*: Implement show variables stmt/rset/plan

TODO: add test cases
liqingrikeiikyeong · Sep 10, 2015 · 20cf24f · 20cf24f
1 parent 288fc4b
commit 20cf24f
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Showing 4 changed files with 71 additions and 30 deletions.
diff --git a/parser/parser.y b/parser/parser.y
@@ -329,6 +329,7 @@ import (
 	Function		"function expr"
 	FunctionCall		"function call post part"
 	FunctionCallArgList	"function call optional argument list"
+	GlobalScope		"The scope of variable"
 	GroupByClause		"GROUP BY clause"
 	GroupByList		"GROUP BY list"
 	HavingClause		"HAVING clause"
@@ -422,7 +423,6 @@ import (
 	VariableAssignment	"set variable value"
 	VariableAssignmentList	"set variable value list"
 	Variable		"User or system variable"
-	VariableScope		"The scope of variable"
 	WhereClause		"WHERE clause"
 	WhereClauseOptional	"Optinal WHERE clause"
 
@@ -2650,34 +2650,36 @@ ShowStmt:
 	{
 		$$ = &stmts.ShowStmt{Target: stmt.ShowWarnings}
 	}
-|	"SHOW" VariableScope "VARIABLES"
+// See: https://dev.mysql.com/doc/refman/5.7/en/show-variables.html
+// TODO: Support show variables with where clause. 
+|	"SHOW" GlobalScope "VARIABLES"
 	{
 		$$ = &stmts.ShowStmt{
 			Target: stmt.ShowVariables,
-			VarScope: $2.(int),
+			GlobalScope: $2.(bool),
 		}
 
 	}
-|	"SHOW" VariableScope "VARIABLES" "LIKE" PrimaryExpression
+|	"SHOW" GlobalScope "VARIABLES" "LIKE" PrimaryExpression
 	{
 		$$ = &stmts.ShowStmt{
 			Target: stmt.ShowVariables,
-			VarScope: $2.(int),
+			GlobalScope: $2.(bool),
 			Pattern:  &expressions.PatternLike{Pattern: $5.(expression.Expression)},
 		}
 	}
 
-VariableScope:
+GlobalScope:
 	{
-		$$ = stmt.SessionScope	
+		$$ = false	
 	}
 |	"GLOBAL"
 	{
-		$$ = stmt.GlobalScope	
+		$$ = true	
 	}
 |	"SESSION" 
 	{
-		$$ = stmt.SessionScope	
+		$$ = false	
 	}
 
 OptFull:

diff --git a/plan/plans/show.go b/plan/plans/show.go
@@ -22,10 +22,12 @@ import (
 	"github.com/pingcap/tidb/column"
 	"github.com/pingcap/tidb/context"
 	"github.com/pingcap/tidb/expression"
+	"github.com/pingcap/tidb/expression/expressions"
 	"github.com/pingcap/tidb/field"
 	"github.com/pingcap/tidb/model"
 	"github.com/pingcap/tidb/plan"
 	"github.com/pingcap/tidb/sessionctx"
+	"github.com/pingcap/tidb/sessionctx/variable"
 	"github.com/pingcap/tidb/stmt"
 	"github.com/pingcap/tidb/util/charset"
 	"github.com/pingcap/tidb/util/format"
@@ -43,6 +45,9 @@ type ShowPlan struct {
 	ColumnName string
 	Flag       int
 	Full       bool
+	// Used by SHOW VARIABLES
+	GlobalScope bool
+	Pattern     expression.Expression
 }
 
