plans: Add test case for show variables

Add test case for show variables

plan/plans/show.go

@@ -66,8 +66,6 @@ func (s *ShowPlan) isColOK(c *column.Col) bool {
 
 // Do implements plan.Plan Do interface.
 func (s *ShowPlan) Do(ctx context.Context, f plan.RowIterFunc) (err error) {
-	is := sessionctx.GetDomain(ctx).InfoSchema()
-	dbName := model.NewCIStr(s.DBName)
 	switch s.Target {
 	case stmt.ShowEngines:
 		f(0, []interface{}{"InnoDB", "DEFAULT", "Supports transactions, row-level locking, and foreign keys", "YES", "YES", "YES"})
@@ -81,7 +79,8 @@ func (s *ShowPlan) Do(ctx context.Context, f plan.RowIterFunc) (err error) {
 			f(0, []interface{}{d})
 		}
 	case stmt.ShowTables:
-
+		is := sessionctx.GetDomain(ctx).InfoSchema()
+		dbName := model.NewCIStr(s.DBName)
 		if !is.SchemaExists(dbName) {
 			return errors.Errorf("Can not find DB: %s", dbName)
 		}
@@ -98,6 +97,8 @@ func (s *ShowPlan) Do(ctx context.Context, f plan.RowIterFunc) (err error) {
 			f(0, []interface{}{v})
 		}
 	case stmt.ShowColumns:
+		is := sessionctx.GetDomain(ctx).InfoSchema()
+		dbName := model.NewCIStr(s.DBName)
 		if !is.SchemaExists(dbName) {
 			return errors.Errorf("Can not find DB: %s", dbName)
 		}
@@ -150,10 +151,8 @@ func (s *ShowPlan) Do(ctx context.Context, f plan.RowIterFunc) (err error) {
 			f(0, row)
 		}
 	case stmt.ShowVariables:
+		sessionVars := variable.GetSessionVars(ctx)
 		for _, v := range variable.SysVars {
-			if s.GlobalScope != (v.Scope == variable.ScopeGlobal) {
-				continue
-			}
 			if s.Pattern != nil {
 				p, ok := s.Pattern.(*expressions.PatternLike)
 				if !ok {
@@ -172,7 +171,15 @@ func (s *ShowPlan) Do(ctx context.Context, f plan.RowIterFunc) (err error) {
 					continue
 				}
 			}
-			row := []interface{}{v.Name, v.Value}
+			value := v.Value
+			if !s.GlobalScope {
+				// Try to get Session Scope variable value
+				sv, ok := sessionVars.Systems[v.Name]
+				if ok {
+					value = sv
+				}
+			}
+			row := []interface{}{v.Name, value}
 			f(0, row)
 		}
 	}

plan/plans/show_test.go

@@ -11,4 +11,103 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package plans
+package plans_test
+
+import (
+	"fmt"
+
+	. "github.com/pingcap/check"
+	"github.com/pingcap/tidb"
+	"github.com/pingcap/tidb/expression/expressions"
+	"github.com/pingcap/tidb/kv"
+	"github.com/pingcap/tidb/plan/plans"
+	"github.com/pingcap/tidb/sessionctx/variable"
+	"github.com/pingcap/tidb/stmt"
+)
+
+type testShowSuit struct {
+	txn  kv.Transaction
+	vars map[string]interface{}
+}
+
+// implement Context interface
+func (p *testShowSuit) GetTxn(forceNew bool) (kv.Transaction, error) { return p.txn, nil }
+
+func (p *testShowSuit) FinishTxn(rollback bool) error { return nil }
+
+// SetValue saves a value associated with this context for key
+func (p *testShowSuit) SetValue(key fmt.Stringer, value interface{}) {
+	p.vars[key.String()] = value
+}
+
+// Value returns the value associated with this context for key
+func (p *testShowSuit) Value(key fmt.Stringer) interface{} {
+	return p.vars[key.String()]
+}
+
+// ClearValue clears the value associated with this context for key
+func (p *testShowSuit) ClearValue(key fmt.Stringer) {}
+
+var _ = Suite(&testShowSuit{})
+
+func (p *testShowSuit) SetUpSuite(c *C) {
+	var err error
+	store, err = tidb.NewStore(tidb.EngineGoLevelDBMemory)
+	c.Assert(err, IsNil)
+	p.vars = map[string]interface{}{}
+	p.txn, _ = store.Begin()
+	variable.BindSessionVars(p)
+}
+
+func (p *testShowSuit) TestShowVariables(c *C) {
+	pln := &plans.ShowPlan{
+		Target:      stmt.ShowVariables,
+		GlobalScope: true,
+		Pattern: &expressions.PatternLike{
+			Pattern: &expressions.Value{
+				Val: "character_set_results",
+			},
+		},
+	}
+	fls := pln.GetFields()
+	c.Assert(fls, HasLen, 2)
+	c.Assert(fls[0].Name, Equals, "Variable_name")
+	c.Assert(fls[1].Name, Equals, "Value")
+
+	sessionVars := variable.GetSessionVars(p)
+	ret := map[string]string{}
+	pln.Do(p, func(id interface{}, data []interface{}) (bool, error) {
+		ret[data[0].(string)] = data[1].(string)
+		return true, nil
+	})
+	c.Assert(ret, HasLen, 1)
+	v, ok := ret["character_set_results"]
+	c.Assert(ok, IsTrue)
+	c.Assert(v, Equals, "latin1")
+	// Set session variable to utf8
+	sessionVars.Systems["character_set_results"] = "utf8"
+	pln.Do(p, func(id interface{}, data []interface{}) (bool, error) {
+		ret[data[0].(string)] = data[1].(string)
+		return true, nil
+	})
+	c.Assert(ret, HasLen, 1)
+	v, ok = ret["character_set_results"]
+	c.Assert(ok, IsTrue)
+	// Show global varibale get latin1
+	c.Assert(v, Equals, "latin1")
+
+	pln.GlobalScope = false
+	pln.Do(p, func(id interface{}, data []interface{}) (bool, error) {
+		ret[data[0].(string)] = data[1].(string)
+		return true, nil
+	})
+	c.Assert(ret, HasLen, 1)
+	v, ok = ret["character_set_results"]
+	c.Assert(ok, IsTrue)
+	// Show session varibale get utf8
+	c.Assert(v, Equals, "utf8")
+}
+
+func (p *testShowSuit) TearDownSuite(c *C) {
+	p.txn.Commit()
+}

stmt/stmt.go

@@ -58,8 +58,9 @@ const (
 )
 
 const (
-	NoneScope = iota
-	SessionScope
+	// SessionScope shows varibales in session scope.
+	SessionScope = iota
+	// GlobalScope shows varibales in global scope.
 	GlobalScope
 )
 

stmt/stmts/show_test.go

@@ -37,4 +37,11 @@ func (s *testStmtSuite) TestShow(c *C) {
 	mf := newMockFormatter()
 	testStmt.Explain(nil, mf)
 	c.Assert(mf.Len(), Greater, 0)
+
+	testSQL = "SHOW VARIABLES LIKE 'character_set_results';"
+	stmtList, err = tidb.Compile(testSQL)
+	c.Assert(err, IsNil)
+	c.Assert(stmtList, HasLen, 1)
+	testStmt, ok = stmtList[0].(*stmts.ShowStmt)
+	c.Assert(ok, IsTrue)
 }