*: merge master and fix conflict.

2015-11-12 10:21:50 +08:00
parent 1fccd95733 3b59e0c404
commit 542bfebd36
25 changed files with 834 additions and 75 deletions
--- a/.gitignore
+++ b/.gitignore
@ -4,3 +4,5 @@
 /interpreter/test
 /tidb-server/tidb-server
 coverage.out
+.idea/
+*.iml
--- a/ast/misc.go
+++ b/ast/misc.go
@ -162,6 +162,7 @@ const (
 	ShowWarnings
 	ShowCharset
 	ShowVariables
+	ShowStatus
 	ShowCollation
 	ShowCreateTable
 	ShowGrants
--- a/ddl/ddl.go
+++ b/ddl/ddl.go
@ -33,7 +33,6 @@ import (
 	"github.com/pingcap/tidb/model"
 	"github.com/pingcap/tidb/mysql"
 	"github.com/pingcap/tidb/parser/coldef"
-	"github.com/pingcap/tidb/privilege"
 	"github.com/pingcap/tidb/table"
 	"github.com/pingcap/tidb/terror"
 	"github.com/pingcap/tidb/util/charset"
@ -561,15 +560,6 @@ func (d *ddl) DropTable(ctx context.Context, ti table.Ident) (err error) {
 	if err != nil {
 		return errors.Trace(ErrNotExists)
 	}
-	// Check Privilege
-	privChecker := privilege.GetPrivilegeChecker(ctx)
-	hasPriv, err := privChecker.Check(ctx, schema, tb.Meta(), mysql.DropPriv)
-	if err != nil {
-		return errors.Trace(err)
-	}
-	if !hasPriv {
-		return errors.Errorf("You do not have the privilege to drop table %s.%s.", ti.Schema, ti.Name)
-	}

 	job := &model.Job{
 		SchemaID: schema.ID,
--- a/expression/variable.go
+++ b/expression/variable.go
@ -62,7 +62,7 @@ func (v *Variable) String() string {
 func (v *Variable) Eval(ctx context.Context, args map[interface{}]interface{}) (interface{}, error) {
 	name := strings.ToLower(v.Name)
 	sessionVars := variable.GetSessionVars(ctx)
-	globalVars := variable.GetGlobalSysVarAccessor(ctx)
+	globalVars := variable.GetGlobalVarAccessor(ctx)
 	if !v.IsSystem {
 		// user vars
 		if value, ok := sessionVars.Users[name]; ok {
--- a/expression/variable_test.go
+++ b/expression/variable_test.go
@ -30,7 +30,7 @@ func (s *testVariableSuite) SetUpSuite(c *C) {
 	nc := mock.NewContext()
 	s.ctx = nc
 	variable.BindSessionVars(s.ctx)
-	variable.BindGlobalSysVarAccessor(s.ctx, nc)
+	variable.BindGlobalVarAccessor(s.ctx, nc)
 }

 func (s *testVariableSuite) TestVariable(c *C) {
--- a/optimizer/convert_stmt.go
+++ b/optimizer/convert_stmt.go
@ -868,6 +868,8 @@ func convertShow(converter *expressionConverter, v *ast.ShowStmt) (*stmts.ShowSt
 		oldShow.Target = stmt.ShowEngines
 	case ast.ShowVariables:
 		oldShow.Target = stmt.ShowVariables
+	case ast.ShowStatus:
+		oldShow.Target = stmt.ShowStatus
 	case ast.ShowWarnings:
 		oldShow.Target = stmt.ShowWarnings
 	case ast.ShowNone:
--- a/parser/parser.y
+++ b/parser/parser.y
@ -228,6 +228,7 @@ import (
 	signed		"SIGNED"
 	some 		"SOME"
 	start		"START"
+	status		"STATUS"
 	stringType	"string"
 	subDate		"SUBDATE"
 	substring	"SUBSTRING"
@ -482,10 +483,10 @@ import (
 	SelectStmtOpts		"Select statement options"
 	SelectStmtGroup		"SELECT statement optional GROUP BY clause"
 	SetStmt			"Set variable statement"
-	ShowStmt		"Show engines/databases/tables/columns/warnings statement"
+	ShowStmt		"Show engines/databases/tables/columns/warnings/status statement"
 	ShowDatabaseNameOpt	"Show tables/columns statement database name option"
 	ShowTableAliasOpt       "Show table alias option"
-	ShowLikeOrWhereOpt	"Show like or where condition option"
+	ShowLikeOrWhereOpt	"Show like or where clause option"
 	SignedLiteral		"Literal or NumLiteral with sign"
 	Statement		"statement"
 	StatementList		"statement list"
@ -1647,7 +1648,7 @@ UnReservedKeyword:
 	"AUTO_INCREMENT" | "AFTER" | "AVG" | "BEGIN" | "BIT" | "BOOL" | "BOOLEAN" | "CHARSET" | "COLUMNS" | "COMMIT" 
 |	"DATE" | "DATETIME" | "DEALLOCATE" | "DO" | "END" | "ENGINE" | "ENGINES" | "EXECUTE" | "FIRST" | "FULL" 
 |	"LOCAL" | "NAMES" | "OFFSET" | "PASSWORD" %prec lowerThanEq | "PREPARE" | "QUICK" | "ROLLBACK" | "SESSION" | "SIGNED" 
-|	"START" | "GLOBAL" | "TABLES"| "TEXT" | "TIME" | "TIMESTAMP" | "TRANSACTION" | "TRUNCATE" | "UNKNOWN" 
+|	"START" | "STATUS" | "GLOBAL" | "TABLES"| "TEXT" | "TIME" | "TIMESTAMP" | "TRANSACTION" | "TRUNCATE" | "UNKNOWN"
 |	"VALUE" | "WARNINGS" | "YEAR" |	"MODE" | "WEEK" | "ANY" | "SOME" | "USER" | "IDENTIFIED" | "COLLATION"
 |	"COMMENT" | "AVG_ROW_LENGTH" | "CONNECTION" | "CHECKSUM" | "COMPRESSION" | "KEY_BLOCK_SIZE" | "MAX_ROWS" | "MIN_ROWS"
 |	"NATIONAL" | "ROW" | "QUARTER" | "ESCAPE" | "GRANTS"
@ -3316,6 +3317,19 @@ ShowStmt:
 		}
 		$$ = stmt
 	}
+|	"SHOW" GlobalScope "STATUS" ShowLikeOrWhereOpt
+	{
+		stmt := &ast.ShowStmt{
+			Tp: ast.ShowStatus,
+			GlobalScope: $2.(bool),
+		}
+		if x, ok := $4.(*ast.PatternLikeExpr); ok {
+			stmt.Pattern = x
+		} else if $4 != nil {
+			stmt.Where = $4.(ast.ExprNode)
+		}
+		$$ = stmt
+	}
 |	"SHOW" "COLLATION" ShowLikeOrWhereOpt
 	{
 		stmt := &ast.ShowStmt{
--- a/parser/parser_test.go
+++ b/parser/parser_test.go
@ -240,6 +240,11 @@ func (s *testParserSuite) TestDMLStmt(c *C) {
 		{"SHOW VARIABLES", true},
 		{"SHOW GLOBAL VARIABLES", true},
 		{"SHOW GLOBAL VARIABLES WHERE Variable_name = 'autocommit'", true},
+		{"SHOW STATUS", true},
+		{"SHOW GLOBAL STATUS", true},
+		{"SHOW SESSION STATUS", true},
+		{"SHOW STATUS LIKE 'Up%'", true},
+		{"SHOW STATUS WHERE Variable_name LIKE 'Up%'", true},
 		{`SHOW FULL TABLES FROM icar_qa LIKE play_evolutions`, true},
 		{`SHOW FULL TABLES WHERE Table_Type != 'VIEW'`, true},
 		{`SHOW GRANTS`, true},
--- a/parser/scanner.l
+++ b/parser/scanner.l
@ -430,6 +430,7 @@ share		{s}{h}{a}{r}{e}
 show		{s}{h}{o}{w}
 some		{s}{o}{m}{e}
 start		{s}{t}{a}{r}{t}
+status          {s}{t}{a}{t}{u}{s}
 subdate		{s}{u}{b}{d}{a}{t}{e}
 substring	{s}{u}{b}{s}{t}{r}{i}{n}{g}
 substring_index	{s}{u}{b}{s}{t}{r}{i}{n}{g}_{i}{n}{d}{e}{x}
@ -841,6 +842,8 @@ year_month		{y}{e}{a}{r}_{m}{o}{n}{t}{h}
 			return some
 {start}			lval.item = string(l.val)
 			return start
+{status}		lval.item = string(l.val)
+			return status
 {global}		lval.item = string(l.val)
 			return global
 {rand}			lval.item = string(l.val)
--- a/plan/plans/from.go
+++ b/plan/plans/from.go
@ -148,6 +148,7 @@ func (r *TableDefaultPlan) filterBinOp(ctx context.Context, x *expression.Binary
 	return &indexPlan{
 		src:     t,
 		col:     c,
+		unique:  ix.Unique,
 		idxName: ix.Name.O,
 		idx:     ix.X,
 		spans:   toSpans(x.Op, rval, seekVal),
@ -179,6 +180,7 @@ func (r *TableDefaultPlan) filterIdent(ctx context.Context, x *expression.Ident,
 		return &indexPlan{
 			src:     t,
 			col:     v,
+			unique:  ix.Unique,
 			idxName: ix.Name.L,
 			idx:     ix.X,
 			spans:   spans,
@ -215,6 +217,7 @@ func (r *TableDefaultPlan) filterIsNull(ctx context.Context, x *expression.IsNul
 	return &indexPlan{
 		src:     t,
 		col:     col,
+		unique:  ix.Unique,
 		idxName: ix.Name.L,
 		idx:     ix.X,
 		spans:   spans,
--- a/plan/plans/index.go
+++ b/plan/plans/index.go
@ -25,6 +25,7 @@ import (
 	"github.com/pingcap/tidb/parser/opcode"
 	"github.com/pingcap/tidb/plan"
 	"github.com/pingcap/tidb/table"
+	"github.com/pingcap/tidb/terror"
 	"github.com/pingcap/tidb/util/format"
 	"github.com/pingcap/tidb/util/types"
 )
@ -124,6 +125,7 @@ func (span *indexSpan) cutOffHigh(val interface{}, exclude bool) *indexSpan {
 type indexPlan struct {
 	src        table.Table
 	col        *column.Col
+	unique     bool
 	idxName    string
 	idx        kv.Index
 	spans      []*indexSpan // multiple spans are ordered by their values and without overlapping.
@ -243,6 +245,7 @@ func (r *indexPlan) Filter(ctx context.Context, expr expression.Expression) (pla
 	return &indexPlan{
 		src:     r.src,
 		col:     r.col,
+		unique:  r.unique,
 		idxName: r.idxName,
 		idx:     r.idx,
 		spans:   spans,
@ -325,19 +328,31 @@ func toSpans(op opcode.Op, val, seekVal interface{}) []*indexSpan {
 }

