expression

package
v1.0.3 Latest Latest
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 Go to latest Published: Nov 25, 2017 License: Apache-2.0 Imports: 49 Imported by: 0

Documentation

Index

Constants

View Source 
const (
	SHA0   int = 0
	SHA224 int = 224
	SHA256 int = 256
	SHA384 int = 384
	SHA512 int = 512
)

Supported hash length of SHA-2 family

Variables

View Source 
var (
	// One stands for a number 1.
	One = &Constant{
		Value:   types.NewDatum(1),
		RetType: types.NewFieldType(mysql.TypeTiny),
	}

	// Zero stands for a number 0.
	Zero = &Constant{
		Value:   types.NewDatum(0),
		RetType: types.NewFieldType(mysql.TypeTiny),
	}

	// Null stands for null constant.
	Null = &Constant{
		Value:   types.NewDatum(nil),
		RetType: types.NewFieldType(mysql.TypeTiny),
	}
)
View Source 
var (
	ErrIncorrectParameterCount = terror.ClassExpression.New(mysql.ErrWrongParamcountToNativeFct, mysql.MySQLErrName[mysql.ErrWrongParamcountToNativeFct])
	ErrDivisionByZero          = terror.ClassExpression.New(mysql.ErrDivisionByZero, mysql.MySQLErrName[mysql.ErrDivisionByZero])
)

Error instances.

View Source 
var EvalAstExpr func(expr ast.ExprNode, ctx context.Context) (types.Datum, error)

EvalAstExpr evaluates ast expression directly.

View Source 
var MaxPropagateColsCnt = 100

MaxPropagateColsCnt means the max number of columns that can participate propagation.

View Source 
var UnCacheableFunctions = map[string]struct{}{
	ast.Now:              {},
	ast.CurrentTimestamp: {},
	ast.UTCTime:          {},
	ast.Curtime:          {},
	ast.CurrentTime:      {},
	ast.UTCTimestamp:     {},
	ast.UnixTimestamp:    {},
	ast.Sysdate:          {},
	ast.Curdate:          {},
	ast.CurrentDate:      {},
	ast.UTCDate:          {},
	ast.Database:         {},
	ast.CurrentUser:      {},
	ast.User:             {},
	ast.ConnectionID:     {},
	ast.LastInsertId:     {},
	ast.Version:          {},
}

UnCacheableFunctions stores functions which can not be cached to plan cache.

Functions

func EvalBool 

func EvalBool(exprList CNFExprs, row []types.Datum, ctx context.Context) (bool, error)

EvalBool evaluates expression list to a boolean value.

func ExplainColumnList 

func ExplainColumnList(cols []*Column) []byte

ExplainColumnList generates explain information for a list of columns.

func ExplainExpressionList 

func ExplainExpressionList(exprs []Expression) []byte

ExplainExpressionList generates explain information for a list of expressions.

func ExprFromSchema 

func ExprFromSchema(expr Expression, schema *Schema) bool

ExprFromSchema checks if all columns of this expression are from the same schema.

func ExpressionsToPB 

func ExpressionsToPB(sc *variable.StatementContext, exprs []Expression, client kv.Client) (pbExpr *tipb.Expr, pushed []Expression, remained []Expression)

ExpressionsToPB converts expression to tipb.Expr.

func ExpressionsToPBList 

func ExpressionsToPBList(sc *variable.StatementContext, exprs []Expression, client kv.Client) (pbExpr []*tipb.Expr)

ExpressionsToPBList converts expressions to tipb.Expr list for new plan.

func GetAccurateCmpType 

func GetAccurateCmpType(lhs, rhs Expression) types.EvalType

GetAccurateCmpType uses a more complex logic to decide the EvalType of the two args when compare with each other than getBaseCmpType does.

func GetTimeValue 

func GetTimeValue(ctx context.Context, v interface{}, tp byte, fsp int) (d types.Datum, err error)

GetTimeValue gets the time value with type tp.

func GroupByItemToPB 

func GroupByItemToPB(sc *variable.StatementContext, client kv.Client, expr Expression) *tipb.ByItem

GroupByItemToPB converts group by items to pb.

func IsCurrentTimestampExpr 

func IsCurrentTimestampExpr(e ast.ExprNode) bool

IsCurrentTimestampExpr returns whether e is CurrentTimestamp expression.

func IsHybridType 

func IsHybridType(expr Expression) bool

IsHybridType checks whether a ClassString expression is a hybrid type value which will return different types of value in different context.

