Documentation
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Index ¶
- func IsAllFirstRow(aggFuncs []*AggFuncDesc) bool
- func NeedFrame(name string) bool
- type AggFuncDesc
- func (a *AggFuncDesc) Clone() *AggFuncDesc
- func (a *AggFuncDesc) Equal(ctx sessionctx.Context, other *AggFuncDesc) bool
- func (a *AggFuncDesc) EvalNullValueInOuterJoin(ctx sessionctx.Context, schema *expression.Schema) (types.Datum, bool)
- func (a *AggFuncDesc) GetDefaultValue() (v types.Datum)
- func (a *AggFuncDesc) String() string
- func (a *AggFuncDesc) WrapCastForAggArgs(ctx sessionctx.Context)
- type AggFunctionMode
- type WindowFuncDesc
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func IsAllFirstRow ¶
func IsAllFirstRow(aggFuncs []*AggFuncDesc) bool
IsAllFirstRow checks whether functions in `aggFuncs` are all FirstRow.
Types ¶
type AggFuncDesc ¶
type AggFuncDesc struct {
// Mode represents the execution mode of the aggregation function.
Mode AggFunctionMode
// HasDistinct represents whether the aggregation function contains distinct attribute.
HasDistinct bool
// UseAsThreshold represents whether the aggregation function(count) uses as a threshold
UseAsThreshold bool
// contains filtered or unexported fields
}
AggFuncDesc describes an aggregation function signature, only used in planner.
func NewAggFuncDesc ¶
func NewAggFuncDesc(ctx sessionctx.Context, name string, args []expression.Expression, hasDistinct bool) (*AggFuncDesc, error)
NewAggFuncDesc creates an aggregation function signature descriptor.
func (*AggFuncDesc) Clone ¶
func (a *AggFuncDesc) Clone() *AggFuncDesc
Clone copies an aggregation function signature totally.
func (*AggFuncDesc) Equal ¶
func (a *AggFuncDesc) Equal(ctx sessionctx.Context, other *AggFuncDesc) bool
Equal checks whether two aggregation function signatures are equal.
func (*AggFuncDesc) EvalNullValueInOuterJoin ¶
func (a *AggFuncDesc) EvalNullValueInOuterJoin(ctx sessionctx.Context, schema *expression.Schema) (types.Datum, bool)
EvalNullValueInOuterJoin gets the null value when the aggregation is upon an outer join, and the aggregation function's input is null. If there is no matching row for the inner table of an outer join, an aggregation function only involves constant and/or columns belongs to the inner table will be set to the null value. The input stands for the schema of Aggregation's child. If the function can't produce a null value, the second return value will be false. e.g. Table t with only one row: +-------+---------+---------+ | Table | Field | Type | +-------+---------+---------+ | t | a | int(11) | +-------+---------+---------+ +------+ | a | +------+ | 1 | +------+
Table s which is empty: +-------+---------+---------+ | Table | Field | Type | +-------+---------+---------+ | s | a | int(11) | +-------+---------+---------+
Query: `select t.a as `t.a`, count(95), sum(95), avg(95), bit_or(95), bit_and(95), bit_or(95), max(95), min(95), s.a as `s.a`, avg(95) from t left join s on t.a = s.a;` +------+-----------+---------+---------+------------+-------------+------------+---------+---------+------+----------+ | t.a | count(95) | sum(95) | avg(95) | bit_or(95) | bit_and(95) | bit_or(95) | max(95) | min(95) | s.a | avg(s.a) | +------+-----------+---------+---------+------------+-------------+------------+---------+---------+------+----------+ | 1 | 1 | 95 | 95.0000 | 95 | 95 | 95 | 95 | 95 | NULL | NULL | +------+-----------+---------+---------+------------+-------------+------------+---------+---------+------+----------+
func (*AggFuncDesc) GetDefaultValue ¶
GetDefaultValue gets the default value when the function's input is null. According to MySQL, default values of the function are listed as follows: e.g. Table t which is empty: +-------+---------+---------+ | Table | Field | Type | +-------+---------+---------+ | t | a | int(11) | +-------+---------+---------+
Query: `select a, avg(a), sum(a), count(a), bit_xor(a), bit_or(a), bit_and(a), max(a), min(a), group_concat(a) from t;` +------+--------+--------+----------+------------+-----------+----------------------+--------+--------+-----------------+ | a | avg(a) | sum(a) | count(a) | bit_xor(a) | bit_or(a) | bit_and(a) | max(a) | min(a) | group_concat(a) | +------+--------+--------+----------+------------+-----------+----------------------+--------+--------+-----------------+ | NULL | NULL | NULL | 0 | 0 | 0 | 18446744073709551615 | NULL | NULL | NULL | +------+--------+--------+----------+------------+-----------+----------------------+--------+--------+-----------------+
func (*AggFuncDesc) String ¶
func (a *AggFuncDesc) String() string
String implements the fmt.Stringer interface.
func (*AggFuncDesc) WrapCastForAggArgs ¶
func (a *AggFuncDesc) WrapCastForAggArgs(ctx sessionctx.Context)
WrapCastForAggArgs wraps the args of an aggregate function with a cast function.
type AggFunctionMode ¶
type AggFunctionMode int
AggFunctionMode stands for the aggregation function's mode.
const ( CompleteMode AggFunctionMode = iota FinalMode Partial1Mode Partial2Mode DedupMode )
|-----------------|--------------|--------------| | AggFunctionMode | input | output | |-----------------|--------------|--------------| | CompleteMode | origin data | final result | | FinalMode | partial data | final result | | Partial1Mode | origin data | partial data | | Partial2Mode | partial data | partial data | | DedupMode | origin data | origin data | |-----------------|--------------|--------------|
type WindowFuncDesc ¶
type WindowFuncDesc struct {
// contains filtered or unexported fields
}
WindowFuncDesc describes a window function signature, only used in planner.
func NewWindowFuncDesc ¶
func NewWindowFuncDesc(ctx sessionctx.Context, name string, args []expression.Expression) (*WindowFuncDesc, error)
NewWindowFuncDesc creates a window function signature descriptor.
func (*WindowFuncDesc) GetDefaultValue ¶
GetDefaultValue gets the default value when the function's input is null. According to MySQL, default values of the function are listed as follows: e.g. Table t which is empty: +-------+---------+---------+ | Table | Field | Type | +-------+---------+---------+ | t | a | int(11) | +-------+---------+---------+
Query: `select a, avg(a), sum(a), count(a), bit_xor(a), bit_or(a), bit_and(a), max(a), min(a), group_concat(a) from t;` +------+--------+--------+----------+------------+-----------+----------------------+--------+--------+-----------------+ | a | avg(a) | sum(a) | count(a) | bit_xor(a) | bit_or(a) | bit_and(a) | max(a) | min(a) | group_concat(a) | +------+--------+--------+----------+------------+-----------+----------------------+--------+--------+-----------------+ | NULL | NULL | NULL | 0 | 0 | 0 | 18446744073709551615 | NULL | NULL | NULL | +------+--------+--------+----------+------------+-----------+----------------------+--------+--------+-----------------+
func (*WindowFuncDesc) String ¶
func (a *WindowFuncDesc) String() string
String implements the fmt.Stringer interface.
func (*WindowFuncDesc) WrapCastForAggArgs ¶
func (a *WindowFuncDesc) WrapCastForAggArgs(ctx sessionctx.Context)
WrapCastForAggArgs wraps the args of an aggregate function with a cast function.
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