 // Next implements plan.Plan Next interface.
-func (r *indexPlan) Next(ctx context.Context) (row *plan.Row, err error) {
+func (r *indexPlan) Next(ctx context.Context) (*plan.Row, error) {
 	for {
 		if r.cursor == len(r.spans) {
-			return
+			return nil, nil
 		}
 		span := r.spans[r.cursor]
+		if r.isPointLookup(span) {
+			// Do point lookup on index will prevent prefetch cost.
+			row, err := r.pointLookup(ctx, span.lowVal)
+			if err != nil {
+				return nil, errors.Trace(err)
+			}
+			r.cursor++
+			if row != nil {
+				return row, nil
+			}
+			continue
+		}
 		if r.iter == nil {
 			seekVal := span.seekVal
 			if span.lowVal == minNotNullVal {
 				seekVal = []byte{}
 			}
 			var txn kv.Transaction
-			txn, err = ctx.GetTxn(false)
+			txn, err := ctx.GetTxn(false)
 			if err != nil {
 				return nil, errors.Trace(err)
 			}
@ -346,9 +361,7 @@ func (r *indexPlan) Next(ctx context.Context) (row *plan.Row, err error) {
 				return nil, types.EOFAsNil(err)
 			}
 		}
-		var idxKey []interface{}
-		var h int64
-		idxKey, h, err = r.iter.Next()
+		idxKey, h, err := r.iter.Next()
 		if err != nil {
 			return nil, types.EOFAsNil(err)
 		}
@ -370,20 +383,58 @@ func (r *indexPlan) Next(ctx context.Context) (row *plan.Row, err error) {
 			r.skipLowCmp = false
 			continue
 		}
-		row = &plan.Row{}
-		row.Data, err = r.src.Row(ctx, h)
+		var row *plan.Row
+		row, err = r.lookupRow(ctx, h)
 		if err != nil {
 			return nil, errors.Trace(err)
 		}
-		rowKey := &plan.RowKeyEntry{
-			Tbl: r.src,
-			Key: string(r.src.RecordKey(h, nil)),
-		}
-		row.RowKeys = append(row.RowKeys, rowKey)
-		return
+		return row, nil
 	}
 }

+func (r *indexPlan) isPointLookup(span *indexSpan) bool {
+	return r.unique && span.lowVal != nil && span.lowVal == span.highVal && !span.lowExclude && !span.highExclude
+}
+
+func (r *indexPlan) lookupRow(ctx context.Context, h int64) (*plan.Row, error) {
+	row := &plan.Row{}
+	var err error
+	row.Data, err = r.src.Row(ctx, h)
+	if err != nil {
+		return nil, errors.Trace(err)
+	}
+	rowKey := &plan.RowKeyEntry{
+		Tbl: r.src,
+		Key: string(r.src.RecordKey(h, nil)),
+	}
+	row.RowKeys = append(row.RowKeys, rowKey)
+	return row, nil
+}
+
+// pointLookup do not seek index but call Exists method to get a handle, which is cheaper.
+func (r *indexPlan) pointLookup(ctx context.Context, val interface{}) (*plan.Row, error) {
+	txn, err := ctx.GetTxn(false)
+	if err != nil {
+		return nil, errors.Trace(err)
+	}
+	var exist bool
+	var h int64
+	// We expect a kv.ErrKeyExists Error because we pass -1 as the handle which is not equal to the existed handle.
+	exist, h, err = r.idx.Exist(txn, []interface{}{val}, -1)
+	if !exist {
+		return nil, errors.Trace(err)
+	}
+	if terror.ErrorNotEqual(kv.ErrKeyExists, err) {
+		return nil, errors.Trace(err)
+	}
+	var row *plan.Row
+	row, err = r.lookupRow(ctx, h)
+	if err != nil {
+		return nil, errors.Trace(err)
+	}
+	return row, nil
+}
+
 // Close implements plan.Plan Close interface.
 func (r *indexPlan) Close() error {
 	if r.iter != nil {
--- a/plan/plans/show.go
+++ b/plan/plans/show.go
@ -32,6 +32,7 @@ import (
 	"github.com/pingcap/tidb/sessionctx/variable"
 	"github.com/pingcap/tidb/stmt"
 	"github.com/pingcap/tidb/table"
+	"github.com/pingcap/tidb/terror"
 	"github.com/pingcap/tidb/util/charset"
 	"github.com/pingcap/tidb/util/format"
 )
@ -103,6 +104,8 @@ func (s *ShowPlan) GetFields() []*field.ResultField {
 		types = []byte{mysql.TypeVarchar, mysql.TypeVarchar, mysql.TypeVarchar, mysql.TypeLonglong}
 	case stmt.ShowVariables:
 		names = []string{"Variable_name", "Value"}
+	case stmt.ShowStatus:
+		names = []string{"Variable_name", "Value"}
 	case stmt.ShowCollation:
 		names = []string{"Collation", "Charset", "Id", "Default", "Compiled", "Sortlen"}
 		types = []byte{mysql.TypeVarchar, mysql.TypeVarchar, mysql.TypeLonglong,
@ -164,6 +167,8 @@ func (s *ShowPlan) fetchAll(ctx context.Context) error {
 		return s.fetchShowCharset(ctx)
 	case stmt.ShowVariables:
 		return s.fetchShowVariables(ctx)
+	case stmt.ShowStatus:
+		return s.fetchShowStatus(ctx)
 	case stmt.ShowCollation:
 		return s.fetchShowCollation(ctx)
 	case stmt.ShowCreateTable:
@ -353,7 +358,7 @@ func (s *ShowPlan) fetchShowTables(ctx context.Context) error {

 func (s *ShowPlan) fetchShowVariables(ctx context.Context) error {
 	sessionVars := variable.GetSessionVars(ctx)
-	globalVars := variable.GetGlobalSysVarAccessor(ctx)
+	globalVars := variable.GetGlobalVarAccessor(ctx)
 	m := map[interface{}]interface{}{}

 	for _, v := range variable.SysVars {
@ -402,6 +407,86 @@ func (s *ShowPlan) fetchShowVariables(ctx context.Context) error {
 	return nil
 }