For ENUM/SET which is consist of a string attribute `Name` and an int attribute `Value`, it will cause an error if we convert ENUM/SET to int as a string value.

For BinaryLiteral/MysqlBit, we will get a wrong result if we convert it to int as a string value. For example, when convert `0b101` to int, the result should be 5, but we will get 101 if we regard it as a string.

func SetBinFlagOrBinStr 

func SetBinFlagOrBinStr(argTp *types.FieldType, resTp *types.FieldType)

SetBinFlagOrBinStr sets resTp to binary string if argTp is a binary string, if not, sets the binary flag of resTp to true if argTp has binary flag.

func SortByItemToPB 

func SortByItemToPB(sc *variable.StatementContext, client kv.Client, expr Expression, desc bool) *tipb.ByItem

SortByItemToPB converts order by items to pb.

Types

type Assignment 

type Assignment struct {
	Col  *Column
	Expr Expression
}

Assignment represents a set assignment in Update, such as Update t set c1 = hex(12), c2 = c3 where c2 = 1

type CNFExprs 

type CNFExprs []Expression

CNFExprs stands for a CNF expression.

func (CNFExprs) Clone 

func (e CNFExprs) Clone() CNFExprs

Clone clones itself.

type Column 

type Column struct {
	FromID      int
	ColName     model.CIStr
	DBName      model.CIStr
	OrigTblName model.CIStr
	TblName     model.CIStr
	RetType     *types.FieldType
	ID          int64
	// Position means the position of this column that appears in the select fields.
	// e.g. SELECT name as id , 1 - id as id , 1 + name as id, name as id from src having id = 1;
	// There are four ids in the same schema, so you can't identify the column through the FromID and ColName.
	Position int
	// IsAggOrSubq means if this column is referenced to a Aggregation column or a Subquery column.
	// If so, this column's name will be the plain sql text.
	IsAggOrSubq bool

	// Index is only used for execution.
	Index int
	// contains filtered or unexported fields
}

Column represents a column.

func ColInfo2Col 

func ColInfo2Col(cols []*Column, col *model.ColumnInfo) *Column

ColInfo2Col finds the corresponding column of the ColumnInfo in a column slice.

func ColumnInfos2Columns 

func ColumnInfos2Columns(tblName model.CIStr, colInfos []*model.ColumnInfo) []*Column

ColumnInfos2Columns converts a slice of ColumnInfo to a slice of Column with empty DBName.

func ColumnInfos2ColumnsWithDBName 

func ColumnInfos2ColumnsWithDBName(dbName, tblName model.CIStr, colInfos []*model.ColumnInfo) []*Column

ColumnInfos2ColumnsWithDBName converts a slice of ColumnInfo to a slice of Column.

func ExtractColumns 

func ExtractColumns(expr Expression) (cols []*Column)

ExtractColumns extracts all columns from an expression.

func IndexInfo2Cols 

func IndexInfo2Cols(cols []*Column, index *model.IndexInfo) ([]*Column, []int)

IndexInfo2Cols gets the corresponding []*Column of the indexInfo's []*IndexColumn, together with a []int containing their lengths. If this index has three IndexColumn that the 1st and 3rd IndexColumn has corresponding *Column, the return value will be only the 1st corresponding *Column and its length.

func (*Column) Clone 

func (col *Column) Clone() Expression

Clone implements Expression interface.

func (*Column) Decorrelate 

func (col *Column) Decorrelate(_ *Schema) Expression

Decorrelate implements Expression interface.

