com.apple.foundationdb.record.metadata.expressions

Class RecordTypeKeyExpression

java.lang.Object

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

com.apple.foundationdb.record.metadata.expressions.RecordTypeKeyExpression

All Implemented Interfaces:

AtomKeyExpression, KeyExpression, KeyExpressionWithoutChildren, PlanHashable, Bindable, PlannerExpression

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

A key expression that indicates that a unique record type identifier should be contained within the key. The unique value can be specified explicitly or generated automatically from the corresponding field numbers in the union message descriptor. It is important that the unique identifiers are stable. A record type's identifier should never change. If it is automatically generated, that means that fields should never be removed / reused in the union message descriptor, but at most deprecated. In that way, the lowest numbered field for a given type will always be the same. If the record type key appears at the start of every primary key, the record extent is divided by type, as in other database systems.

See Also:

RecordType.getExplicitRecordTypeKey(), RecordMetaData.primaryKeyHasRecordTypePrefix()

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

Field Summary

Fields

Modifier and Type	Field and Description
static RecordTypeKeyExpression	RECORD_TYPE_KEY
static RecordMetaDataProto.KeyExpression	RECORD_TYPE_KEY_PROTO

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)
<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.
Iterator<? extends ExpressionRef<? extends PlannerExpression>>	getPlannerExpressionChildren() Return an iterator of references to the children of this planner expression.
int	hashCode()
boolean	hasRecordTypeKey() Check whether a key expression uses record type key in some way.
int	planHash() Return a hash similar to hashCode, but with the additional guarantee that is is stable across JVMs.
RecordMetaDataProto.KeyExpression	toKeyExpression()
RecordMetaDataProto.RecordTypeKey	toProto()
String	toString()
GroupingKeyExpression	ungrouped() A RecordType expression with no grouping keys (mostly for evaluating record functions).
List<Descriptors.FieldDescriptor>	validate(Descriptors.Descriptor descriptor) Validate this expression against a given record type descriptor.

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, normalizeKeyForPositions, versionColumns

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

Field Detail

RECORD_TYPE_KEY

public static final RecordTypeKeyExpression RECORD_TYPE_KEY

RECORD_TYPE_KEY_PROTO

public static final RecordMetaDataProto.KeyExpression RECORD_TYPE_KEY_PROTO

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. When we support 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

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

ungrouped

@Nonnull
public GroupingKeyExpression ungrouped()

A RecordType expression with no grouping keys (mostly for evaluating record functions).

Returns:

a GroupingKeyExpression with no grouping keys

toProto

@Nonnull
public RecordMetaDataProto.RecordTypeKey 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

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

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

toString

public String toString()

Overrides:

toString in class Object