+func getSessionStatusVar(ctx context.Context, sessionVars *variable.SessionVars,
+	globalVars variable.GlobalVarAccessor, name string) (string, error) {
+	sv, ok := sessionVars.StatusVars[name]
+	if ok {
+		return sv, nil
+	}
+
+	value, err := globalVars.GetGlobalStatusVar(ctx, name)
+	if err != nil && terror.UnknownStatusVar.Equal(err) {
+		return "", errors.Trace(err)
+	}
+
+	return value, nil
+}
+
+func getGlobalStatusVar(ctx context.Context, sessionVars *variable.SessionVars,
+	globalVars variable.GlobalVarAccessor, name string) (string, error) {
+
+	value, err := globalVars.GetGlobalStatusVar(ctx, name)
+	if err == nil {
+		return value, nil
+	}
+
+	if terror.UnknownStatusVar.Equal(err) {
+		return "", errors.Trace(err)
+	}
+
+	sv, _ := sessionVars.StatusVars[name]
+
+	return sv, nil
+}
+
+func (s *ShowPlan) fetchShowStatus(ctx context.Context) error {
+	sessionVars := variable.GetSessionVars(ctx)
+	globalVars := variable.GetGlobalVarAccessor(ctx)
+	m := map[interface{}]interface{}{}
+
+	for _, v := range variable.StatusVars {
+		if s.Pattern != nil {
+			s.Pattern.Expr = expression.Value{Val: v.Name}
+		} else if s.Where != nil {
+			m[expression.ExprEvalIdentFunc] = func(name string) (interface{}, error) {
+				if strings.EqualFold(name, "Variable_name") {
+					return v.Name, nil
+				}
+
+				return nil, errors.Errorf("unknown field %s", name)
+			}
+		}
+
+		match, err := s.evalCondition(ctx, m)
+		if err != nil {
+			return errors.Trace(err)
+		}
+		if !match {
+			continue
+		}
+
+		var value string
+		if !s.GlobalScope {
+			value, err = getSessionStatusVar(ctx, sessionVars, globalVars, v.Name)
+			if err != nil {
+				return errors.Trace(err)
+			}
+		} else if v.Scope != variable.ScopeSession {
+			value, err = getGlobalStatusVar(ctx, sessionVars, globalVars, v.Name)
+			if err != nil {
+				return errors.Trace(err)
+			}
+		} else {
+			continue
+		}
+
+		row := &plan.Row{Data: []interface{}{v.Name, value}}
+		s.rows = append(s.rows, row)
+	}
+
+	return nil
+}
+
 func (s *ShowPlan) fetchShowCharset(ctx context.Context) error {
 	// See: http://dev.mysql.com/doc/refman/5.7/en/show-character-set.html
 	descs := charset.GetAllCharsets()
--- a/plan/plans/show_test.go
+++ b/plan/plans/show_test.go
@ -56,7 +56,7 @@ func (p *testShowSuit) SetUpSuite(c *C) {
 	nc := mock.NewContext()
 	p.ctx = nc
 	variable.BindSessionVars(p.ctx)
-	variable.BindGlobalSysVarAccessor(p.ctx, nc)
+	variable.BindGlobalVarAccessor(p.ctx, nc)

 	p.dbName = "testshowplan"
 	p.store = newStore(c, p.dbName)
@ -106,7 +106,7 @@ func (p *testShowSuit) TestSimple(c *C) {
 	c.Assert(fls, HasLen, 2)
 }

-func (p *testShowSuit) TestShowVariables(c *C) {
+func (p *testShowSuit) TestShowSysVariables(c *C) {
 	pln := &plans.ShowPlan{
 		Target:      stmt.ShowVariables,
 		GlobalScope: true,
@ -182,6 +182,94 @@ func (p *testShowSuit) TestShowVariables(c *C) {
 	c.Assert(v, Equals, "on")
 }

+func (p *testShowSuit) TestShowStatusVariables(c *C) {
+	pln := &plans.ShowPlan{
+		Target:      stmt.ShowStatus,
+		GlobalScope: true,
+		Pattern: &expression.PatternLike{
+			Pattern: &expression.Value{
+				Val: "tc_log_page_size",
+			},
+		},
+	}
+	fls := pln.GetFields()
+	c.Assert(fls, HasLen, 2)
+	c.Assert(fls[0].Name, Equals, "Variable_name")
+	c.Assert(fls[1].Name, Equals, "Value")
+	c.Assert(fls[0].Col.Tp, Equals, mysql.TypeVarchar)
+	c.Assert(fls[1].Col.Tp, Equals, mysql.TypeVarchar)
+
+	sessionVars := variable.GetSessionVars(p.ctx)
+	ret := map[string]string{}
+	rset := rsets.Recordset{
+		Ctx:  p.ctx,
+		Plan: pln,
+	}
+	rset.Do(func(data []interface{}) (bool, error) {
+		ret[data[0].(string)] = data[1].(string)
+		return true, nil
+	})
+	c.Assert(ret, HasLen, 1)
+	v, ok := ret["tc_log_page_size"]
+	c.Assert(ok, IsTrue)
+	c.Assert(v, Equals, "0")
+	pln.Close()
+
+	sessionVars.StatusVars["tc_log_page_size"] = "1024"
+	pln.GlobalScope = false
+	rset.Do(func(data []interface{}) (bool, error) {
+		ret[data[0].(string)] = data[1].(string)
+		return true, nil
+	})
+	c.Assert(ret, HasLen, 1)
+	v, ok = ret["tc_log_page_size"]
+	c.Assert(ok, IsTrue)
+	c.Assert(v, Equals, "1024")
+	pln.Close()
+
+	pln.Pattern = &expression.PatternLike{
+		Pattern: &expression.Value{
+			Val: "compression",
+		},
+	}
+	sessionVars.StatusVars["compression"] = "on"
+	pln.GlobalScope = true
+	ret = map[string]string{}
+	rset.Do(func(data []interface{}) (bool, error) {
+		ret[data[0].(string)] = data[1].(string)
+		return true, nil
+	})
+	c.Assert(ret, HasLen, 0)
+
+	pln.GlobalScope = false
+	rset.Do(func(data []interface{}) (bool, error) {
+		ret[data[0].(string)] = data[1].(string)
+		return true, nil
+	})
+	c.Assert(ret, HasLen, 1)
+	v, ok = ret["compression"]
+	c.Assert(ok, IsTrue)
+	c.Assert(v, Equals, "on")
+	pln.Close()
+
+	pln.Pattern = nil
+	pln.Where = &expression.BinaryOperation{
+		L:  &expression.Ident{CIStr: model.NewCIStr("Variable_name")},
+		R:  expression.Value{Val: "aborted_clients"},
+		Op: opcode.EQ,
+	}
+	ret = map[string]string{}
+	sessionVars.StatusVars["aborted_clients"] = "0"
+	rset.Do(func(data []interface{}) (bool, error) {
+		ret[data[0].(string)] = data[1].(string)
+		return true, nil
+	})
+	c.Assert(ret, HasLen, 1)
+	v, ok = ret["aborted_clients"]
+	c.Assert(ok, IsTrue)
+	c.Assert(v, Equals, "0")
+}
+
 func (p *testShowSuit) TestIssue540(c *C) {
 	// Show variables where variable_name="time_zone"
 	pln := &plans.ShowPlan{
--- a/session.go
+++ b/session.go
@ -265,9 +265,9 @@ func (s *session) ExecRestrictedSQL(ctx context.Context, sql string) (rset.Recor
 	return rs, errors.Trace(err)
 }

