forked from pingcap/tidb
/
explain.go
76 lines (64 loc) · 1.96 KB
/
explain.go
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// 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 stmts
import (
"github.com/pingcap/tidb/context"
"github.com/pingcap/tidb/plan/plans"
"github.com/pingcap/tidb/rset"
"github.com/pingcap/tidb/rset/rsets"
"github.com/pingcap/tidb/stmt"
"github.com/pingcap/tidb/util/format"
)
var _ stmt.Statement = (*ExplainStmt)(nil)
// ExplainStmt is a statement to provide information about how is SQL statement executed
// or get columns information in a table.
// See: https://dev.mysql.com/doc/refman/5.7/en/explain.html
type ExplainStmt struct {
S stmt.Statement
Text string
}
// Explain implements the stmt.Statement Explain interface.
func (s *ExplainStmt) Explain(ctx context.Context, w format.Formatter) {
if x, ok := s.S.(*ShowStmt); ok {
x.SetText(s.Text)
x.Explain(ctx, w)
return
}
for {
x, ok := s.S.(*ExplainStmt)
if !ok {
s.S.Explain(ctx, w)
return
}
s = x
}
}
// IsDDL implements the stmt.Statement IsDDL interface.
func (s *ExplainStmt) IsDDL() bool {
return false
}
// OriginText implements the stmt.Statement OriginText interface.
func (s *ExplainStmt) OriginText() string {
return s.Text
}
// SetText implements the stmt.Statement SetText interface.
func (s *ExplainStmt) SetText(text string) {
s.Text = text
}
// Exec implements the stmt.Statement Exec interface.
func (s *ExplainStmt) Exec(ctx context.Context) (_ rset.Recordset, err error) {
if v, ok := s.S.(*ShowStmt); ok {
return v.Exec(ctx)
}
return rsets.Recordset{Ctx: ctx, Plan: &plans.ExplainDefaultPlan{S: s.S}}, nil
}