Examples of BTree

Home Package Class Method

com.caucho.db.index.BTree
Structure of the table:
```
 b4 - flags b4 - length b8 - parent b8 - next tuples 
```
Structure of a tuple:
```
 b8  - ptr to the actual data key - the tuple's key 
```
For a non-leaf node, the key is the last matching entry in the subtree.
com.db4o.internal.btree.BTree
@exclude
jdbm.btree.BTree
B+Tree persistent indexing data structure. B+Trees are optimized for block-based, random I/O storage because they store multiple keys on one tree node (called BPage). In addition, the leaf nodes directly contain (inline) the values associated with the keys, allowing a single (or sequential) disk read of all the values on the page.
B+Trees are n-airy, yeilding log(N) search cost. They are self-balancing, preventing search performance degradation when the size of the tree grows.
Keys and associated values must be Serializable objects. The user is responsible to supply a serializable Comparator object to be used for the ordering of entries, which are also called Tuple. The B+Tree allows traversing the keys in forward and reverse order using a TupleBrowser obtained from the browse() methods.
This implementation does not directly support duplicate keys, but it is possible to handle duplicates by inlining or referencing an object collection as a value.
There is no limit on key size or value size, but it is recommended to keep both as small as possible to reduce disk I/O. This is especially true for the key size, which impacts all non-leaf BPage objects. @author Alex Boisvert @version $Id: BTree.java,v 1.6 2005/06/25 23:12:31 doomdark Exp $
org.apache.directory.mavibot.btree.BTree
A B-tree interface, to be implemented by the PersistedBTree or the InMemoryBTree @param < K> The Key type @param < V> The Value type @author Apache Directory Project
org.apache.jackrabbit.oak.plugins.index.BTree
A tree allows to query a value for a given key, similar to {@code java.util.SortedMap}.
org.chaidb.db.index.btree.BTree
This class implements Berkeley DB database format.
There are 3 classes:

BTree
Maintains the actual file handle, and answers requests for pages. Auxiliary classes are instantiated with a reference to this class so that they can access the file.
BTreePage
Most database manipulations are handled here. For example, to search, the top-level BTree object fetches the root page (always page 1) from the page file and asks it to search itself. It will go back to the page file to fetch additional pages as needed.
BTreeNode
A fairly simple class that encapsulates the key/data pairs stored in pages.
org.exist.storage.btree.BTree
A general purpose B+-tree which stores binary keys as instances of {@link org.exist.storage.btree.Value}. The actual value data is not stored in the B+tree itself. Instead, we use long pointers to record the storage address of the value. This class has no methods to locate or modify data records. Data handling is in the responsibilty of the proper subclasses: {@link org.exist.storage.index.BFile} and{@link org.exist.storage.dom.DOMFile}. Both, branch and leaf nodes are represented by the inner class {@link org.exist.storage.btree.BTree.BTreeNode}.
org.neo4j.collections.btree.BTree
A b-tree implementation on top of neo4j (using nodes/relationships and properties).
This implementation is not thread safe (yet). This class isn't ready for general usage yet and use of it is discouraged. The implementation isn't thread safe.
org.openrdf.sail.nativerdf.btree.BTree
tvincent.edu/swd/btree/btree.html
http://bluerwhite.org/btree/
http://semaphorecorp.com/btp/algo.html

The first reference was used to implement this class.

TODO: clean up code @author Arjohn Kampman @author Enrico Minack

uk.ac.open.kmi.smartproducts.sesame.sail.btree.BTree

tvincent.edu/swd/btree/btree.html

http://bluerwhite.org/btree/

, and

http://semaphorecorp.com/btp/algo.html

. The first reference was used to implement this class.

TODO: clean up code @author Arjohn Kampman @author Enrico Minack

xbird.storage.index.BTree

BTree represents a Variable Magnitude Simple-Prefix B+Tree File.