-// GetGlobalSysVar implements RestrictedSQLExecutor.GetGlobalSysVar interface.
-func (s *session) GetGlobalSysVar(ctx context.Context, name string) (string, error) {
-	sql := fmt.Sprintf(`SELECT VARIABLE_VALUE FROM %s.%s WHERE VARIABLE_NAME="%s";`, mysql.SystemDB, mysql.GlobalVariablesTable, name)
+// getExecRet executes restricted sql and the result is one column.
+// It returns a string value.
+func (s *session) getExecRet(ctx context.Context, sql string) (string, error) {
 	rs, err := s.ExecRestrictedSQL(ctx, sql)
 	if err != nil {
 		return "", errors.Trace(err)
@ -278,7 +278,7 @@ func (s *session) GetGlobalSysVar(ctx context.Context, name string) (string, err
 		return "", errors.Trace(err)
 	}
 	if row == nil {
-		return "", fmt.Errorf("Unknown sys var: %s", name)
+		return "", terror.ExecResultIsEmpty
 	}
 	value, err := types.ToString(row.Data[0])
 	if err != nil {
@ -287,7 +287,44 @@ func (s *session) GetGlobalSysVar(ctx context.Context, name string) (string, err
 	return value, nil
 }

-// SetGlobalSysVar implements RestrictedSQLExecutor.SetGlobalSysVar interface.
+// GetGlobalStatusVar implements GlobalVarAccessor.GetGlobalStatusVar interface.
+func (s *session) GetGlobalStatusVar(ctx context.Context, name string) (string, error) {
+	// TODO: get global status variables from store.
+	v := variable.GetStatusVar(name)
+	if v == nil {
+		return "", terror.UnknownStatusVar.Gen("unknown status variable:%s", name)
+	}
+
+	return v.Value, nil
+}
+
+// SetGlobalStatusVar implements GlobalVarAccessor.SetGlobalStatusVar interface.
+func (s *session) SetGlobalStatusVar(ctx context.Context, name string, value string) error {
+	// TODO: set global status variables from store.
+	v := variable.GetStatusVar(name)
+	if v == nil {
+		return terror.UnknownStatusVar.Gen("unknown status variable:%s", name)
+	}
+	v.Value = value
+
+	return nil
+}
+
+// GetGlobalSysVar implements GlobalVarAccessor.GetGlobalSysVar interface.
+func (s *session) GetGlobalSysVar(ctx context.Context, name string) (string, error) {
+	sql := fmt.Sprintf(`SELECT VARIABLE_VALUE FROM %s.%s WHERE VARIABLE_NAME="%s";`, mysql.SystemDB, mysql.GlobalVariablesTable, name)
+	sysVar, err := s.getExecRet(ctx, sql)
+	if err != nil {
+		if terror.ExecResultIsEmpty.Equal(err) {
+			return "", terror.ExecResultIsEmpty.Gen("unknown sys variable:%s", name)
+		}
+		return "", errors.Trace(err)
+	}
+
+	return sysVar, nil
+}
+
+// SetGlobalSysVar implements GlobalVarAccessor.SetGlobalSysVar interface.
 func (s *session) SetGlobalSysVar(ctx context.Context, name string, value string) error {
 	sql := fmt.Sprintf(`UPDATE  %s.%s SET VARIABLE_VALUE="%s" WHERE VARIABLE_NAME="%s";`, mysql.SystemDB, mysql.GlobalVariablesTable, value, strings.ToLower(name))
 	_, err := s.ExecRestrictedSQL(ctx, sql)
@ -545,8 +582,8 @@ func CreateSession(store kv.Storage) (Session, error) {
 	variable.BindSessionVars(s)
 	variable.GetSessionVars(s).SetStatusFlag(mysql.ServerStatusAutocommit, true)

-	// session implements variable.GlobalSysVarAccessor. Bind it to ctx.
-	variable.BindGlobalSysVarAccessor(s, s)
+	// session implements variable.GlobalVarAccessor. Bind it to ctx.
+	variable.BindGlobalVarAccessor(s, s)

 	// session implements autocommit.Checker. Bind it to ctx
 	autocommit.BindAutocommitChecker(s, s)
--- a/sessionctx/variable/session.go
+++ b/sessionctx/variable/session.go
@ -23,6 +23,8 @@ type SessionVars struct {
 	Users map[string]string
 	// system variables
 	Systems map[string]string
+	// status variables
+	StatusVars map[string]string
 	// prepared statement
 	PreparedStmts map[string]interface{}
 	// prepared statement auto increment id
@ -58,6 +60,7 @@ func BindSessionVars(ctx context.Context) {
 	v := &SessionVars{
 		Users:         make(map[string]string),
 		Systems:       make(map[string]string),
+		StatusVars:    make(map[string]string),
 		PreparedStmts: make(map[string]interface{}),
 	}

