org.apache.drill.exec.record.metadata

Class DynamicColumn

java.lang.Object

org.apache.drill.exec.record.metadata.AbstractPropertied

org.apache.drill.exec.record.metadata.AbstractColumnMetadata

org.apache.drill.exec.record.metadata.DynamicColumn

All Implemented Interfaces:

ColumnMetadata, Propertied

Direct Known Subclasses:

ProjectedColumn

public class DynamicColumn
extends AbstractColumnMetadata

A dynamic column has a name but not a type. The column may be a map, array or scalar: we don't yet know. A dynamic column is the equivalent of an item in a name-only project list. This type can also represent a wildcard. A dynamic column is not a concrete data description: it must be resolved to an actual type before it can be used to create vectors, readers, writers, etc. The dynamic column allows the tuple metadata to be used to represent all phases of a schema lifecycle, including Drill's "dynamic" schema before a reader resolves the column to some actual type.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.drill.exec.record.metadata.ColumnMetadata

ColumnMetadata.StructureType

Field Summary

Fields

Modifier and Type	Field and Description
static String	WILDCARD
static DynamicColumn	WILDCARD_COLUMN

Fields inherited from class org.apache.drill.exec.record.metadata.AbstractColumnMetadata

mode, name, precision, scale, type

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

BLANK_AS_NULL, BLANK_AS_PROP, BLANK_AS_ZERO, DEFAULT_ARRAY_SIZE, DEFAULT_VALUE_PROP, EXCLUDE_FROM_WILDCARD, EXPECTED_CARDINALITY_PROP, EXPECTED_WIDTH_PROP, FORMAT_PROP, IMPLICIT_COL_TYPE, IMPLICIT_FILENAME, IMPLICIT_FILEPATH, IMPLICIT_FQN, IMPLICIT_PARTITION_PREFIX, IMPLICIT_SUFFIX

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

DRILL_PROP_PREFIX

Constructor Summary

Constructors

Constructor and Description
DynamicColumn(String name)

Method Summary

Modifier and Type	Method and Description
ColumnMetadata	cloneEmpty() Create an empty version of this column.
String	columnString() Converts column metadata into string representation accepted by the table schema parser.
ColumnMetadata	copy()
MaterializedField	emptySchema()
boolean	isDynamic() Reports if the column is dynamic.
boolean	isEquivalent(ColumnMetadata o) Report whether one column is equivalent to another.
MaterializedField	schema()
ColumnMetadata.StructureType	structureType()
String	typeString() Converts type metadata into string representation accepted by the table schema parser.

Methods inherited from class org.apache.drill.exec.record.metadata.AbstractColumnMetadata

appendContents, bind, childSchema, createColumnMetadata, dateTimeFormatter, decodeDefaultValue, defaultValue, dimensions, equals, equalsWithProperties, equalsWithProperties, escapeSpecialSymbols, expectedElementCount, expectedWidth, format, isArray, isDict, isMap, isMultiList, isNullable, isVariableWidth, isVariant, majorType, mode, name, precision, properties, scale, setDefaultValue, setExpectedElementCount, setExpectedWidth, setFormat, toString, tupleSchema, type, valueFromString, valueToString, variantSchema

Methods inherited from class org.apache.drill.exec.record.metadata.AbstractPropertied

booleanProperty, booleanProperty, hashCode, hasProperties, intProperty, intProperty, property, property, removeProperty, setBooleanProperty, setIntProperty, setProperties, setProperty

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

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

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

Field Detail

WILDCARD

public static final String WILDCARD

See Also:

Constant Field Values

WILDCARD_COLUMN

public static final DynamicColumn WILDCARD_COLUMN

Constructor Detail

DynamicColumn

public DynamicColumn(String name)

Method Detail

structureType

public ColumnMetadata.StructureType structureType()

isDynamic

public boolean isDynamic()

Description copied from interface: ColumnMetadata

Reports if the column is dynamic. A dynamic column is one with a "type to be named later." It is valid for describing a dynamic schema, but not for creating vectors; to create a vector the column must be resolved to a concrete type. The context should make it clear if any columns can be dynamic.

Specified by:

isDynamic in interface ColumnMetadata

Overrides:

isDynamic in class AbstractColumnMetadata

Returns:

true if the column does not yet have a concrete type, false if the column type is concrete

schema

public MaterializedField schema()

emptySchema

public MaterializedField emptySchema()

cloneEmpty

public ColumnMetadata cloneEmpty()

Description copied from interface: ColumnMetadata

Create an empty version of this column. If the column is a scalar, produces a simple copy. If a map, produces a clone without child columns.

Returns:

empty clone of this column

copy

public ColumnMetadata copy()

isEquivalent

public boolean isEquivalent(ColumnMetadata o)

Description copied from interface: ColumnMetadata

Report whether one column is equivalent to another. Columns are equivalent if they have the same name, type and structure (ignoring internal structure such as properties.)

Specified by:

isEquivalent in interface ColumnMetadata

Overrides:

isEquivalent in class AbstractColumnMetadata

columnString

public String columnString()

Description copied from interface: ColumnMetadata

Converts column metadata into string representation accepted by the table schema parser.

Specified by:

columnString in interface ColumnMetadata

Overrides:

columnString in class AbstractColumnMetadata

Returns:

column metadata string representation

typeString

public String typeString()

Description copied from interface: ColumnMetadata

Converts type metadata into string representation accepted by the table schema parser.

Specified by:

typeString in interface ColumnMetadata

Specified by:

typeString in class AbstractColumnMetadata

Returns:

type metadata string representation