Package com.apple.foundationdb.record.metadata.expressions

Class GroupingKeyExpression

java.lang.Object

com.apple.foundationdb.record.metadata.expressions.BaseKeyExpression

com.apple.foundationdb.record.metadata.expressions.GroupingKeyExpression

All Implemented Interfaces:

KeyExpression, KeyExpressionWithChild, KeyExpressionWithChildren, PlanHashable, QueryHashable

@API(MAINTAINED)
public class GroupingKeyExpression
extends BaseKeyExpression
implements KeyExpressionWithChild

A key expression that divides into two parts for the sake of aggregate or rank indexing. Zero or more grouping columns determine a subindex within which an aggregate or ranking is maintained. The remaining (up to Index.getColumnSize()) grouped columns are the value to be aggregated / ranked.

Nested Class Summary

Nested classes/interfaces inherited from class com.apple.foundationdb.record.metadata.expressions.BaseKeyExpression

BaseKeyExpression.IllegalSubKeyException, BaseKeyExpression.UnsplittableKeyExpressionException

Nested classes/interfaces inherited from interface com.apple.foundationdb.record.metadata.expressions.KeyExpression

KeyExpression.DeserializationException, KeyExpression.FanType, KeyExpression.InvalidExpressionException, KeyExpression.InvalidResultException, KeyExpression.NoSuchArgumentException, KeyExpression.SerializationException

Nested classes/interfaces inherited from interface com.apple.foundationdb.record.PlanHashable

PlanHashable.PlanHashKind

Nested classes/interfaces inherited from interface com.apple.foundationdb.record.QueryHashable

QueryHashable.QueryHashKind

Constructor Summary

Constructors

Constructor	Description
GroupingKeyExpression(KeyExpression wholeKey, int groupedCount)
GroupingKeyExpression(RecordMetaDataProto.Grouping grouping)

Method Summary

Modifier and Type	Method	Description
boolean	createsDuplicates()	This states whether the given expression type is capable of evaluating more to more than one value when applied to a single record.
boolean	equals(Object o)
<M extends Message> List<Key.Evaluated>	evaluateMessage(FDBRecord<M> record, Message message)	Evaluate this expression against a record or a Protobuf message.
<S extends KeyExpressionVisitor.State> GraphExpansion	expand(ExpansionVisitor<S> visitor)	Expand this key expression into a data flow graph.
KeyExpression	getChild()
int	getColumnSize()	Returns the number of items in each KeyValue that will be returned.
int	getGroupedCount()
KeyExpression	getGroupedSubKey()
int	getGroupingCount()	Get number of leading columns that select the group (e.g., ranked set or atomic aggregate); remaining fields are the value (e.g., score) within the set.
KeyExpression	getGroupingSubKey()
KeyExpression	getWholeKey()
int	hashCode()
boolean	hasRecordTypeKey()	Check whether a key expression uses record type key in some way.
List<KeyExpression>	normalizeKeyForPositions()	Get key in normalized form for comparing field-by-field.
static GroupingKeyExpression	of(KeyExpression groupedValue, KeyExpression groupByFirst, KeyExpression... groupByRest)
int	planHash(PlanHashable.PlanHashKind hashKind)	Return a hash similar to hashCode, but with the additional guarantee that is is stable across JVMs.
int	queryHash(QueryHashable.QueryHashKind hashKind)	Return a hash similar to hashCode, but with the additional guarantee that is is stable across JVMs.
RecordMetaDataProto.KeyExpression	toKeyExpression()
RecordMetaDataProto.Grouping	toProto()
String	toString()
List<Descriptors.FieldDescriptor>	validate(Descriptors.Descriptor descriptor)	Validate this expression against a given record type descriptor.
int	versionColumns()	Returns the number of version columns produced by this key expression.

Methods inherited from class com.apple.foundationdb.record.metadata.expressions.BaseKeyExpression

getSubKey, getSubKeyImpl, isPrefixKey

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.apple.foundationdb.record.metadata.expressions.KeyExpression

evaluate, evaluateSingleton, getSubKey, hasLosslessNormalization, hasProperInterfaces, isPrefixKey

Methods inherited from interface com.apple.foundationdb.record.metadata.expressions.KeyExpressionWithChild

getChildren

Methods inherited from interface com.apple.foundationdb.record.PlanHashable

planHash

Constructor Detail

GroupingKeyExpression

public GroupingKeyExpression(@Nonnull
                             KeyExpression wholeKey,
                             int groupedCount)

GroupingKeyExpression

public GroupingKeyExpression(@Nonnull
                             RecordMetaDataProto.Grouping grouping)
                      throws KeyExpression.DeserializationException

Throws:

KeyExpression.DeserializationException

Method Detail

of

public static GroupingKeyExpression of(@Nonnull
                                       KeyExpression groupedValue,
                                       @Nonnull
                                       KeyExpression groupByFirst,
                                       @Nonnull
                                       KeyExpression... groupByRest)

evaluateMessage

@Nonnull
public <M extends Message> List<Key.Evaluated> evaluateMessage(@Nullable
                                                               FDBRecord<M> record,
                                                               @Nullable
                                                               Message message)

Description copied from interface: KeyExpression

Evaluate this expression against a record or a Protobuf message. The message might be the Protobuf form of a record or a piece of that record. If the key expression is meaningful against a subrecord, it should evaluate against the message. Otherwise, it should evaluate against the record and ignore what part of that record is being considered. There should not be any reason to call this method outside of the implementation of another evaluateMessage. Under ordinary circumstances, if record is null, then message will be null. Otherwise, message will be record.getRecord() or some submessage of that, possibly null if the corresponding field is missing.