--- a/sessionctx/variable/statusvar.go
+++ b/sessionctx/variable/statusvar.go
@ -0,0 +1,391 @@
+// Copyright 2015 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package variable
+
+import (
+	"strings"
+)
+
+// StatusVars is global status vars map.
+var StatusVars map[string]*SysVar
+
+// GetStatusVar returns status var infomation for name.
+func GetStatusVar(name string) *SysVar {
+	name = strings.ToLower(name)
+	return StatusVars[name]
+}
+
+func init() {
+	StatusVars = make(map[string]*SysVar)
+	for _, v := range defaultStatusVars {
+		StatusVars[v.Name] = v
+	}
+}
+
+var defaultStatusVars = []*SysVar{
+	{ScopeGlobal, "aborted_clients", "0"},
+	{ScopeGlobal, "binlog_cache_disk_use", "0"},
+	{ScopeGlobal, "binlog_cache_use", "0"},
+	{ScopeGlobal, "binlog_stmt_cache_disk_use", "0"},
+	{ScopeGlobal, "binlog_stmt_cache_use", "0"},
+	{ScopeGlobal | ScopeSession, "bytes_received", "2262"},
+	{ScopeGlobal | ScopeSession, "bytes_sent", "106142"},
+	{ScopeGlobal | ScopeSession, "com_admin_commands", "0"},
+	{ScopeGlobal | ScopeSession, "com_assign_to_keycache", "0"},
+	{ScopeGlobal | ScopeSession, "com_alter_db", "0"},
+	{ScopeGlobal | ScopeSession, "com_alter_db_upgrade", "0"},
+	{ScopeGlobal | ScopeSession, "com_alter_event", "0"},
+	{ScopeGlobal | ScopeSession, "com_alter_function", "0"},
+	{ScopeGlobal | ScopeSession, "com_alter_procedure", "0"},
+	{ScopeGlobal | ScopeSession, "com_alter_server", "0"},
+	{ScopeGlobal | ScopeSession, "com_alter_table", "0"},
+	{ScopeGlobal | ScopeSession, "com_alter_tablespace", "0"},
+	{ScopeGlobal | ScopeSession, "com_alter_user", "0"},
+	{ScopeGlobal | ScopeSession, "com_analyze", "0"},
+	{ScopeGlobal | ScopeSession, "com_begin", "0"},
+	{ScopeGlobal | ScopeSession, "com_binlog", "0"},
+	{ScopeGlobal | ScopeSession, "com_call_procedure", "0"},
+	{ScopeGlobal | ScopeSession, "com_change_db", "2"},
+	{ScopeGlobal | ScopeSession, "com_change_master", "0"},
+	{ScopeGlobal | ScopeSession, "com_change_repl_filter", "0"},
+	{ScopeGlobal | ScopeSession, "com_check", "0"},
+	{ScopeGlobal | ScopeSession, "com_checksum", "0"},
+	{ScopeGlobal | ScopeSession, "com_commit", "0"},
+	{ScopeGlobal | ScopeSession, "com_create_db", "1"},
+	{ScopeGlobal | ScopeSession, "com_create_event", "0"},
+	{ScopeGlobal | ScopeSession, "com_create_function", "0"},
+	{ScopeGlobal | ScopeSession, "com_create_index", "0"},
+	{ScopeGlobal | ScopeSession, "com_create_procedure", "0"},
+	{ScopeGlobal | ScopeSession, "com_create_server", "0"},
+	{ScopeGlobal | ScopeSession, "com_create_table", "1"},
+	{ScopeGlobal | ScopeSession, "com_create_trigger", "0"},
+	{ScopeGlobal | ScopeSession, "com_create_udf", "0"},
+	{ScopeGlobal | ScopeSession, "com_create_user", "0"},
+	{ScopeGlobal | ScopeSession, "com_create_view", "0"},
+	{ScopeGlobal | ScopeSession, "com_dealloc_sql", "0"},
+	{ScopeGlobal | ScopeSession, "com_delete", "0"},
+	{ScopeGlobal | ScopeSession, "com_delete_multi", "0"},
+	{ScopeGlobal | ScopeSession, "com_do", "0"},
+	{ScopeGlobal | ScopeSession, "com_drop_db", "0"},
+	{ScopeGlobal | ScopeSession, "com_drop_event", "0"},
+	{ScopeGlobal | ScopeSession, "com_drop_function", "0"},
+	{ScopeGlobal | ScopeSession, "com_drop_index", "0"},
+	{ScopeGlobal | ScopeSession, "com_drop_procedure", "0"},
+	{ScopeGlobal | ScopeSession, "com_drop_server", "0"},
+	{ScopeGlobal | ScopeSession, "com_drop_table", "0"},
+	{ScopeGlobal | ScopeSession, "com_drop_trigger", "0"},
+	{ScopeGlobal | ScopeSession, "com_drop_user", "0"},
+	{ScopeGlobal | ScopeSession, "com_drop_view", "0"},
+	{ScopeGlobal | ScopeSession, "com_empty_query", "0"},
+	{ScopeGlobal | ScopeSession, "com_execute_sql", "0"},
+	{ScopeGlobal | ScopeSession, "com_explain_other", "0"},
+	{ScopeGlobal | ScopeSession, "com_flush", "0"},
+	{ScopeGlobal | ScopeSession, "com_get_diagnostics", "0"},
+	{ScopeGlobal | ScopeSession, "com_grant", "0"},
+	{ScopeGlobal | ScopeSession, "com_ha_close", "0"},
+	{ScopeGlobal | ScopeSession, "com_ha_open", "0"},
+	{ScopeGlobal | ScopeSession, "com_ha_read", "0"},
+	{ScopeGlobal | ScopeSession, "com_help", "0"},
+	{ScopeGlobal | ScopeSession, "com_insert", "0"},
+	{ScopeGlobal | ScopeSession, "com_insert_select", "0"},
+	{ScopeGlobal | ScopeSession, "com_install_plugin", "0"},
+	{ScopeGlobal | ScopeSession, "com_kill", "0"},
+	{ScopeGlobal | ScopeSession, "com_load", "0"},
+	{ScopeGlobal | ScopeSession, "com_lock_tables", "0"},
+	{ScopeGlobal | ScopeSession, "com_optimize", "0"},
+	{ScopeGlobal | ScopeSession, "com_preload_keys", "0"},
+	{ScopeGlobal | ScopeSession, "com_prepare_sql", "0"},
+	{ScopeGlobal | ScopeSession, "com_purge", "0"},
+	{ScopeGlobal | ScopeSession, "com_purge_before_date", "0"},
+	{ScopeGlobal | ScopeSession, "com_release_savepoint", "0"},
+	{ScopeGlobal | ScopeSession, "com_rename_table", "0"},
+	{ScopeGlobal | ScopeSession, "com_rename_user", "0"},
+	{ScopeGlobal | ScopeSession, "com_repair", "0"},
+	{ScopeGlobal | ScopeSession, "com_replace", "0"},
+	{ScopeGlobal | ScopeSession, "com_replace_select", "0"},
+	{ScopeGlobal | ScopeSession, "com_reset", "0"},
+	{ScopeGlobal | ScopeSession, "com_resignal", "0"},
+	{ScopeGlobal | ScopeSession, "com_revoke", "0"},
+	{ScopeGlobal | ScopeSession, "com_revoke_all", "0"},
+	{ScopeGlobal | ScopeSession, "com_rollback", "0"},
+	{ScopeGlobal | ScopeSession, "com_rollback_to_savepoint", "0"},
+	{ScopeGlobal | ScopeSession, "com_savepoint", "0"},
+	{ScopeGlobal | ScopeSession, "com_select", "9"},
+	{ScopeGlobal | ScopeSession, "com_set_option", "0"},
+	{ScopeGlobal | ScopeSession, "com_signal", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_binlog_events", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_binlogs", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_charsets", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_collations", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_create_db", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_create_event", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_create_func", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_create_proc", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_create_table", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_create_trigger", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_databases", "1"},
+	{ScopeGlobal | ScopeSession, "com_show_engine_logs", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_engine_mutex", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_engine_status", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_events", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_errors", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_fields", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_function_code", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_function_status", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_grants", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_keys", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_master_status", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_open_tables", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_plugins", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_privileges", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_procedure_code", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_procedure_status", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_processlist", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_profile", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_profiles", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_relaylog_events", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_slave_hosts", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_slave_status", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_status", "25"},
+	{ScopeGlobal | ScopeSession, "com_show_storage_engines", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_table_status", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_tables", "2"},
+	{ScopeGlobal | ScopeSession, "com_show_triggers", "0"},
+	{ScopeGlobal | ScopeSession, "com_show_variables", "4"},
+	{ScopeGlobal | ScopeSession, "com_show_warnings", "2"},
+	{ScopeGlobal | ScopeSession, "com_show_create_user", "0"},
+	{ScopeGlobal | ScopeSession, "com_shutdown", "0"},
+	{ScopeGlobal | ScopeSession, "com_slave_start", "0"},
+	{ScopeGlobal | ScopeSession, "com_slave_stop", "0"},
+	{ScopeGlobal | ScopeSession, "com_group_replication_start", "0"},
+	{ScopeGlobal | ScopeSession, "com_group_replication_stop", "0"},
+	{ScopeGlobal | ScopeSession, "com_stmt_execute", "0"},
+	{ScopeGlobal | ScopeSession, "com_stmt_close", "0"},
+	{ScopeGlobal | ScopeSession, "com_stmt_fetch", "0"},
+	{ScopeGlobal | ScopeSession, "com_stmt_prepare", "0"},
+	{ScopeGlobal | ScopeSession, "com_stmt_reset", "0"},
+	{ScopeGlobal | ScopeSession, "com_stmt_send_long_data", "0"},
+	{ScopeGlobal | ScopeSession, "com_truncate", "0"},
+	{ScopeGlobal | ScopeSession, "com_uninstall_plugin", "0"},
+	{ScopeGlobal | ScopeSession, "com_unlock_tables", "0"},
+	{ScopeGlobal | ScopeSession, "com_update", "0"},
+	{ScopeGlobal | ScopeSession, "com_update_multi", "0"},
+	{ScopeGlobal | ScopeSession, "com_xa_commit", "0"},
+	{ScopeGlobal | ScopeSession, "com_xa_end", "0"},
+	{ScopeGlobal | ScopeSession, "com_xa_prepare", "0"},
+	{ScopeGlobal | ScopeSession, "com_xa_recover", "0"},
+	{ScopeGlobal | ScopeSession, "com_xa_rollback", "0"},
+	{ScopeGlobal | ScopeSession, "com_xa_start", "0"},
+	{ScopeGlobal | ScopeSession, "com_stmt_reprepare", "0"},
+	{ScopeSession, "compression", "off"},
+	{ScopeGlobal, "connection_errors_accept", "0"},
+	{ScopeGlobal, "connection_errors_internal", "0"},
+	{ScopeGlobal, "connection_errors_max_connections", "0"},
+	{ScopeGlobal, "connection_errors_peer_address", "0"},
+	{ScopeGlobal, "connection_errors_select", "0"},
+	{ScopeGlobal, "connection_errors_tcpwrap", "0"},
+	{ScopeGlobal, "connections", "3"},
+	{ScopeGlobal | ScopeSession, "created_tmp_disk_tables", "0"},
+	{ScopeGlobal, "created_tmp_files", "6"},
+	{ScopeGlobal | ScopeSession, "created_tmp_tables", "3"},
+	{ScopeGlobal, "delayed_errors", "0"},
+	{ScopeGlobal, "delayed_insert_threads", "0"},
+	{ScopeGlobal, "delayed_writes", "0"},
+	{ScopeGlobal, "flush_commands", "1"},
+	{ScopeGlobal | ScopeSession, "handler_commit", "5"},
+	{ScopeGlobal | ScopeSession, "handler_delete", "0"},
+	{ScopeGlobal | ScopeSession, "handler_discover", "0"},