func (*Column) Equal 

func (col *Column) Equal(expr Expression, _ context.Context) bool

Equal implements Expression interface.

func (*Column) Eval 

func (col *Column) Eval(row []types.Datum) (types.Datum, error)

Eval implements Expression interface.

func (*Column) EvalDecimal 

func (col *Column) EvalDecimal(row []types.Datum, sc *variable.StatementContext) (*types.MyDecimal, bool, error)

EvalDecimal returns decimal representation of Column.

func (*Column) EvalDuration 

func (col *Column) EvalDuration(row []types.Datum, sc *variable.StatementContext) (types.Duration, bool, error)

EvalDuration returns Duration representation of Column.

func (*Column) EvalInt 

func (col *Column) EvalInt(row []types.Datum, sc *variable.StatementContext) (int64, bool, error)

EvalInt returns int representation of Column.

func (*Column) EvalJSON 

func (col *Column) EvalJSON(row []types.Datum, sc *variable.StatementContext) (json.JSON, bool, error)

EvalJSON returns JSON representation of Column.

func (*Column) EvalReal 

func (col *Column) EvalReal(row []types.Datum, sc *variable.StatementContext) (float64, bool, error)

EvalReal returns real representation of Column.

func (*Column) EvalString 

func (col *Column) EvalString(row []types.Datum, sc *variable.StatementContext) (string, bool, error)

EvalString returns string representation of Column.

func (*Column) EvalTime 

func (col *Column) EvalTime(row []types.Datum, sc *variable.StatementContext) (types.Time, bool, error)

EvalTime returns DATE/DATETIME/TIMESTAMP representation of Column.

func (*Column) ExplainInfo 

func (expr *Column) ExplainInfo() string

ExplainInfo implements the Expression interface.

func (*Column) GetType 

func (col *Column) GetType() *types.FieldType

GetType implements Expression interface.

func (*Column) HashCode 

func (col *Column) HashCode() []byte

HashCode implements Expression interface.

func (*Column) IsCorrelated 

func (col *Column) IsCorrelated() bool

IsCorrelated implements Expression interface.

func (*Column) MarshalJSON 

func (col *Column) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler interface.

func (*Column) ResolveIndices 

func (col *Column) ResolveIndices(schema *Schema)

ResolveIndices implements Expression interface.

func (*Column) String 

func (col *Column) String() string

String implements Stringer interface.

type Constant 

type Constant struct {
	Value   types.Datum
	RetType *types.FieldType
}

Constant stands for a constant value.

func RefineConstantArg 

func RefineConstantArg(ctx context.Context, con *Constant, op opcode.Op) *Constant

RefineConstantArg changes the constant argument to it's ceiling or flooring result by the given op.

func (*Constant) Clone 

func (c *Constant) Clone() Expression

Clone implements Expression interface.

func (*Constant) Decorrelate 

func (c *Constant) Decorrelate(_ *Schema) Expression

Decorrelate implements Expression interface.

func (*Constant) Equal 

func (c *Constant) Equal(b Expression, ctx context.Context) bool

Equal implements Expression interface.

func (*Constant) Eval 

func (c *Constant) Eval(_ []types.Datum) (types.Datum, error)

Eval implements Expression interface.

func (*Constant) EvalDecimal 

func (c *Constant) EvalDecimal(_ []types.Datum, sc *variable.StatementContext) (*types.MyDecimal, bool, error)

EvalDecimal returns decimal representation of Constant.

func (*Constant) EvalDuration 

func (c *Constant) EvalDuration(_ []types.Datum, sc *variable.StatementContext) (val types.Duration, isNull bool, err error)

EvalDuration returns Duration representation of Constant.

func (*Constant) EvalInt 

func (c *Constant) EvalInt(_ []types.Datum, sc *variable.StatementContext) (int64, bool, error)

EvalInt returns int representation of Constant.

func (*Constant) EvalJSON 

func (c *Constant) EvalJSON(_ []types.Datum, sc *variable.StatementContext) (json.JSON, bool, error)

