io.druid.segment.virtual

Class BaseSingleValueDimensionSelector

java.lang.Object

io.druid.segment.virtual.BaseSingleValueDimensionSelector

All Implemented Interfaces:

ColumnValueSelector, DimensionSelector

Direct Known Subclasses:

FloatWrappingDimensionSelector, LongWrappingDimensionSelector

public abstract class BaseSingleValueDimensionSelector
extends Object
implements DimensionSelector

Field Summary

Fields inherited from interface io.druid.segment.DimensionSelector

CARDINALITY_UNKNOWN

Constructor Summary

Constructors

Constructor and Description
BaseSingleValueDimensionSelector()

Method Summary

Modifier and Type	Method and Description
IndexedInts	getRow() Gets all values for the row inside of an IntBuffer.
protected abstract String	getValue()
int	getValueCardinality() Value cardinality is the cardinality of the different occurring values.
IdLookup	idLookup() Returns IdLookup if available for this DimensionSelector, or null.
String	lookupName(int id) The Name is the String name of the actual field.
ValueMatcher	makeValueMatcher(com.google.common.base.Predicate<String> predicate)
ValueMatcher	makeValueMatcher(String value)
boolean	nameLookupPossibleInAdvance() Returns true if it is possible to DimensionSelector.lookupName(int) by ids from 0 to DimensionSelector.getValueCardinality() before the rows with those ids are returned.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

BaseSingleValueDimensionSelector

public BaseSingleValueDimensionSelector()

Method Detail

getValue

protected abstract String getValue()

getRow

public IndexedInts getRow()

Description copied from interface: DimensionSelector

Gets all values for the row inside of an IntBuffer. I.e. one possible implementation could be return IntBuffer.wrap(lookupExpansion(get());

Specified by:

getRow in interface DimensionSelector

Returns:

all values for the row as an IntBuffer

getValueCardinality

public int getValueCardinality()

Description copied from interface: DimensionSelector

Value cardinality is the cardinality of the different occurring values. If there were 4 rows: A,B A B A Value cardinality would be 2. Cardinality may be unknown (e.g. the selector used by IncrementalIndex while reading input rows), in which case this method will return -1. If cardinality is unknown, you should assume this dimension selector has no dictionary, and avoid storing ids, calling "lookupId", or calling "lookupName" outside of the context of operating on a single row.

Specified by:

getValueCardinality in interface DimensionSelector

Returns:

the value cardinality, or -1 if unknown.

lookupName

public String lookupName(int id)

Description copied from interface: DimensionSelector

The Name is the String name of the actual field. It is assumed that storage layers convert names into id values which can then be used to get the string value. For example A,B A A,B B getRow() would return getRow(0) => [0 1] getRow(1) => [0] getRow(2) => [0 1] getRow(3) => [1] and then lookupName would return: lookupName(0) => A lookupName(1) => B

Specified by:

lookupName in interface DimensionSelector

Parameters:

id - id to lookup the field name for

Returns:

the field name for the given id

makeValueMatcher

public ValueMatcher makeValueMatcher(String value)

Specified by:

makeValueMatcher in interface DimensionSelector

Parameters:

value - nullable dimension value

makeValueMatcher

public ValueMatcher makeValueMatcher(com.google.common.base.Predicate<String> predicate)

Specified by:

makeValueMatcher in interface DimensionSelector

nameLookupPossibleInAdvance

public boolean nameLookupPossibleInAdvance()

Description copied from interface: DimensionSelector

Returns true if it is possible to DimensionSelector.lookupName(int) by ids from 0 to DimensionSelector.getValueCardinality() before the rows with those ids are returned.

Returns false if DimensionSelector.lookupName(int) could be called with ids, returned from the most recent call of DimensionSelector.getRow() on this DimensionSelector, but not earlier. If DimensionSelector.getValueCardinality() of this DimensionSelector additionally returns DimensionSelector.CARDINALITY_UNKNOWN, lookupName() couldn't be called with ids, returned by not the most recent call of DimensionSelector.getRow(), i. e. names for ids couldn't be looked up "later". If DimensionSelector.getValueCardinality() returns a non-negative number, lookupName() could be called with any ids, returned from #getRow() since the creation of this DimensionSelector.

If DimensionSelector.lookupName(int) is called with an ineligible id, result is undefined: exception could be thrown, or null returned, or some other random value.

Specified by:

nameLookupPossibleInAdvance in interface DimensionSelector

idLookup

@Nullable
public IdLookup idLookup()

Description copied from interface: DimensionSelector

Returns IdLookup if available for this DimensionSelector, or null.

Specified by:

idLookup in interface DimensionSelector