+	{ScopeGlobal | ScopeSession, "handler_external_lock", "265"},
+	{ScopeGlobal | ScopeSession, "handler_mrr_init", "0"},
+	{ScopeGlobal | ScopeSession, "handler_prepare", "0"},
+	{ScopeGlobal | ScopeSession, "handler_read_first", "8"},
+	{ScopeGlobal | ScopeSession, "handler_read_key", "6"},
+	{ScopeGlobal | ScopeSession, "handler_read_last", "0"},
+	{ScopeGlobal | ScopeSession, "handler_read_next", "1"},
+	{ScopeGlobal | ScopeSession, "handler_read_prev", "0"},
+	{ScopeGlobal | ScopeSession, "handler_read_rnd", "0"},
+	{ScopeGlobal | ScopeSession, "handler_read_rnd_next", "7642"},
+	{ScopeGlobal | ScopeSession, "handler_rollback", "0"},
+	{ScopeGlobal | ScopeSession, "handler_savepoint", "0"},
+	{ScopeGlobal | ScopeSession, "handler_savepoint_rollback", "0"},
+	{ScopeGlobal | ScopeSession, "handler_update", "0"},
+	{ScopeGlobal | ScopeSession, "handler_write", "6"},
+	{ScopeGlobal, "innodb_buffer_pool_dump_status", "notstarted"},
+	{ScopeGlobal, "innodb_buffer_pool_load_status", "Bufferpool(s)loadcom"},
+	{ScopeGlobal, "innodb_buffer_pool_resize_status", "notstarted"},
+	{ScopeGlobal, "innodb_buffer_pool_pages_data", "440"},
+	{ScopeGlobal, "innodb_buffer_pool_bytes_data", "7208960"},
+	{ScopeGlobal, "innodb_buffer_pool_pages_dirty", "0"},
+	{ScopeGlobal, "innodb_buffer_pool_bytes_dirty", "0"},
+	{ScopeGlobal, "innodb_buffer_pool_pages_flushed", "54"},
+	{ScopeGlobal, "innodb_buffer_pool_pages_free", "7751"},
+	{ScopeGlobal, "innodb_buffer_pool_pages_misc", "0"},
+	{ScopeGlobal, "innodb_buffer_pool_pages_total", "8191"},
+	{ScopeGlobal, "innodb_buffer_pool_read_ahead_rnd", "0"},
+	{ScopeGlobal, "innodb_buffer_pool_read_ahead", "0"},
+	{ScopeGlobal, "innodb_buffer_pool_read_ahead_evicted", "0"},
+	{ScopeGlobal, "innodb_buffer_pool_read_requests", "1466"},
+	{ScopeGlobal, "innodb_buffer_pool_reads", "402"},
+	{ScopeGlobal, "innodb_buffer_pool_wait_free", "0"},
+	{ScopeGlobal, "innodb_buffer_pool_write_requests", "400"},
+	{ScopeGlobal, "innodb_data_fsyncs", "24"},
+	{ScopeGlobal, "innodb_data_pending_fsyncs", "0"},
+	{ScopeGlobal, "innodb_data_pending_reads", "0"},
+	{ScopeGlobal, "innodb_data_pending_writes", "0"},
+	{ScopeGlobal, "innodb_data_read", "6656512"},
+	{ScopeGlobal, "innodb_data_reads", "426"},
+	{ScopeGlobal, "innodb_data_writes", "84"},
+	{ScopeGlobal, "innodb_data_written", "1232384"},
+	{ScopeGlobal, "innodb_dblwr_pages_written", "20"},
+	{ScopeGlobal, "innodb_dblwr_writes", "2"},
+	{ScopeGlobal, "innodb_log_waits", "0"},
+	{ScopeGlobal, "innodb_log_write_requests", "14"},
+	{ScopeGlobal, "innodb_log_writes", "8"},
+	{ScopeGlobal, "innodb_os_log_fsyncs", "12"},
+	{ScopeGlobal, "innodb_os_log_pending_fsyncs", "0"},
+	{ScopeGlobal, "innodb_os_log_pending_writes", "0"},
+	{ScopeGlobal, "innodb_os_log_written", "17920"},
+	{ScopeGlobal, "innodb_page_size", "16384"},
+	{ScopeGlobal, "innodb_pages_created", "39"},
+	{ScopeGlobal, "innodb_pages_read", "401"},
+	{ScopeGlobal, "innodb_pages_written", "54"},
+	{ScopeGlobal, "innodb_row_lock_current_waits", "0"},
+	{ScopeGlobal, "innodb_row_lock_time", "0"},
+	{ScopeGlobal, "innodb_row_lock_time_avg", "0"},
+	{ScopeGlobal, "innodb_row_lock_time_max", "0"},
+	{ScopeGlobal, "innodb_row_lock_waits", "0"},
+	{ScopeGlobal, "innodb_rows_deleted", "0"},
+	{ScopeGlobal, "innodb_rows_inserted", "0"},
+	{ScopeGlobal, "innodb_rows_read", "8"},
+	{ScopeGlobal, "innodb_rows_updated", "0"},
+	{ScopeGlobal, "innodb_num_open_files", "17"},
+	{ScopeGlobal, "innodb_truncated_status_writes", "0"},
+	{ScopeGlobal, "innodb_available_undo_logs", "128"},
+	{ScopeSession, "last_query_cost", "104.799000"},
+	{ScopeSession, "last_query_partial_plans", "1"},
+	{ScopeGlobal, "key_blocks_not_flushed", "0"},
+	{ScopeGlobal, "key_blocks_unused", "6695"},
+	{ScopeGlobal, "key_blocks_used", "3"},
+	{ScopeGlobal, "key_read_requests", "6"},
+	{ScopeGlobal, "key_reads", "3"},
+	{ScopeGlobal, "key_write_requests", "0"},
+	{ScopeGlobal, "key_writes", "0"},
+	{ScopeGlobal | ScopeSession, "locked_connects", "0"},
+	{ScopeGlobal | ScopeSession, "max_execution_time_exceeded", "0"},
+	{ScopeGlobal | ScopeSession, "max_execution_time_set", "0"},
+	{ScopeGlobal | ScopeSession, "max_execution_time_set_failed", "0"},
+	{ScopeGlobal, "max_used_connections", "1"},
+	{ScopeGlobal, "max_used_connections_time", "2015-11-0902:49:42"},
+	{ScopeGlobal, "not_flushed_delayed_rows", "0"},
+	{ScopeGlobal, "ongoing_anonymous_transaction_count", "0"},
+	{ScopeGlobal, "open_files", "14"},
+	{ScopeGlobal, "open_streams", "0"},
+	{ScopeGlobal, "open_table_definitions", "105"},
+	{ScopeGlobal | ScopeSession, "Open_tables", "101"},
+	{ScopeGlobal, "opened_files", "142"},
+	{ScopeGlobal | ScopeSession, "opened_table_definitions", "106"},
+	{ScopeGlobal | ScopeSession, "opened_tables", "108"},
+	{ScopeGlobal, "performance_schema_accounts_lost", "0"},
+	{ScopeGlobal, "performance_schema_cond_classes_lost", "0"},
+	{ScopeGlobal, "performance_schema_cond_instances_lost", "0"},
+	{ScopeGlobal, "performance_schema_digest_lost", "0"},
+	{ScopeGlobal, "performance_schema_file_classes_lost", "0"},
+	{ScopeGlobal, "performance_schema_file_handles_lost", "0"},
+	{ScopeGlobal, "performance_schema_file_instances_lost", "0"},
+	{ScopeGlobal, "performance_schema_hosts_lost", "0"},
+	{ScopeGlobal, "performance_schema_index_stat_lost", "0"},
+	{ScopeGlobal, "performance_schema_locker_lost", "0"},
+	{ScopeGlobal, "performance_schema_memory_classes_lost", "0"},
+	{ScopeGlobal, "performance_schema_metadata_lock_lost", "0"},
+	{ScopeGlobal, "performance_schema_mutex_classes_lost", "0"},
+	{ScopeGlobal, "performance_schema_mutex_instances_lost", "0"},
+	{ScopeGlobal, "performance_schema_nested_statement_lost", "0"},
+	{ScopeGlobal, "performance_schema_prepared_statements_lost", "0"},
+	{ScopeGlobal, "performance_schema_program_lost", "0"},
+	{ScopeGlobal, "performance_schema_rwlock_classes_lost", "0"},
+	{ScopeGlobal, "performance_schema_rwlock_instances_lost", "0"},
+	{ScopeGlobal, "performance_schema_session_connect_attrs_lost", "0"},
+	{ScopeGlobal, "performance_schema_socket_classes_lost", "0"},
+	{ScopeGlobal, "performance_schema_socket_instances_lost", "0"},
+	{ScopeGlobal, "performance_schema_stage_classes_lost", "0"},
+	{ScopeGlobal, "performance_schema_statement_classes_lost", "0"},
+	{ScopeGlobal, "performance_schema_table_handles_lost", "0"},
+	{ScopeGlobal, "performance_schema_table_instances_lost", "0"},
+	{ScopeGlobal, "performance_schema_table_lock_stat_lost", "0"},
+	{ScopeGlobal, "performance_schema_thread_classes_lost", "0"},
+	{ScopeGlobal, "performance_schema_thread_instances_lost", "0"},
+	{ScopeGlobal, "performance_schema_users_lost", "0"},
+	{ScopeGlobal, "prepared_stmt_count", "0"},
+	{ScopeGlobal, "qcache_free_blocks", "1"},
+	{ScopeGlobal, "qcache_free_memory", "1031832"},
+	{ScopeGlobal, "qcache_hits", "0"},
+	{ScopeGlobal, "qcache_inserts", "0"},
+	{ScopeGlobal, "qcache_lowmem_prunes", "0"},
+	{ScopeGlobal, "qcache_not_cached", "5"},
+	{ScopeGlobal, "qcache_queries_in_cache", "0"},
+	{ScopeGlobal, "qcache_total_blocks", "1"},
+	{ScopeGlobal | ScopeSession, "queries", "56"},
+	{ScopeGlobal | ScopeSession, "questions", "54"},
+	{ScopeGlobal | ScopeSession, "select_full_join", "0"},
+	{ScopeGlobal | ScopeSession, "select_full_range_join", "0"},
+	{ScopeGlobal | ScopeSession, "select_range", "0"},
+	{ScopeGlobal | ScopeSession, "select_range_check", "0"},
+	{ScopeGlobal | ScopeSession, "select_scan", "24"},
+	{ScopeGlobal, "slave_open_temp_tables", "0"},
+	{ScopeGlobal | ScopeSession, "slow_launch_threads", "0"},
+	{ScopeGlobal | ScopeSession, "slow_queries", "0"},
+	{ScopeGlobal | ScopeSession, "sort_merge_passes", "0"},
+	{ScopeGlobal | ScopeSession, "sort_range", "0"},
+	{ScopeGlobal | ScopeSession, "sort_rows", "0"},
+	{ScopeGlobal | ScopeSession, "sort_scan", "0"},
+	{ScopeGlobal, "ssl_accept_renegotiates", "0"},
+	{ScopeGlobal, "ssl_accepts", "0"},
+	{ScopeGlobal, "ssl_callback_cache_hits", "0"},
+	{ScopeGlobal | ScopeSession, "ssl_cipher", ""},
+	{ScopeGlobal | ScopeSession, "ssl_cipher_list", ""},
+	{ScopeGlobal, "ssl_client_connects", "0"},
+	{ScopeGlobal, "ssl_connect_renegotiates", "0"},
+	{ScopeGlobal, "ssl_ctx_verify_depth", "0"},
+	{ScopeGlobal, "ssl_ctx_verify_mode", "0"},
+	{ScopeGlobal | ScopeSession, "Ssl_default_timeout", "0"},
+	{ScopeGlobal, "ssl_finished_accepts", "0"},
+	{ScopeGlobal, "ssl_finished_connects", "0"},
+	{ScopeGlobal | ScopeSession, "ssl_server_not_after", ""},
+	{ScopeGlobal | ScopeSession, "ssl_server_not_before", ""},
+	{ScopeGlobal, "ssl_session_cache_hits", "0"},
+	{ScopeGlobal, "ssl_session_cache_misses", "0"},
+	{ScopeGlobal, "ssl_session_cache_mode", "NONE"},
+	{ScopeGlobal, "ssl_session_cache_overflows", "0"},
+	{ScopeGlobal, "ssl_session_cache_size", "0"},
+	{ScopeGlobal, "ssl_session_cache_timeouts", "0"},
+	{ScopeGlobal | ScopeSession, "ssl_sessions_reused", "0"},
+	{ScopeGlobal, "ssl_used_session_cache_entries", "0"},
+	{ScopeGlobal | ScopeSession, "ssl_verify_depth", "0"},
+	{ScopeGlobal | ScopeSession, "ssl_verify_mode", "0"},
+	{ScopeGlobal | ScopeSession, "ssl_version", ""},
+	{ScopeGlobal, "table_locks_immediate", "123"},
+	{ScopeGlobal, "table_locks_waited", "0"},
+	{ScopeGlobal | ScopeSession, "table_open_cache_hits", "28"},
+	{ScopeGlobal | ScopeSession, "table_open_cache_misses", "108"},
+	{ScopeGlobal | ScopeSession, "table_open_cache_overflows", "0"},
+	{ScopeGlobal, "tc_log_max_pages_used", "0"},
+	{ScopeGlobal, "tc_log_page_size", "0"},
+	{ScopeGlobal, "tc_log_page_waits", "0"},
+	{ScopeGlobal, "threads_cached", "0"},
+	{ScopeGlobal, "threads_connected", "1"},
+	{ScopeGlobal, "threads_created", "1"},
+	{ScopeGlobal, "threads_running", "1"},
+	{ScopeGlobal, "uptime", "15998"},
+	{ScopeGlobal, "uptime_since_flush_status", "15998"},
+}
--- a/sessionctx/variable/statusvar_test.go
+++ b/sessionctx/variable/statusvar_test.go
@ -0,0 +1,31 @@
+// Copyright 2015 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package variable
+
+import (
+	. "github.com/pingcap/check"
+)
+
+var _ = Suite(&testStatusVarSuite{})
+
+type testStatusVarSuite struct {
+}
+
+func (*testStatusVarSuite) TestStatusVar(c *C) {
+	f := GetStatusVar("aborted_clients")
+	c.Assert(f, NotNil)
+
+	f = GetStatusVar("wrong-var-name")
+	c.Assert(f, IsNil)
+}
--- a/sessionctx/variable/sysvar.go
+++ b/sessionctx/variable/sysvar.go
@ -574,12 +574,16 @@ const (
 	CollationConnection = "collation_connection"
 )

