org.apache.drill.exec.record.metadata

Interface TupleMetadata

All Superinterfaces:

Iterable<ColumnMetadata>, Propertied

All Known Implementing Classes:

TupleSchema

public interface TupleMetadata
extends Propertied, Iterable<ColumnMetadata>

Metadata description of the schema of a row or a map. In Drill, both rows and maps are tuples: both are an ordered collection of values, defined by a schema. Each tuple has a schema that defines the column ordering for indexed access. Each tuple also provides methods to get column accessors by name or index.

Models the physical schema of a row set showing the logical hierarchy of fields with map fields as first-class fields. Map members appear as children under the map, much as they appear in the physical value-vector implementation.

• Provides fast lookup by name or index.
• Provides a nested schema, in this same form, for maps.

This form is useful when performing semantic analysis and when working with vectors.

In the future, this structure will also gather metadata useful for vector processing such as expected widths and so on.

Field Summary

Fields

Modifier and Type	Field and Description
static String	IS_STRICT_SCHEMA_PROP
static com.fasterxml.jackson.databind.ObjectReader	READER
static com.fasterxml.jackson.databind.ObjectWriter	WRITER

Fields inherited from interface org.apache.drill.exec.record.metadata.Propertied

DRILL_PROP_PREFIX

Method Summary

Modifier and Type	Method and Description
ColumnMetadata	add(MaterializedField field) Add a new column to the schema.
int	addColumn(ColumnMetadata column)
MaterializedField	column(int index)
MaterializedField	column(String name)
TupleMetadata	copy()
String	fullName(ColumnMetadata column) Full name of the column.
String	fullName(int index)
int	index(String name)
boolean	isEmpty()
boolean	isEquivalent(TupleMetadata other)
default String	jsonString() Converts current TupleMetadata implementation into JSON string representation.
ColumnMetadata	metadata(int index)
ColumnMetadata	metadata(String name)
static TupleMetadata	of(String jsonString) Converts given JSON string into TupleMetadata instance.
ColumnMetadata	parent()
void	replace(ColumnMetadata replaceWith)
int	size()
List<MaterializedField>	toFieldList() Return the schema as a list of MaterializedField objects which can be used to create other schemas.
List<ColumnMetadata>	toMetadataList() Returns schema as list of ColumnMetadata objects which can be used to create JSON schema object.

Methods inherited from interface org.apache.drill.exec.record.metadata.Propertied

booleanProperty, booleanProperty, hasProperties, intProperty, intProperty, pluginPrefix, properties, property, property, removeProperty, setBooleanProperty, setIntProperty, setProperties, setProperty

Methods inherited from interface java.lang.Iterable

forEach, iterator, spliterator

Field Detail

WRITER

static final com.fasterxml.jackson.databind.ObjectWriter WRITER

READER

static final com.fasterxml.jackson.databind.ObjectReader READER

IS_STRICT_SCHEMA_PROP

static final String IS_STRICT_SCHEMA_PROP

See Also:

Constant Field Values

Method Detail

add

ColumnMetadata add(MaterializedField field)

Add a new column to the schema.

Parameters:

field - materialized field

Returns:

the index of the new column

addColumn

int addColumn(ColumnMetadata column)

size

int size()

isEmpty

boolean isEmpty()

index

int index(String name)

metadata

ColumnMetadata metadata(int index)

metadata

ColumnMetadata metadata(String name)

column

MaterializedField column(int index)

column

MaterializedField column(String name)

isEquivalent

boolean isEquivalent(TupleMetadata other)

parent

ColumnMetadata parent()

toFieldList

List<MaterializedField> toFieldList()

Return the schema as a list of MaterializedField objects which can be used to create other schemas. Not valid for a flattened schema.

Returns:

a list of the top-level fields. Maps contain their child fields

toMetadataList

List<ColumnMetadata> toMetadataList()

Returns schema as list of ColumnMetadata objects which can be used to create JSON schema object.

Returns:

a list of metadata for each column

fullName

String fullName(ColumnMetadata column)

Full name of the column. Note: this name cannot be used to look up the column because of ambiguity. The name "a.b.c" may mean a single column with that name, or may mean maps "a", and "b" with column "c", etc.

Returns:

full, dotted, column name

fullName

String fullName(int index)

copy

TupleMetadata copy()

replace

void replace(ColumnMetadata replaceWith)

jsonString

default String jsonString()

Converts current TupleMetadata implementation into JSON string representation.

Returns:

tuple metadata in JSON string representation

Throws:

IllegalStateException - if unable to convert current instance into JSON string

of

static TupleMetadata of(String jsonString)

Converts given JSON string into TupleMetadata instance. TupleMetadata implementation is determined by present type property. For example: "type":"tuple_schema". If given JSON string is untyped, used default implementation: TupleSchema.

Parameters:

jsonString - tuple metadata in JSON string representation

Returns:

TupleMetadata instance, null if given JSON string is null or empty

Throws:

IllegalArgumentException - if unable to deserialize given JSON string