EvalJSON returns JSON representation of Constant.

func (*Constant) EvalReal 

func (c *Constant) EvalReal(_ []types.Datum, sc *variable.StatementContext) (float64, bool, error)

EvalReal returns real representation of Constant.

func (*Constant) EvalString 

func (c *Constant) EvalString(_ []types.Datum, sc *variable.StatementContext) (string, bool, error)

EvalString returns string representation of Constant.

func (*Constant) EvalTime 

func (c *Constant) EvalTime(_ []types.Datum, sc *variable.StatementContext) (val types.Time, isNull bool, err error)

EvalTime returns DATE/DATETIME/TIMESTAMP representation of Constant.

func (*Constant) ExplainInfo 

func (expr *Constant) ExplainInfo() string

ExplainInfo implements the Expression interface.

func (*Constant) GetType 

func (c *Constant) GetType() *types.FieldType

GetType implements Expression interface.

func (*Constant) HashCode 

func (c *Constant) HashCode() []byte

HashCode implements Expression interface.

func (*Constant) IsCorrelated 

func (c *Constant) IsCorrelated() bool

IsCorrelated implements Expression interface.

func (*Constant) MarshalJSON 

func (c *Constant) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler interface.

func (*Constant) ResolveIndices 

func (c *Constant) ResolveIndices(_ *Schema)

ResolveIndices implements Expression interface.

func (*Constant) String 

func (c *Constant) String() string

String implements fmt.Stringer interface.

type CorrelatedColumn 

type CorrelatedColumn struct {
	Column

	Data *types.Datum
}

CorrelatedColumn stands for a column in a correlated sub query.

func (*CorrelatedColumn) Clone 

func (col *CorrelatedColumn) Clone() Expression

Clone implements Expression interface.

func (*CorrelatedColumn) Decorrelate 

func (col *CorrelatedColumn) Decorrelate(schema *Schema) Expression

Decorrelate implements Expression interface.

func (*CorrelatedColumn) Equal 

func (col *CorrelatedColumn) Equal(expr Expression, ctx context.Context) bool

Equal implements Expression interface.

func (*CorrelatedColumn) Eval 

func (col *CorrelatedColumn) Eval(row []types.Datum) (types.Datum, error)

Eval implements Expression interface.

func (*CorrelatedColumn) EvalDecimal 

func (col *CorrelatedColumn) EvalDecimal(row []types.Datum, sc *variable.StatementContext) (*types.MyDecimal, bool, error)

EvalDecimal returns decimal representation of CorrelatedColumn.

func (*CorrelatedColumn) EvalDuration 

func (col *CorrelatedColumn) EvalDuration(row []types.Datum, sc *variable.StatementContext) (types.Duration, bool, error)

EvalDuration returns Duration representation of CorrelatedColumn.

func (*CorrelatedColumn) EvalInt 

func (col *CorrelatedColumn) EvalInt(row []types.Datum, sc *variable.StatementContext) (int64, bool, error)

EvalInt returns int representation of CorrelatedColumn.

func (*CorrelatedColumn) EvalJSON 

func (col *CorrelatedColumn) EvalJSON(row []types.Datum, sc *variable.StatementContext) (json.JSON, bool, error)

EvalJSON returns JSON representation of CorrelatedColumn.

func (*CorrelatedColumn) EvalReal 

func (col *CorrelatedColumn) EvalReal(row []types.Datum, sc *variable.StatementContext) (float64, bool, error)

EvalReal returns real representation of CorrelatedColumn.

func (*CorrelatedColumn) EvalString 

func (col *CorrelatedColumn) EvalString(row []types.Datum, sc *variable.StatementContext) (string, bool, error)

EvalString returns string representation of CorrelatedColumn.

func (*CorrelatedColumn) EvalTime 

func (col *CorrelatedColumn) EvalTime(row []types.Datum, sc *variable.StatementContext) (types.Time, bool, error)