@author Makoto YUI (yuin405+xbird@gmail.com)

Examples of uk.ac.open.kmi.smartproducts.sesame.sail.btree.BTree

  private void checkAllCommitted()
    throws IOException
  {
    for (TripleIndex index : indexes) {
      System.out.println("Checking " + index + " index");
      BTree btree = index.getBTree();
      RecordIterator iter = btree.iterateAll();
      try {
        for (byte[] data = iter.next(); data != null; data = iter.next()) {
          byte flags = data[FLAG_IDX];
          boolean wasAdded = (flags & ADDED_FLAG) != 0;
          boolean wasRemoved = (flags & REMOVED_FLAG) != 0;

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Examples of uk.ac.open.kmi.smartproducts.sesame.sail.btree.BTree

    boolean validCache = updatedTriplesCache != null && updatedTriplesCache.isValid();


    byte txnFlagsMask = ~(ADDED_FLAG | REMOVED_FLAG | TOGGLE_EXPLICIT_FLAG);


    for (TripleIndex index : indexes) {
      BTree btree = index.getBTree();


      RecordIterator iter;
      if (validCache) {
        // Use the cached set of updated triples
        iter = updatedTriplesCache.getRecords();
      }
      else {
        // Cache is invalid; too much updates(?). Iterate over all triples
        iter = btree.iterateAll();
      }


      try {
        byte[] data = null;
        while ((data = iter.next()) != null) {
          byte flags = data[FLAG_IDX];
          boolean wasAdded = (flags & ADDED_FLAG) != 0;
          boolean wasRemoved = (flags & REMOVED_FLAG) != 0;
          boolean wasToggled = (flags & TOGGLE_EXPLICIT_FLAG) != 0;


          if (wasAdded) {
            btree.remove(data);
          }
          else {
            if (wasRemoved || wasToggled) {
              data[FLAG_IDX] &= txnFlagsMask;


              if (validCache) {
                // We're iterating the cache
                btree.insert(data);
              }
              else {
                // We're iterating the BTree itself
                iter.set(data);
              }

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Examples of uk.ac.open.kmi.smartproducts.sesame.sail.btree.BTree


    public TripleIndex(String fieldSeq)
      throws IOException
    {
      tripleComparator = new TripleComparator(fieldSeq);
      btree = new BTree(dir, getFilenamePrefix(fieldSeq), 2048, RECORD_LENGTH, tripleComparator, forceSync);
    }

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Examples of xbird.storage.index.BTree

    }


    public void testBplusTreeUniq() throws IOException, DbException {
        File tmpFile = File.createTempFile("btree", ".tmp");
        tmpFile.deleteOnExit();
        BTree btree = new BTree(tmpFile, false);
        btree.create(false);


        List<byte[]> list = new ArrayList<byte[]>(REPEAT);
        Random random = new Random(54552542345L);
        StopWatch sw1 = new StopWatch("[BplusTreeUniq] Index Construction of " + REPEAT);
        for(int i = 0; i < REPEAT; i++) {
            long v = random.nextLong();
            byte[] b = Primitives.toBytes(v);
            Value k = new Value(b);
            Assert.assertTrue(btree.addValue(k, v) == -1);
            list.add(b);
        }
        System.err.println(sw1);


        btree.flush(true, true);


        StopWatch sw2 = new StopWatch("[BplusTreeUniq] Index Search of " + (REPEAT / 2));
        for(int i = REPEAT - 1; i >= 0; i -= 2) {
            byte[] b = list.get(i);
            Assert.assertEquals("#" + i, Primitives.getLong(b), btree.findValue(new Key(b)));
        }
        System.err.println(sw2);
        System.err.println("[BplusTreeUniq] " + tmpFile.getAbsolutePath() + " - size: "
                + tmpFile.length());
        btree.drop();
    }

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Examples of xbird.storage.index.BTree

        this(name, file, false);
    }


    public BTreeIndexer(String name, File file, boolean bulkBuild) {
        this.name = name;
        final BTree tree = new BTree(file, PAGE_SIZE, bulkBuild ? INDEX_BUILD_PAGES
                : IN_MEMORY_PAGES, true);
        try {
            tree.init(bulkBuild);
        } catch (DbException e) {
            throw new IllegalStateException("failed on initializing b+-tree: "
                    + file.getAbsolutePath(), e);
        }
        this.btree = tree;

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Examples of xbird.storage.index.BTree


        public DescriptorBTree(File baseFile, int cacheSize) {
            String descName = baseFile.getName() + DESCRIPTOR_APPENDIX_BTREE;
            File descFile = new File(baseFile.getParent(), descName);
            this.descFile = descFile;
            BTree tree = new BTree(descFile, 2048, cacheSize, false);
            try {
                tree.init(false);
            } catch (DbException e) {
                throw new IllegalStateException("failed on initializing b+-tree: "
                        + descFile.getAbsolutePath(), e);
            }
            this.btree = tree;

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