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}
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if len(rows) != 1 {
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return errors.New("can not get 'tikv_gc_safe_point'")
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}
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safePointString := rows[0].GetString(0)
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const gcTimeFormat = "20060102-15:04:05 -0700 MST"
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safePointTime, err := time.Parse(gcTimeFormat, safePointString)
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if err != nil {
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return errors.Trace(err)
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}
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safePointTS := varsutil.GoTimeToTS(safePointTime)
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if safePointTS > snapshotTS {
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return variable.ErrSnapshotTooOld.GenByArgs(safePointString)
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}
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return nil
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}
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func (e *SetExecutor) setCharset(cs, co string) error {
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var err error
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if len(co) == 0 {
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co, err = charset.GetDefaultCollation(cs)
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if err != nil {
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return errors.Trace(err)
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}
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}
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sessionVars := e.ctx.GetSessionVars()
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for _, v := range variable.SetNamesVariables {
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sessionVars.Systems[v] = cs
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}
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sessionVars.Systems[variable.CollationConnection] = co
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return nil
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}
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func (e *SetExecutor) getVarValue(v *expression.VarAssignment, sysVar *variable.SysVar) (value types.Datum, err error) {
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if v.IsDefault {
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// To set a SESSION variable to the GLOBAL value or a GLOBAL value
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// to the compiled-in MySQL default value, use the DEFAULT keyword.
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// See http://dev.mysql.com/doc/refman/5.7/en/set-statement.html
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if sysVar != nil {
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value = types.NewStringDatum(sysVar.Value)
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} else {
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s, err1 := varsutil.GetGlobalSystemVar(e.ctx.GetSessionVars(), v.Name)
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if err1 != nil {
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return value, errors.Trace(err1)
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}
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value = types.NewStringDatum(s)
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}
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return
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}
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value, err = v.Expr.Eval(nil)
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return value, errors.Trace(err)
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}
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func (e *SetExecutor) loadSnapshotInfoSchemaIfNeeded(name string) error {
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if name != variable.TiDBSnapshot {
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return nil
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}
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vars := e.ctx.GetSessionVars()
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if vars.SnapshotTS == 0 {
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vars.SnapshotInfoschema = nil
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return nil
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}
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log.Infof("[%d] loadSnapshotInfoSchema, SnapshotTS:%d", vars.ConnectionID, vars.SnapshotTS)
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dom := domain.GetDomain(e.ctx)
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snapInfo, err := dom.GetSnapshotInfoSchema(vars.SnapshotTS)
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if err != nil {
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return errors.Trace(err)
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}
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vars.SnapshotInfoschema = snapInfo
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return nil
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}
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