-// GlobalSysVarAccessor is the interface for accessing global scope system variables.
-type GlobalSysVarAccessor interface {
+// GlobalVarAccessor is the interface for accessing global scope system and status variables.
+type GlobalVarAccessor interface {
 	// GetGlobalSysVar gets the global system variable value for name.
 	GetGlobalSysVar(ctx context.Context, name string) (string, error)
 	// SetGlobalSysVar sets the global system variable name to value.
 	SetGlobalSysVar(ctx context.Context, name string, value string) error
+	// GetGlobalStatusVar gets the global status variable value for name.
+	GetGlobalStatusVar(ctx context.Context, name string) (string, error)
+	// SetGlobalStatusVar sets the global status variable name to value.
+	SetGlobalStatusVar(ctx context.Context, name string, value string) error
 }

 // globalSysVarAccessorKeyType is a dummy type to avoid naming collision in context.
@ -592,14 +596,14 @@ func (k globalSysVarAccessorKeyType) String() string {

 const accessorKey globalSysVarAccessorKeyType = 0

-// BindGlobalSysVarAccessor binds global sysvar accessor to context.
-func BindGlobalSysVarAccessor(ctx context.Context, accessor GlobalSysVarAccessor) {
+// BindGlobalVarAccessor binds global var accessor to context.
+func BindGlobalVarAccessor(ctx context.Context, accessor GlobalVarAccessor) {
 	ctx.SetValue(accessorKey, accessor)
 }