EvalTime returns DATE/DATETIME/TIMESTAMP representation of CorrelatedColumn.

func (*CorrelatedColumn) IsCorrelated 

func (col *CorrelatedColumn) IsCorrelated() bool

IsCorrelated implements Expression interface.

func (*CorrelatedColumn) ResolveIndices 

func (col *CorrelatedColumn) ResolveIndices(_ *Schema)

ResolveIndices implements Expression interface.

type Expression 

type Expression interface {
	fmt.Stringer
	goJSON.Marshaler

	// Eval evaluates an expression through a row.
	Eval(row []types.Datum) (types.Datum, error)

	// EvalInt returns the int64 representation of expression.
	EvalInt(row []types.Datum, sc *variable.StatementContext) (val int64, isNull bool, err error)

	// EvalReal returns the float64 representation of expression.
	EvalReal(row []types.Datum, sc *variable.StatementContext) (val float64, isNull bool, err error)

	// EvalString returns the string representation of expression.
	EvalString(row []types.Datum, sc *variable.StatementContext) (val string, isNull bool, err error)

	// EvalDecimal returns the decimal representation of expression.
	EvalDecimal(row []types.Datum, sc *variable.StatementContext) (val *types.MyDecimal, isNull bool, err error)

	// EvalTime returns the DATE/DATETIME/TIMESTAMP representation of expression.
	EvalTime(row []types.Datum, sc *variable.StatementContext) (val types.Time, isNull bool, err error)

	// EvalDuration returns the duration representation of expression.
	EvalDuration(row []types.Datum, sc *variable.StatementContext) (val types.Duration, isNull bool, err error)

	// EvalJSON returns the JSON representation of expression.
	EvalJSON(row []types.Datum, sc *variable.StatementContext) (val json.JSON, isNull bool, err error)

	// GetType gets the type that the expression returns.
	GetType() *types.FieldType

	// Clone copies an expression totally.
	Clone() Expression

	// HashCode create the hashcode for expression
	HashCode() []byte

	// Equal checks whether two expressions are equal.
	Equal(e Expression, ctx context.Context) bool

	// IsCorrelated checks if this expression has correlated key.
	IsCorrelated() bool

	// Decorrelate try to decorrelate the expression by schema.
	Decorrelate(schema *Schema) Expression

	// ResolveIndices resolves indices by the given schema.
	ResolveIndices(schema *Schema)

	// ExplainInfo returns operator information to be explained.
	ExplainInfo() string
}

Expression represents all scalar expression in SQL.

func BuildCastFunction 

func BuildCastFunction(ctx context.Context, expr Expression, tp *types.FieldType) (res Expression)

BuildCastFunction builds a CAST ScalarFunction from the Expression.

func Column2Exprs 

func Column2Exprs(cols []*Column) []Expression

Column2Exprs will transfer column slice to expression slice.

func ColumnSubstitute 

func ColumnSubstitute(expr Expression, schema *Schema, newExprs []Expression) Expression

ColumnSubstitute substitutes the columns in filter to expressions in select fields. e.g. select * from (select b as a from t) k where a < 10 => select * from (select b as a from t where b < 10) k.

func ComposeCNFCondition 

func ComposeCNFCondition(ctx context.Context, conditions ...Expression) Expression

ComposeCNFCondition composes CNF items into a balance deep CNF tree, which benefits a lot for pb decoder/encoder.

func ComposeDNFCondition 

func ComposeDNFCondition(ctx context.Context, conditions ...Expression) Expression

ComposeDNFCondition composes DNF items into a balance deep DNF tree.

func ConvertCol2CorCol 

func ConvertCol2CorCol(cond Expression, corCols []*CorrelatedColumn, outerSchema *Schema) Expression

ConvertCol2CorCol will convert the column in the condition which can be found in outerSchema to a correlated column whose Column is this column. And please make sure the outerSchema.Columns[i].Equal(corCols[i].Column)) holds when you call this.

