com.bigdata.btree

Interface ISimpleBTree

All Known Subinterfaces:

IClientIndex, IIndex, ILocalBTreeView, IScaleOutClientIndex

All Known Implementing Classes:

AbstractBTree, AbstractCommitTimeIndex, AbstractScaleOutClientIndexView, AbstractScaleOutClientIndexView2, BTree, ClientIndexView, ClientIndexViewRefactor, CommitRecordIndex, CommitTimeIndex, CounterSetBTree, DelegateBTree, DelegateIndex, EventReceiver.EventBTree, FusedView, IndexSegment, IndexSegmentIndex, IsolatedFusedView, JournalIndex, MetadataIndex, MetadataIndexView, Name2Addr, ReadCommittedView, ReadOnlyIndex, TestMROWTransactions.MyBTree, TestRestartSafe.MyBTree, TxId2CommitTimeIndex, UnisolatedReadWriteIndex

public interface ISimpleBTree

Interface for non-batch operations on a B+-Tree mapping non-null variable length unsigned byte[] keys to arbitrary values.

Author:

Bryan Thompson

See Also:

UnicodeKeyBuilder, which may be used to encode one or more primitive data type values or Unicode strings into a variable length unsigned byte[] key.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	contains(byte[] key) Return true iff there is a (non-deleted) index entry for the key.
byte[]	insert(byte[] key, byte[] value) Insert or update a value under the key.
byte[]	lookup(byte[] key) Lookup a value for a key.
byte[]	putIfAbsent(byte[] key, byte[] value) Insert or update a value under the key iff there is no entry for that key in the index.
byte[]	remove(byte[] key) Remove the key and its associated value.

Method Detail

insert

byte[] insert(byte[] key,
            byte[] value)

Insert or update a value under the key.

Parameters:

key - The key.

value - The value (may be null).

Returns:

The previous value under that key or null if the key was not found or if the previous entry for that key was marked as deleted.

putIfAbsent

byte[] putIfAbsent(byte[] key,
                 byte[] value)

Insert or update a value under the key iff there is no entry for that key in the index. This is equivalent to

 if (!contains(key))
        insert(key, value);
 

However, if the index allows null values to be stored under a key and the application in fact stores null values for some tuples, then caller is not able to decide using this method whether or not the mutation was applied based on the return value. For these cases if the caller needs to know whether or not the conditional mutation actually took place, the caller CAN use the pattern if(!contains()) insert(key,value); to obtain that information.

Parameters:

key - The key.

value - The value (may be null).

Returns:

The previous value under that key or null if the key was not found or if the previous entry for that key was marked as deleted. Note that the return value MAY be null even if there was an entry under the key. This is because the index is capable of storing a null value. In such cases the conditional mutation WAS NOT applied.

See Also:

(putIfAbsent)

lookup

byte[] lookup(byte[] key)

Lookup a value for a key.

Returns:

The value stored under that key or null if there is no entry for that key or if the entry under that key is marked as deleted.

contains

boolean contains(byte[] key)

Return true iff there is a (non-deleted) index entry for the key. An index entry with a null value will cause this method to return true. A deleted index entry will cause this method to return false.

Parameters:

key - The key.

Returns:

true if the index contains an (un-deleted) entry for that key.

remove

byte[] remove(byte[] key)

Remove the key and its associated value.

Parameters:

key - The key.

Returns:

The value stored under that key or null if the key was not found or if the previous entry under that key was marked as deleted.