 func (s *ShowPlan) isColOK(c *column.Col) bool {
@@ -144,6 +149,32 @@ func (s *ShowPlan) Do(ctx context.Context, f plan.RowIterFunc) (err error) {
 			row := []interface{}{desc.Name, desc.Desc, desc.DefaultCollation, desc.Maxlen}
 			f(0, row)
 		}
+	case stmt.ShowVariables:
+		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 {
+					return errors.Errorf("Like should be a PatternLike expression")
+				}
+				p.Expr = expressions.Value{Val: v.Name}
+				r, err := p.Eval(ctx, nil)
+				if err != nil {
+					return errors.Trace(err)
+				}
+				match, ok := r.(bool)
+				if !ok {
+					return errors.Errorf("Eval like pattern error")
+				}
+				if !match {
+					continue
+				}
+			}
+			row := []interface{}{v.Name, v.Value}
+			f(0, row)
+		}
 	}
 	return nil
 }
@@ -170,8 +201,9 @@ func (s *ShowPlan) GetFields() []*field.ResultField {
 		names = []string{"Level", "Code", "Message"}
 	case stmt.ShowCharset:
 		names = []string{"Charset", "Description", "Default collation", "Maxlen"}
+	case stmt.ShowVariables:
+		names = []string{"Variable_name", "Value"}
 	}
-
 	fields := make([]*field.ResultField, 0, len(names))
 	for _, name := range names {
 		fields = append(fields, &field.ResultField{Name: name})

diff --git a/rset/rsets/show.go b/rset/rsets/show.go
@@ -15,6 +15,7 @@ package rsets
 
 import (
 	"github.com/pingcap/tidb/context"
+	"github.com/pingcap/tidb/expression"
 	"github.com/pingcap/tidb/plan"
 	"github.com/pingcap/tidb/plan/plans"
 	"github.com/pingcap/tidb/sessionctx/db"
@@ -26,23 +27,27 @@ var (
 
 // ShowRset is record set to show.
 type ShowRset struct {
-	Target     int
-	DBName     string
-	TableName  string
-	ColumnName string
-	Flag       int
-	Full       bool
+	Target      int
+	DBName      string
+	TableName   string
+	ColumnName  string
+	Flag        int
+	Full        bool
+	GlobalScope bool
+	Pattern     expression.Expression
 }
 
 // Plan gets ShowPlan.
 func (r *ShowRset) Plan(ctx context.Context) (plan.Plan, error) {
 	return &plans.ShowPlan{
-		Target:     r.Target,
-		DBName:     r.getDBName(ctx),
-		TableName:  r.TableName,
-		ColumnName: r.ColumnName,
-		Flag:       r.Flag,
-		Full:       r.Full,
+		Target:      r.Target,
+		DBName:      r.getDBName(ctx),
+		TableName:   r.TableName,
+		ColumnName:  r.ColumnName,
+		Flag:        r.Flag,
+		Full:        r.Full,
+		GlobalScope: r.GlobalScope,
+		Pattern:     r.Pattern,
 	}, nil
 }
 

diff --git a/stmt/stmts/show.go b/stmt/stmts/show.go
@@ -37,8 +37,8 @@ type ShowStmt struct {
 	Full       bool
 
 	// Used by show variables
-	VarScope int
-	Pattern  expression.Expression
+	GlobalScope bool
+	Pattern     expression.Expression
 
 	Text string
 }
@@ -68,12 +68,14 @@ func (s *ShowStmt) Exec(ctx context.Context) (_ rset.Recordset, err error) {
 	// TODO: finish this
 	log.Debug("Exec Show Stmt")
 	sr := &rsets.ShowRset{
-		Target:     s.Target,
-		DBName:     s.DBName,
-		TableName:  s.TableIdent.Name.O,
-		ColumnName: s.ColumnName,
-		Flag:       s.Flag,
-		Full:       s.Full,
+		Target:      s.Target,
+		DBName:      s.DBName,
+		TableName:   s.TableIdent.Name.O,
+		ColumnName:  s.ColumnName,
+		Flag:        s.Flag,
+		Full:        s.Full,
+		GlobalScope: s.GlobalScope,
+		Pattern:     s.Pattern,
 	}
 
 	r, err := sr.Plan(ctx)