github.com/pingcap/tidb/parser@v0.0.0-20231013125129-93a834a6bf8d/mysql/util.go (about)

     1  // Copyright 2015 PingCAP, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package mysql
    15  
    16  type lengthAndDecimal struct {
    17  	length  int
    18  	decimal int
    19  }
    20  
    21  // defaultLengthAndDecimal provides default flen and decimal for fields
    22  // from CREATE TABLE when they are unspecified.
    23  var defaultLengthAndDecimal = map[byte]lengthAndDecimal{
    24  	TypeBit:        {1, 0},
    25  	TypeTiny:       {4, 0},
    26  	TypeShort:      {6, 0},
    27  	TypeInt24:      {9, 0},
    28  	TypeLong:       {11, 0},
    29  	TypeLonglong:   {20, 0},
    30  	TypeDouble:     {22, -1},
    31  	TypeFloat:      {12, -1},
    32  	TypeNewDecimal: {10, 0},
    33  	TypeDuration:   {10, 0},
    34  	TypeDate:       {10, 0},
    35  	TypeTimestamp:  {19, 0},
    36  	TypeDatetime:   {19, 0},
    37  	TypeYear:       {4, 0},
    38  	TypeString:     {1, 0},
    39  	TypeVarchar:    {5, 0},
    40  	TypeVarString:  {5, 0},
    41  	TypeTinyBlob:   {255, 0},
    42  	TypeBlob:       {65535, 0},
    43  	TypeMediumBlob: {16777215, 0},
    44  	TypeLongBlob:   {4294967295, 0},
    45  	TypeJSON:       {4294967295, 0},
    46  	TypeNull:       {0, 0},
    47  	TypeSet:        {-1, 0},
    48  	TypeEnum:       {-1, 0},
    49  }
    50  
    51  // IsIntegerType indicate whether tp is an integer type.
    52  func IsIntegerType(tp byte) bool {
    53  	switch tp {
    54  	case TypeTiny, TypeShort, TypeInt24, TypeLong, TypeLonglong:
    55  		return true
    56  	}
    57  	return false
    58  }
    59  
    60  // GetDefaultFieldLengthAndDecimal returns the default display length (flen) and decimal length for column.
    61  // Call this when no flen assigned in ddl.
    62  // or column value is calculated from an expression.
    63  // For example: "select count(*) from t;", the column type is int64 and flen in ResultField will be 21.
    64  // See https://dev.mysql.com/doc/refman/5.7/en/storage-requirements.html
    65  func GetDefaultFieldLengthAndDecimal(tp byte) (flen int, decimal int) {
    66  	val, ok := defaultLengthAndDecimal[tp]
    67  	if ok {
    68  		return val.length, val.decimal
    69  	}
    70  	return -1, -1
    71  }
    72  
    73  // defaultLengthAndDecimal provides default flen and decimal for fields
    74  // from CAST when they are unspecified.
    75  var defaultLengthAndDecimalForCast = map[byte]lengthAndDecimal{
    76  	TypeString:     {0, -1}, // flen & decimal differs.
    77  	TypeDate:       {10, 0},
    78  	TypeDatetime:   {19, 0},
    79  	TypeNewDecimal: {10, 0},
    80  	TypeDuration:   {10, 0},
    81  	TypeLonglong:   {22, 0},
    82  	TypeDouble:     {22, -1},
    83  	TypeFloat:      {12, -1},
    84  	TypeJSON:       {4194304, 0}, // flen differs.
    85  }
    86  
    87  // GetDefaultFieldLengthAndDecimalForCast returns the default display length (flen) and decimal length for casted column
    88  // when flen or decimal is not specified.
    89  func GetDefaultFieldLengthAndDecimalForCast(tp byte) (flen int, decimal int) {
    90  	val, ok := defaultLengthAndDecimalForCast[tp]
    91  	if ok {
    92  		return val.length, val.decimal
    93  	}
    94  	return -1, -1
    95  }
    96  
    97  // IsAuthPluginClearText is used to indicated that the plugin need clear-text password.
    98  func IsAuthPluginClearText(authPlugin string) bool {
    99  	return authPlugin == AuthNativePassword ||
   100  		authPlugin == AuthTiDBSM3Password ||
   101  		authPlugin == AuthCachingSha2Password
   102  }