func EvaluateExprWithNull 

func EvaluateExprWithNull(ctx context.Context, schema *Schema, expr Expression) (Expression, error)

EvaluateExprWithNull sets columns in schema as null and calculate the final result of the scalar function. If the Expression is a non-constant value, it means the result is unknown.

func FoldConstant 

func FoldConstant(expr Expression) Expression

FoldConstant does constant folding optimization on an expression.

func NewFunction 

func NewFunction(ctx context.Context, funcName string, retType *types.FieldType, args ...Expression) (Expression, error)

NewFunction creates a new scalar function or constant.

func NewFunctionInternal 

func NewFunctionInternal(ctx context.Context, funcName string, retType *types.FieldType, args ...Expression) Expression

NewFunctionInternal is similar to NewFunction, but do not returns error, should only be used internally.

func PBToExpr 

func PBToExpr(expr *tipb.Expr, tps []*types.FieldType, sc *variable.StatementContext) (Expression, error)

PBToExpr converts pb structure to expression.

func PropagateConstant 

func PropagateConstant(ctx context.Context, conditions []Expression) []Expression

PropagateConstant propagate constant values of equality predicates and inequality predicates in a condition.

func PushDownNot 

func PushDownNot(expr Expression, not bool, ctx context.Context) Expression

PushDownNot pushes the `not` function down to the expression's arguments.

func ScalarFuncs2Exprs 

func ScalarFuncs2Exprs(funcs []*ScalarFunction) []Expression

ScalarFuncs2Exprs converts []*ScalarFunction to []Expression.

func SplitCNFItems 

func SplitCNFItems(onExpr Expression) []Expression

SplitCNFItems splits CNF items. CNF means conjunctive normal form, e.g. "a and b and c".

func SplitDNFItems 

func SplitDNFItems(onExpr Expression) []Expression

SplitDNFItems splits DNF items. DNF means disjunctive normal form, e.g. "a or b or c".

func SubstituteCorCol2Constant 

func SubstituteCorCol2Constant(expr Expression) (Expression, error)

SubstituteCorCol2Constant will substitute correlated column to constant value which it contains. If the args of one scalar function are all constant, we will substitute it to constant.

func WrapWithCastAsDecimal 

func WrapWithCastAsDecimal(ctx context.Context, expr Expression) Expression

WrapWithCastAsDecimal wraps `expr` with `cast` if the return type of expr is not type decimal, otherwise, returns `expr` directly.

func WrapWithCastAsDuration 

func WrapWithCastAsDuration(ctx context.Context, expr Expression) Expression

WrapWithCastAsDuration wraps `expr` with `cast` if the return type of expr is not type duration, otherwise, returns `expr` directly.

func WrapWithCastAsInt 

func WrapWithCastAsInt(ctx context.Context, expr Expression) Expression

WrapWithCastAsInt wraps `expr` with `cast` if the return type of expr is not type int, otherwise, returns `expr` directly.

func WrapWithCastAsJSON 

func WrapWithCastAsJSON(ctx context.Context, expr Expression) Expression

WrapWithCastAsJSON wraps `expr` with `cast` if the return type of expr is not type json, otherwise, returns `expr` directly.

func WrapWithCastAsReal 

func WrapWithCastAsReal(ctx context.Context, expr Expression) Expression

WrapWithCastAsReal wraps `expr` with `cast` if the return type of expr is not type real, otherwise, returns `expr` directly.

func WrapWithCastAsString 

func WrapWithCastAsString(ctx context.Context, expr Expression) Expression

WrapWithCastAsString wraps `expr` with `cast` if the return type of expr is not type string, otherwise, returns `expr` directly.

func WrapWithCastAsTime 

func WrapWithCastAsTime(ctx context.Context, expr Expression, tp *types.FieldType) Expression

WrapWithCastAsTime wraps `expr` with `cast` if the return type of expr is not same as type of the specified `tp` , otherwise, returns `expr` directly.

type KeyInfo 

type KeyInfo []*Column

KeyInfo stores the columns of one unique key or primary key.

