Merge branch 'master' into yiding/opt-trace

Author: winoros

.gitignore

@@ -2,6 +2,4 @@ bin/
 y.go
 *.output
 .idea/
-go.mod
-go.sum
 coverage.txt

README.md

@@ -7,6 +7,33 @@ TiDB SQL Parser
 
 ## How to use it
 
+```go
+import (
+	"fmt"
+	"github.com/pingcap/parser"
+	_ "github.com/pingcap/tidb/types/parser_driver"
+)
+
+// This example show how to parse a text sql into ast.
+func example() {
+
+	// 0. make sure import parser_driver implemented by TiDB(user also can implement own driver by self).
+	// and add `import _ "github.com/pingcap/tidb/types/parser_driver"` in the head of file.
+
+	// 1. Create a parser. The parser is NOT goroutine safe and should
+	// not be shared among multiple goroutines. However, parser is also
+	// heavy, so each goroutine should reuse its own local instance if
+	// possible.
+	p := parser.New()
+
+	// 2. Parse a text SQL into AST([]ast.StmtNode).
+	stmtNodes, _, err := p.Parse("select * from tbl where id = 1", "", "")
+
+	// 3. Use AST to do cool things.
+	fmt.Println(stmtNodes[0], err)
+}
+```
+
 See [https://godoc.org/github.com/pingcap/parser](https://godoc.org/github.com/pingcap/parser)
 
 ## How to update parser for TiDB

ast/advisor.go

@@ -0,0 +1,80 @@
+// Copyright 2019 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 ast
+
+import (
+	. "github.com/pingcap/parser/format"
+)
+
+var _ StmtNode = &IndexAdviseStmt{}
+
+// IndexAdviseStmt is used to advise indexes
+type IndexAdviseStmt struct {
+	stmtNode
+
+	IsLocal     bool
+	Path        string
+	MaxMinutes  uint64
+	MaxIndexNum *MaxIndexNumClause
+	LinesInfo   *LinesClause
+}
+
+// Restore implements Node Accept interface.
+func (n *IndexAdviseStmt) Restore(ctx *RestoreCtx) error {
+	ctx.WriteKeyWord("INDEX ADVISE ")
+	if n.IsLocal {
+		ctx.WriteKeyWord("LOCAL ")
+	}
+	ctx.WriteKeyWord("INFILE ")
+	ctx.WriteString(n.Path)
+	if n.MaxMinutes != UnspecifiedSize {
+		ctx.WriteKeyWord(" MAX_MINUTES ")
+		ctx.WritePlainf("%d", n.MaxMinutes)
+	}
+	if n.MaxIndexNum != nil {
+		n.MaxIndexNum.Restore(ctx)
+	}
+	n.LinesInfo.Restore(ctx)
+	return nil
+}
+
+// Accept implements Node Accept interface.
+func (n *IndexAdviseStmt) Accept(v Visitor) (Node, bool) {
+	newNode, skipChildren := v.Enter(n)
+	if skipChildren {
+		return v.Leave(newNode)
+	}
+	n = newNode.(*IndexAdviseStmt)
+	return v.Leave(n)
+}
+
+// MaxIndexNumClause represents 'maximum number of indexes' clause in index advise statement.
+type MaxIndexNumClause struct {
+	PerTable uint64
+	PerDB    uint64
+}
+
+// Restore for max index num clause
+func (n *MaxIndexNumClause) Restore(ctx *RestoreCtx) error {
+	ctx.WriteKeyWord(" MAX_IDXNUM")
+	if n.PerTable != UnspecifiedSize {
+		ctx.WriteKeyWord(" PER_TABLE ")
+		ctx.WritePlainf("%d", n.PerTable)
+	}
+	if n.PerDB != UnspecifiedSize {
+		ctx.WriteKeyWord(" PER_DB ")
+		ctx.WritePlainf("%d", n.PerDB)
+	}
+	return nil
+}