-// GetGlobalSysVarAccessor gets accessor from ctx.
-func GetGlobalSysVarAccessor(ctx context.Context) GlobalSysVarAccessor {
-	v, ok := ctx.Value(accessorKey).(GlobalSysVarAccessor)
+// GetGlobalVarAccessor gets accessor from ctx.
+func GetGlobalVarAccessor(ctx context.Context) GlobalVarAccessor {
+	v, ok := ctx.Value(accessorKey).(GlobalVarAccessor)
 	if !ok {
 		panic("Miss global sysvar accessor")
 	}
--- a/stmt/stmt.go
+++ b/stmt/stmt.go
@ -55,6 +55,7 @@ const (
 	ShowWarnings
 	ShowCharset
 	ShowVariables
+	ShowStatus
 	ShowCollation
 	ShowCreateTable
 	ShowGrants
--- a/stmt/stmts/drop.go
+++ b/stmt/stmts/drop.go
@ -24,6 +24,8 @@ import (
 	"github.com/pingcap/tidb/context"
 	"github.com/pingcap/tidb/ddl"
 	"github.com/pingcap/tidb/model"
+	"github.com/pingcap/tidb/mysql"
+	"github.com/pingcap/tidb/privilege"
 	"github.com/pingcap/tidb/rset"
 	"github.com/pingcap/tidb/sessionctx"
 	"github.com/pingcap/tidb/stmt"
@ -108,10 +110,34 @@ func (s *DropTableStmt) SetText(text string) {
 // Exec implements the stmt.Statement Exec interface.
 func (s *DropTableStmt) Exec(ctx context.Context) (rset.Recordset, error) {
 	var notExistTables []string
+	is := sessionctx.GetDomain(ctx).InfoSchema()
 	for _, ti := range s.TableIdents {
-		err := sessionctx.GetDomain(ctx).DDL().DropTable(ctx, ti.Full(ctx))
-		// TODO: we should return special error for table not exist, checking "not exist" is not enough,
-		// because some other errors may contain this error string too.
+		fullti := ti.Full(ctx)
+		schema, ok := is.SchemaByName(fullti.Schema)
+		if !ok {
+			// TODO: we should return special error for table not exist, checking "not exist" is not enough,
+			// because some other errors may contain this error string too.
+			notExistTables = append(notExistTables, ti.String())
+			continue
+		}
+		tb, err := is.TableByName(fullti.Schema, fullti.Name)
+		if err != nil && strings.HasSuffix(err.Error(), "not exist") {
+			notExistTables = append(notExistTables, ti.String())
+			continue
+		} else if err != nil {
+			return nil, errors.Trace(err)
+		}
+		// Check Privilege
+		privChecker := privilege.GetPrivilegeChecker(ctx)
+		hasPriv, err := privChecker.Check(ctx, schema, tb.Meta(), mysql.DropPriv)
+		if err != nil {
+			return nil, errors.Trace(err)
+		}
+		if !hasPriv {
+			return nil, errors.Errorf("You do not have the privilege to drop table %s.%s.", ti.Schema, ti.Name)
+		}
+
+		err = sessionctx.GetDomain(ctx).DDL().DropTable(ctx, fullti)
 		if terror.ErrorEqual(err, ddl.ErrNotExists) || terror.DatabaseNotExists.Equal(err) {
 			notExistTables = append(notExistTables, ti.String())
 		} else if err != nil {
--- a/stmt/stmts/set.go
+++ b/stmt/stmts/set.go
@ -100,7 +100,7 @@ func (s *SetStmt) Exec(ctx context.Context) (_ rset.Recordset, err error) {
 	log.Debug("Set sys/user variables")

 	sessionVars := variable.GetSessionVars(ctx)
-	globalVars := variable.GetGlobalSysVarAccessor(ctx)
+	globalVars := variable.GetGlobalVarAccessor(ctx)
 	for _, v := range s.Variables {
 		// Variable is case insensitive, we use lower case.
 		name := strings.ToLower(v.Name)
--- a/store/localstore/kv_test.go
+++ b/store/localstore/kv_test.go
@ -451,7 +451,8 @@ func (s *testKVSuite) TestConditionIfNotExist(c *C) {
 		}()
 	}
 	wg.Wait()
-	c.Assert(success, Greater, int64(1))
+	// At least one txn can success.
+	c.Assert(success, Greater, int64(0))

 	// Clean up
 	txn, err := s.s.Begin()
--- a/terror/terror.go
+++ b/terror/terror.go
@ -28,6 +28,10 @@ var (

 	CommitNotInTransaction   = ClassExecutor.New(CodeCommitNotInTransaction, "commit not in transaction")
 	RollbackNotInTransaction = ClassExecutor.New(CodeRollbackNotInTransaction, "rollback not in transaction")
+	ExecResultIsEmpty        = ClassExecutor.New(CodeExecResultIsEmpty, "exec result is empty")
+
+	UnknownStatusVar = ClassVariable.New(CodeUnknownStatusVar, "unknown status variable")
+	UnknownSystemVar = ClassVariable.New(CodeUnknownSystemVar, "unknown system variable")
 )

 // ErrCode represents a specific error type in a error class.
@ -44,6 +48,7 @@ const (
 const (
 	CodeCommitNotInTransaction ErrCode = iota + 1
 	CodeRollbackNotInTransaction
+	CodeExecResultIsEmpty
 )

 // KV error codes.
@ -52,6 +57,12 @@ const (
 	CodeNoDataForHandle
 )

+// Variable error codes.
+const (
+	CodeUnknownStatusVar ErrCode = iota + 1
+	CodeUnknownSystemVar
+)
+
 // ErrClass represents a class of errors.
 type ErrClass int

@ -63,6 +74,7 @@ const (
 	ClassExecutor
 	ClassKV
 	ClassServer
+	ClassVariable
 	// Add more as needed.
 )

--- a/util/mock/context.go
+++ b/util/mock/context.go
@ -16,11 +16,11 @@ package mock

 import (
 	"fmt"
-	"strings"

 	"github.com/pingcap/tidb/context"
 	"github.com/pingcap/tidb/kv"
 	"github.com/pingcap/tidb/sessionctx/variable"
+	"github.com/pingcap/tidb/terror"
 )

 var _ context.Context = (*Context)(nil)
@ -57,22 +57,39 @@ func (c *Context) FinishTxn(rollback bool) error {
 	return nil
 }

-// GetGlobalSysVar implements GlobalSysVarAccessor GetGlobalSysVar interface.
-func (c *Context) GetGlobalSysVar(ctx context.Context, name string) (string, error) {
-	sysvars := variable.SysVars
-	v, ok := sysvars[strings.ToLower(name)]
-	if !ok {
-		return "", nil
+// GetGlobalStatusVar implements GlobalVarAccessor GetGlobalStatusVar interface.
+func (c *Context) GetGlobalStatusVar(ctx context.Context, name string) (string, error) {
+	v := variable.GetStatusVar(name)
+	if v == nil {
+		return "", terror.UnknownStatusVar.Gen("unknown status variable: %s", name)
 	}
 	return v.Value, nil
 }

-// SetGlobalSysVar implements GlobalSysVarAccessor SetGlobalSysVar interface.
+// SetGlobalStatusVar implements GlobalVarAccessor SetGlobalStatusVar interface.
+func (c *Context) SetGlobalStatusVar(ctx context.Context, name string, value string) error {
+	v := variable.GetStatusVar(name)
+	if v == nil {
+		return terror.UnknownStatusVar.Gen("unknown status variable: %s", name)
+	}
+	v.Value = value
+	return nil
+}
+
+// GetGlobalSysVar implements GlobalVarAccessor GetGlobalSysVar interface.
+func (c *Context) GetGlobalSysVar(ctx context.Context, name string) (string, error) {
+	v := variable.GetSysVar(name)
+	if v == nil {
+		return "", terror.UnknownSystemVar.Gen("unknown sys variable: %s", name)
+	}
+	return v.Value, nil
+}
+
+// SetGlobalSysVar implements GlobalVarAccessor SetGlobalSysVar interface.
 func (c *Context) SetGlobalSysVar(ctx context.Context, name string, value string) error {
-	sysvars := variable.SysVars
-	v, ok := sysvars[strings.ToLower(name)]
-	if !ok {
-		return fmt.Errorf("Unknown sys var: %s", name)
+	v := variable.GetSysVar(name)
+	if v == nil {
+		return terror.UnknownSystemVar.Gen("unknown sys variable: %s", name)
 	}
 	v.Value = value
 	return nil
--- a/util/types/helper.go
+++ b/util/types/helper.go
@ -21,19 +21,11 @@ import (
 // RoundFloat uses default rounding mode, see http://www.gnu.org/software/libc/manual/html_node/Rounding.html
 // so we will choose the even number if the result is midway between two representable value.
 // e.g, 1.5 -> 2, 2.5 -> 2.
-func RoundFloat(val float64) float64 {
-	v, frac := math.Modf(val)
-	if val >= 0.0 {
-		if frac > 0.5 || (frac == 0.5 && uint64(v)%2 != 0) {
-			v += 1.0
-		}
-	} else {
-		if frac < -0.5 || (frac == -0.5 && uint64(v)%2 != 0) {
-			v -= 1.0
-		}
+func RoundFloat(f float64) float64 {
+	if math.Remainder(f, 1.0) < 0 {
+		return math.Ceil(f)
 	}
-
-	return v
+	return math.Floor(f)
 }

 func getMaxFloat(flen int, decimal int) float64 {