com.apple.foundationdb.record.metadata.expressions

Class SplitKeyExpression

java.lang.Object

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

com.apple.foundationdb.record.metadata.expressions.SplitKeyExpression

All Implemented Interfaces:

AtomKeyExpression, KeyExpression, KeyExpressionWithoutChildren, PlanHashable, Bindable, PlannerExpression

@API(value=MAINTAINED)
public class SplitKeyExpression
extends BaseKeyExpression
implements AtomKeyExpression, KeyExpressionWithoutChildren

Turn a key with repeated single values into multiple Key.Evaluated containing several of the values. For example, 12 values with splitSize 3 turns into 4 Key.Evaluated. The same result can be achieved more transparently by having a repeated nested submessage with the several fields in it; this is for the sake of clients with poorer type systems that only allow for lists of primitive types.

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

Constructor Summary

Constructors

Constructor and Description
SplitKeyExpression(KeyExpression joined, int splitSize)
SplitKeyExpression(RecordMetaDataProto.Split split)

Method Summary

Modifier and Type	Method and 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)
boolean	equalsAtomic(AtomKeyExpression other)
boolean	equivalentForSort(KeyExpression other) Check whether a key expression is the same for purposes of determining sort order.
<M extends Message> List<Key.Evaluated>	evaluateMessage(FDBRecord<M> record, Message message) Evaluate this expression against a record or a Protobuf message.
int	getColumnSize() Returns the number of items in each KeyValue that will be returned.
KeyExpression	getJoined()
Iterator<? extends ExpressionRef<? extends PlannerExpression>>	getPlannerExpressionChildren() Return an iterator of references to the children of this planner expression.
GroupingKeyExpression	groupBy(KeyExpression groupByFirst, KeyExpression... groupByRest)
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.
int	planHash() Return a hash similar to hashCode, but with the additional guarantee that is is stable across JVMs.
RecordMetaDataProto.KeyExpression	toKeyExpression()
RecordMetaDataProto.Split	toProto()
String	toString()
GroupingKeyExpression	ungrouped() Get this entire split as a group without any grouping keys.
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, fromProto, getSubKey, hasProperInterfaces, isPrefixKey

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

iterablePlanHash, objectPlanHash, objectsPlanHash, planHash, planHash

Methods inherited from interface com.apple.foundationdb.record.query.plan.temp.PlannerExpression

acceptPropertyVisitor, bindTo

Constructor Detail

SplitKeyExpression

public SplitKeyExpression(KeyExpression joined,
                          int splitSize)

SplitKeyExpression

public SplitKeyExpression(@Nonnull
                          RecordMetaDataProto.Split split)
                   throws KeyExpression.DeserializationException

Throws:

KeyExpression.DeserializationException

Method Detail

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.Split 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

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

getJoined

@Nonnull
public KeyExpression getJoined()

ungrouped

@Nonnull
public GroupingKeyExpression ungrouped()

Get this entire split as a group without any grouping keys.

Returns:

this split without any grouping keys

groupBy

@Nonnull
public GroupingKeyExpression groupBy(@Nonnull
                                              KeyExpression groupByFirst,
                                              @Nonnull
                                              KeyExpression... groupByRest)

getPlannerExpressionChildren

@Nonnull
 @API(value=EXPERIMENTAL)
public Iterator<? extends ExpressionRef<? extends PlannerExpression>> getPlannerExpressionChildren()

Description copied from interface: PlannerExpression

Return an iterator of references to the children of this planner expression. The iterators returned by different calls are guaranteed to be independent (i.e., advancing one will not advance another). However, they might point to the same object, as when Collections.emptyIterator() is returned. The returned iterator should be treated as an immutable object and may throw an exception if Iterator.remove() is called. The iterator must return its elements in a consistent order.

Specified by:

getPlannerExpressionChildren in interface PlannerExpression

Returns:

an iterator of references to the children of this planner expression

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()

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

Returns:

a stable hash code

equalsAtomic

public boolean equalsAtomic(AtomKeyExpression other)

Specified by:

equalsAtomic in interface AtomKeyExpression

equivalentForSort

public boolean equivalentForSort(@Nonnull
                                 KeyExpression other)

Description copied from interface: KeyExpression

Check whether a key expression is the same for purposes of determining sort order.

Specified by:

equivalentForSort in interface KeyExpression

Parameters:

other - another key expression

Returns:

true if this key expression sorts entries in the same order