func (KeyInfo) Clone 

func (ki KeyInfo) Clone() KeyInfo

Clone copies the entire UniqueKey.

type PbConverter 

type PbConverter struct {
	// contains filtered or unexported fields
}

PbConverter supplys methods to convert TiDB expressions to TiPB.

func NewPBConverter 

func NewPBConverter(client kv.Client, sc *variable.StatementContext) PbConverter

NewPBConverter creates a PbConverter.

func (PbConverter) ExprToPB 

func (pc PbConverter) ExprToPB(expr Expression) *tipb.Expr

ExprToPB converts Expression to TiPB.

type ScalarFunction 

type ScalarFunction struct {
	FuncName model.CIStr
	// RetType is the type that ScalarFunction returns.
	// TODO: Implement type inference here, now we use ast's return type temporarily.
	RetType  *types.FieldType
	Function builtinFunc
}

ScalarFunction is the function that returns a value.

func NewValuesFunc 

func NewValuesFunc(offset int, retTp *types.FieldType, ctx context.Context) *ScalarFunction

NewValuesFunc creates a new values function.

func (*ScalarFunction) Clone 

func (sf *ScalarFunction) Clone() Expression

Clone implements Expression interface.

func (*ScalarFunction) Decorrelate 

func (sf *ScalarFunction) Decorrelate(schema *Schema) Expression

Decorrelate implements Expression interface.

func (*ScalarFunction) Equal 

func (sf *ScalarFunction) Equal(e Expression, ctx context.Context) bool

Equal implements Expression interface.

func (*ScalarFunction) Eval 

func (sf *ScalarFunction) Eval(row []types.Datum) (d types.Datum, err error)

Eval implements Expression interface.

func (*ScalarFunction) EvalDecimal 

func (sf *ScalarFunction) EvalDecimal(row []types.Datum, sc *variable.StatementContext) (*types.MyDecimal, bool, error)

EvalDecimal implements Expression interface.

func (*ScalarFunction) EvalDuration 

func (sf *ScalarFunction) EvalDuration(row []types.Datum, sc *variable.StatementContext) (types.Duration, bool, error)

EvalDuration implements Expression interface.

func (*ScalarFunction) EvalInt 

func (sf *ScalarFunction) EvalInt(row []types.Datum, sc *variable.StatementContext) (int64, bool, error)

EvalInt implements Expression interface.

func (*ScalarFunction) EvalJSON 

func (sf *ScalarFunction) EvalJSON(row []types.Datum, sc *variable.StatementContext) (json.JSON, bool, error)

EvalJSON implements Expression interface.

func (*ScalarFunction) EvalReal 

func (sf *ScalarFunction) EvalReal(row []types.Datum, sc *variable.StatementContext) (float64, bool, error)

EvalReal implements Expression interface.

func (*ScalarFunction) EvalString 

func (sf *ScalarFunction) EvalString(row []types.Datum, sc *variable.StatementContext) (string, bool, error)

EvalString implements Expression interface.

func (*ScalarFunction) EvalTime 

func (sf *ScalarFunction) EvalTime(row []types.Datum, sc *variable.StatementContext) (types.Time, bool, error)

EvalTime implements Expression interface.

func (*ScalarFunction) ExplainInfo 

func (expr *ScalarFunction) ExplainInfo() string

ExplainInfo implements the Expression interface.

func (*ScalarFunction) GetArgs 

func (sf *ScalarFunction) GetArgs() []Expression

GetArgs gets arguments of function.

func (*ScalarFunction) GetCtx 

func (sf *ScalarFunction) GetCtx() context.Context

GetCtx gets the context of function.

func (*ScalarFunction) GetType 

func (sf *ScalarFunction) GetType() *types.FieldType

GetType implements Expression interface.

func (*ScalarFunction) HashCode 

func (sf *ScalarFunction) HashCode() []byte

HashCode implements Expression interface.

