Package org.apache.drill.exec.expr.annotations

Annotation Type FunctionTemplate

@Retention(RUNTIME)
@Target(TYPE)
public @interface FunctionTemplate

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static enum	FunctionTemplate.FunctionCostCategory
static enum	FunctionTemplate.FunctionScope	Function scope is used to indicate function output rows relation: simple / scalar (1 -> 1) or aggregate (n -> 1).
static enum	FunctionTemplate.NullHandling
static enum	FunctionTemplate.OutputWidthCalculatorType	Estimates the average size of the output produced by a function that produces variable length output
static enum	FunctionTemplate.ReturnType	Return type enum is used to indicate which return type calculation logic should be used for functions.

Required Element Summary

Required Elements

Modifier and Type	Required Element	Description
FunctionTemplate.FunctionScope	scope

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element	Description
boolean	checkPrecisionRange
FunctionTemplate.FunctionCostCategory	costCategory
String	desc
boolean	isBinaryCommutative
boolean	isInternal	Defines if a function is internal and not intended for public use [e.g.
boolean	isNiladic	Set Operand type-checking strategy for an operator which takes no operands and need to be invoked without parentheses.
boolean	isRandom
boolean	isVarArg	Defines if a function accepts variable arguments count
String	name	Name of function (when only one.) Use this annotation element if there is only one name for the function.
String[]	names	Names of function (when multiple).
FunctionTemplate.NullHandling	nulls
int	outputSizeEstimate
FunctionTemplate.OutputWidthCalculatorType	outputWidthCalculatorType
FunctionTemplate.ReturnType	returnType

Field Summary

Fields

Modifier and Type	Field	Description
static final int	OUTPUT_SIZE_ESTIMATE_DEFAULT

Field Details

OUTPUT_SIZE_ESTIMATE_DEFAULT

static final int OUTPUT_SIZE_ESTIMATE_DEFAULT

See Also:

• Constant Field Values

Element Details

scope

FunctionTemplate.FunctionScope scope

name

String name

Name of function (when only one.) Use this annotation element if there is only one name for the function. Note: If you use this annotation don't use names().

TODO: Refer to wherever list of possible or at least known names is, to resolve the current issue of spaces vs. underlines in names (e.g., we have both "less_than" and "less than".

Returns:

function name

Default:

""

names

String[] names

Names of function (when multiple). Use this annotation element if there are multiple names for the function. Note: If you use this annotation don't use name().

TODO: Refer to wherever list of possible or at least known names is, to resolve the current issue of spaces vs. underlines in names (e.g., we have both "less_than" and "less than".

Returns:

list of function names

Default:

{}

returnType

FunctionTemplate.ReturnType returnType

Default:

DEFAULT

nulls

FunctionTemplate.NullHandling nulls

Default:

INTERNAL

isBinaryCommutative

boolean isBinaryCommutative

Default:

false

isRandom

boolean isRandom

Default:

false

desc

String desc

Default:

""

costCategory

FunctionTemplate.FunctionCostCategory costCategory

Default:

SIMPLE

isNiladic

boolean isNiladic

Set Operand type-checking strategy for an operator which takes no operands and need to be invoked without parentheses. E.g.: session_id is a niladic function.

Niladic functions override columns that have names same as any niladic function. Such columns cannot be queried without the table qualification. Value of the niladic function is returned when table qualification is not used.

For e.g. in the case of session_id:
select session_id from table -> returns the value of niladic function session_id
select t1.session_id from table t1 -> returns session_id column value from table

Default:

false

checkPrecisionRange

boolean checkPrecisionRange

Default:

false

isInternal

boolean isInternal

Defines if a function is internal and not intended for public use [e.g. castEmptyStringNullableVarBinaryToNullableVarDecimal(..) ]

Default:

false

isVarArg

boolean isVarArg

Defines if a function accepts variable arguments count

Default:

false

outputWidthCalculatorType

FunctionTemplate.OutputWidthCalculatorType outputWidthCalculatorType

Default:

DEFAULT

outputSizeEstimate

int outputSizeEstimate

Default:

-1