Specified by:

evaluateMessage in interface KeyExpression

Type Parameters:

M - the type of record

Parameters:

record - the record

message - the Protobuf message to evaluate against

Returns:

the evaluated keys for the given record

See Also:

KeyExpression.evaluate(com.apple.foundationdb.record.provider.foundationdb.FDBRecord<M>)

createsDuplicates

public boolean createsDuplicates()

Description copied from interface: KeyExpression

This states whether the given expression type is capable of evaluating more to more than one value when applied to a single record. In practice, this can happen if this expression is evaluated on a repeated field with FanType.FanOut set (either directly or indirectly).

Specified by:

createsDuplicates in interface KeyExpression

Returns:

true if this expression can evaluate to multiple values and false otherwise

validate

public List<Descriptors.FieldDescriptor> validate(@Nonnull
                                                  Descriptors.Descriptor descriptor)

Description copied from interface: KeyExpression

Validate this expression against a given record type descriptor.

Specified by:

validate in interface KeyExpression

Parameters:

descriptor - the descriptor for the record type or submessage

Returns:

a list of fields that this key applies to

getColumnSize

public int getColumnSize()

Description copied from interface: KeyExpression

Returns the number of items in each KeyValue that will be returned. For key expressions that support KeyExpression.FanType.Concatenate, this will the count of non-nested lists, i.e. this will be value of evaluate(r).get(i).toList().size() for any i or r.

Specified by:

getColumnSize in interface KeyExpression

Returns:

the number of elements that will be produced for every key

toProto

@Nonnull
public RecordMetaDataProto.Grouping toProto()
                                     throws KeyExpression.SerializationException

Specified by:

toProto in interface KeyExpression

Throws:

KeyExpression.SerializationException

toKeyExpression

@Nonnull
public RecordMetaDataProto.KeyExpression toKeyExpression()

Specified by:

toKeyExpression in interface KeyExpression

normalizeKeyForPositions

@Nonnull
public List<KeyExpression> normalizeKeyForPositions()

Description copied from interface: KeyExpression

Get key in normalized form for comparing field-by-field. Does not take account of fan-type, so only valid when this has already been taken care of, such as individual index entries.

Specified by:

normalizeKeyForPositions in interface KeyExpression

Returns:

a list of key expressions in order

expand

@Nonnull
public <S extends KeyExpressionVisitor.State> GraphExpansion expand(@Nonnull
                                                                    ExpansionVisitor<S> visitor)

Description copied from interface: KeyExpression

Expand this key expression into a data flow graph. The returned graph represents an adequate representation of the key expression as composition of relational expressions and operators (RelationalExpressions). Note that implementors should defer to the visitation methods in the supplied visitor rather than encoding actual logic in an overriding method.

Specified by:

expand in interface KeyExpression

Type Parameters:

S - a type that reflects the state that visitor uses

Parameters:

visitor - a ExpansionVisitor that is created by the caller from a data structure that reflects the specific semantics of the key expression. Normally this visitor is directly created based on an index.

Returns:

a new GraphExpansion representing the query graph equivalent of this key expression using the supplied visitor

See Also:

QueryComponent.expand(com.apple.foundationdb.record.query.plan.temp.CorrelationIdentifier)

versionColumns

public int versionColumns()

Description copied from interface: KeyExpression

Returns the number of version columns produced by this key expression.

Specified by:

versionColumns in interface KeyExpression

Returns:

the number of version columns

hasRecordTypeKey

public boolean hasRecordTypeKey()

Description copied from interface: KeyExpression

Check whether a key expression uses record type key in some way.

Specified by:

hasRecordTypeKey in interface KeyExpression

Returns:

true if record type key is used

getWholeKey

@Nonnull
public KeyExpression getWholeKey()

getChild

@Nonnull
public KeyExpression getChild()

Specified by:

getChild in interface KeyExpressionWithChild

getGroupedCount

public int getGroupedCount()

getGroupingCount

public int getGroupingCount()

Get number of leading columns that select the group (e.g., ranked set or atomic aggregate); remaining fields are the value (e.g., score) within the set.

Returns:

the number of leading columns that select the group

See Also:

getGroupedCount()

getGroupedSubKey

@Nonnull
public KeyExpression getGroupedSubKey()

getGroupingSubKey

@Nonnull
public KeyExpression getGroupingSubKey()

toString

public String toString()

Overrides:

toString in class Object

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

planHash

public int planHash(@Nonnull
                    PlanHashable.PlanHashKind hashKind)

Description copied from interface: PlanHashable

Return a hash similar to hashCode, but with the additional guarantee that is is stable across JVMs.

Specified by:

planHash in interface PlanHashable

Parameters:

hashKind - the "kind" of hash to calculate. Each kind of hash has a particular logic with regards to included and excluded items.

Returns:

a stable hash code

queryHash

public int queryHash(@Nonnull
                     QueryHashable.QueryHashKind hashKind)

Description copied from interface: QueryHashable

Return a hash similar to hashCode, but with the additional guarantee that is is stable across JVMs.

Specified by:

queryHash in interface QueryHashable

Parameters:

hashKind - the "kind" of hash to calculate. Each kind of hash has a particular logic with regards to included and excluded items.

Returns:

a stable hash code