util.go

// Copyright 2018 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 diff

import (
	"math/rand"

	"github.com/pingcap/parser/model"
	"github.com/pingcap/tidb-tools/pkg/dbutil"
	"github.com/pingcap/tidb-tools/pkg/utils"
	"github.com/pingcap/tidb/types"
	log "github.com/sirupsen/logrus"
)

func equalStrings(str1, str2 []string) bool {
	if len(str1) != len(str2) {
		return false
	}
	for i := 0; i < len(str1); i++ {
		if str1[i] != str2[i] {
			return false
		}
	}
	return true
}

func removeColumns(tableInfo *model.TableInfo, columns []string) *model.TableInfo {
	if len(columns) == 0 {
		return tableInfo
	}

	removeColMap := utils.SliceToMap(columns)
	for i := 0; i < len(tableInfo.Indices); i++ {
		index := tableInfo.Indices[i]
		for j := 0; j < len(index.Columns); j++ {
			col := index.Columns[j]
			if _, ok := removeColMap[col.Name.O]; ok {
				index.Columns = append(index.Columns[:j], index.Columns[j+1:]...)
				j--
				if len(index.Columns) == 0 {
					tableInfo.Indices = append(tableInfo.Indices[:i], tableInfo.Indices[i+1:]...)
					i--
				}
			}
		}
	}

	for j := 0; j < len(tableInfo.Columns); j++ {
		col := tableInfo.Columns[j]
		if _, ok := removeColMap[col.Name.O]; ok {
			tableInfo.Columns = append(tableInfo.Columns[:j], tableInfo.Columns[j+1:]...)
			j--
		}
	}

	return tableInfo
}

func getColumnsFromIndex(index *model.IndexInfo, tableInfo *model.TableInfo) []*model.ColumnInfo {
	indexColumns := make([]*model.ColumnInfo, 0, len(index.Columns))
	for _, indexColumn := range index.Columns {
		for _, column := range tableInfo.Columns {
			if column.Name.O == indexColumn.Name.O {
				indexColumns = append(indexColumns, column)
			}
		}
	}

	return indexColumns
}

func getRandomN(total, num int) []int {
	if num > total {
		log.Warnf("the num %d is greater than total %d", num, total)
		num = total
	}

	totalArray := make([]int, 0, total)
	for i := 0; i < total; i++ {
		totalArray = append(totalArray, i)
	}

	for j := 0; j < num; j++ {
		r := j + rand.Intn(total-j)
		totalArray[j], totalArray[r] = totalArray[r], totalArray[j]
	}

	return totalArray[:num]
}

func needQuotes(ft types.FieldType) bool {
	return !(dbutil.IsNumberType(ft.Tp) || dbutil.IsFloatType(ft.Tp))
}