func (*ScalarFunction) IsCorrelated 

func (sf *ScalarFunction) IsCorrelated() bool

IsCorrelated implements Expression interface.

func (*ScalarFunction) MarshalJSON 

func (sf *ScalarFunction) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler interface.

func (*ScalarFunction) ResolveIndices 

func (sf *ScalarFunction) ResolveIndices(schema *Schema)

ResolveIndices implements Expression interface.

func (*ScalarFunction) String 

func (sf *ScalarFunction) String() string

String implements fmt.Stringer interface.

type Schema 

type Schema struct {
	Columns []*Column
	Keys    []KeyInfo
	// TblID2Handle stores the tables' handle column information if we need handle in execution phase.
	TblID2Handle map[int64][]*Column
	MaxOneRow    bool
}

Schema stands for the row schema and unique key information get from input.

func MergeSchema 

func MergeSchema(lSchema, rSchema *Schema) *Schema

MergeSchema will merge two schema into one schema.

func NewSchema 

func NewSchema(cols ...*Column) *Schema

NewSchema returns a schema made by its parameter.

func TableInfo2Schema 

func TableInfo2Schema(tbl *model.TableInfo) *Schema

TableInfo2Schema converts table info to schema with empty DBName.

func TableInfo2SchemaWithDBName 

func TableInfo2SchemaWithDBName(dbName model.CIStr, tbl *model.TableInfo) *Schema

TableInfo2SchemaWithDBName converts table info to schema.

func (*Schema) Append 

func (s *Schema) Append(col ...*Column)

Append append new column to the columns stored in schema.

func (*Schema) Clone 

func (s *Schema) Clone() *Schema

Clone copies the total schema.

func (*Schema) ColumnIndex 

func (s *Schema) ColumnIndex(col *Column) int

ColumnIndex finds the index for a column.

func (*Schema) ColumnsByIndices 

func (s *Schema) ColumnsByIndices(offsets []int) []*Column

ColumnsByIndices returns columns by multiple offsets. Callers should guarantee that all the offsets provided should be valid, which means offset should: 1. not smaller than 0, and 2. not exceed len(s.Columns)

func (*Schema) ColumnsIndices 

func (s *Schema) ColumnsIndices(cols []*Column) (ret []int)

ColumnsIndices will return a slice which contains the position of each column in schema. If there is one column that doesn't match, nil will be returned.

func (*Schema) Contains 

func (s *Schema) Contains(col *Column) bool

Contains checks if the schema contains the column.

func (*Schema) FindColumn 

func (s *Schema) FindColumn(astCol *ast.ColumnName) (*Column, error)

FindColumn finds an Column from schema for a ast.ColumnName. It compares the db/table/column names. If there are more than one result, it will raise ambiguous error.

func (*Schema) FindColumnAndIndex 

func (s *Schema) FindColumnAndIndex(astCol *ast.ColumnName) (*Column, int, error)

FindColumnAndIndex finds an Column and its index from schema for a ast.ColumnName. It compares the db/table/column names. If there are more than one result, raise ambiguous error.

func (*Schema) IsUniqueKey 

func (s *Schema) IsUniqueKey(col *Column) bool

IsUniqueKey checks if this column is a unique key.

func (*Schema) Len 

func (s *Schema) Len() int

Len returns the number of columns in schema.

func (*Schema) RetrieveColumn 

func (s *Schema) RetrieveColumn(col *Column) *Column

RetrieveColumn retrieves column in expression from the columns in schema.

func (*Schema) SetUniqueKeys 

func (s *Schema) SetUniqueKeys(keys []KeyInfo)

SetUniqueKeys will set the value of Schema.Keys.

func (*Schema) String 

func (s *Schema) String() string

String implements fmt.Stringer interface.

type VarAssignment 

type VarAssignment struct {
	Name        string
	Expr        Expression
	IsDefault   bool
	IsGlobal    bool
	IsSystem    bool
	ExtendValue *Constant
}

VarAssignment represents a variable assignment in Set, such as set global a = 1.

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