<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <!--NewPage--> <HTML> <HEAD> <!-- Generated by javadoc (build 1.6.0_0) on Wed Dec 30 04:50:33 EST 2009 --> <TITLE> EntityIndex </TITLE> <META NAME="date" CONTENT="2009-12-30"> <LINK REL ="stylesheet" TYPE="text/css" HREF="../../../stylesheet.css" TITLE="Style"> <SCRIPT type="text/javascript"> function windowTitle() { if (location.href.indexOf('is-external=true') == -1) { parent.document.title="EntityIndex"; } } </SCRIPT> <NOSCRIPT> </NOSCRIPT> </HEAD> <BODY BGCOLOR="white" onload="windowTitle();"> <HR> <!-- ========= START OF TOP NAVBAR ======= --> <A NAME="navbar_top"><!-- --></A> <A HREF="#skip-navbar_top" title="Skip navigation links"></A> <TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0" SUMMARY=""> <TR> <TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A NAME="navbar_top_firstrow"><!-- --></A> <TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3" SUMMARY=""> <TR ALIGN="center" VALIGN="top"> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../overview-summary.html"><FONT CLASS="NavBarFont1"><B>Overview</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-summary.html"><FONT CLASS="NavBarFont1"><B>Package</B></FONT></A> </TD> <TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> <FONT CLASS="NavBarFont1Rev"><B>Class</B></FONT> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-tree.html"><FONT CLASS="NavBarFont1"><B>Tree</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../deprecated-list.html"><FONT CLASS="NavBarFont1"><B>Deprecated</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../index-all.html"><FONT CLASS="NavBarFont1"><B>Index</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../help-doc.html"><FONT CLASS="NavBarFont1"><B>Help</B></FONT></A> </TD> </TR> </TABLE> </TD> <TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM> </EM> </TD> </TR> <TR> <TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../../com/sleepycat/persist/EntityCursor.html" title="interface in com.sleepycat.persist"><B>PREV CLASS</B></A> <A HREF="../../../com/sleepycat/persist/EntityJoin.html" title="class in com.sleepycat.persist"><B>NEXT CLASS</B></A></FONT></TD> <TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../../index.html?com/sleepycat/persist/EntityIndex.html" target="_top"><B>FRAMES</B></A> <A HREF="EntityIndex.html" target="_top"><B>NO FRAMES</B></A> <SCRIPT type="text/javascript"> <!-- if(window==top) { document.writeln('<A HREF="../../../allclasses-noframe.html"><B>All Classes</B></A>'); } //--> </SCRIPT> <NOSCRIPT> <A HREF="../../../allclasses-noframe.html"><B>All Classes</B></A> </NOSCRIPT> </FONT></TD> </TR> <TR> <TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> SUMMARY: NESTED | FIELD | CONSTR | <A HREF="#method_summary">METHOD</A></FONT></TD> <TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> DETAIL: FIELD | CONSTR | <A HREF="#method_detail">METHOD</A></FONT></TD> </TR> </TABLE> <A NAME="skip-navbar_top"></A> <!-- ========= END OF TOP NAVBAR ========= --> <HR> <!-- ======== START OF CLASS DATA ======== --> <H2> <FONT SIZE="-1"> com.sleepycat.persist</FONT> <BR> Interface EntityIndex<K,V></H2> <DL> <DT><B>All Known Implementing Classes:</B> <DD><A HREF="../../../com/sleepycat/persist/PrimaryIndex.html" title="class in com.sleepycat.persist">PrimaryIndex</A>, <A HREF="../../../com/sleepycat/persist/SecondaryIndex.html" title="class in com.sleepycat.persist">SecondaryIndex</A></DD> </DL> <HR> <DL> <DT><PRE>public interface <B>EntityIndex<K,V></B></DL> </PRE> <P> The interface for accessing keys and entities via a primary or secondary index. <p><code>EntityIndex</code> objects are thread-safe. Multiple threads may safely call the methods of a shared <code>EntityIndex</code> object.</p> <p>An index is conceptually a <em>map</em>. {key:value} mappings are stored in the index and accessed by key. In fact, for interoperability with other libraries that use the standard Java <CODE>Map</CODE> or <CODE>SortedMap</CODE> interfaces, an <code>EntityIndex</code> may be accessed via these standard interfaces by calling the <A HREF="../../../com/sleepycat/persist/EntityIndex.html#map()"><CODE>map()</CODE></A> or <A HREF="../../../com/sleepycat/persist/EntityIndex.html#sortedMap()"><CODE>sortedMap()</CODE></A> methods.</p> <p><code>EntityIndex</code> is an interface that is implemented by several classes in this package for different purposes. Depending on the context, the key type (K) and value type (V) of the index take on different meanings. The different classes that implement <code>EntityIndex</code> are:</p> <ul> <li><A HREF="../../../com/sleepycat/persist/PrimaryIndex.html" title="class in com.sleepycat.persist"><CODE>PrimaryIndex</CODE></A> maps primary keys to entities.</li> <li><A HREF="../../../com/sleepycat/persist/SecondaryIndex.html" title="class in com.sleepycat.persist"><CODE>SecondaryIndex</CODE></A> maps secondary keys to entities.</li> <li><A HREF="../../../com/sleepycat/persist/SecondaryIndex.html#keysIndex"><CODE>SecondaryIndex.keysIndex</CODE></A> maps secondary keys to primary keys.</li> <li><A HREF="../../../com/sleepycat/persist/SecondaryIndex.html#subIndex(SK)"><CODE>SecondaryIndex.subIndex(SK)</CODE></A> maps primary keys to entities, for the subset of entities having a specified secondary key.</li> </ul> <p>In all cases, the index key type (K) is a primary or secondary key class. The index value type (V) is an entity class in all cases except for a <A HREF="../../../com/sleepycat/persist/SecondaryIndex.html#keysIndex"><CODE>SecondaryIndex.keysIndex</CODE></A>, when it is a primary key class.</p> <p>In the following example, a <code>Employee</code> entity with a <code>MANY_TO_ONE</code> secondary key is defined.</p> <pre class="code"> @Entity class Employee { @PrimaryKey long id; @SecondaryKey(relate=MANY_TO_ONE) String department; String name; private Employee() {} }</pre> <p>Consider that we have stored the entities below:</p> <p><table class="code" border="1"> <tr><th colspan="3">Entities</th></tr> <tr><th>ID</th><th>Department</th><th>Name</th></tr> <tr><td>1</td><td>Engineering</td><td>Jane Smith</td></tr> <tr><td>2</td><td>Sales</td><td>Joan Smith</td></tr> <tr><td>3</td><td>Engineering</td><td>John Smith</td></tr> <tr><td>4</td><td>Sales</td><td>Jim Smith</td></tr> </table></p> <p><A HREF="../../../com/sleepycat/persist/PrimaryIndex.html" title="class in com.sleepycat.persist"><CODE>PrimaryIndex</CODE></A> maps primary keys to entities:</p> <pre class="code"> <code>PrimaryIndex<Long,Employee></code> primaryIndex = store.getPrimaryIndex(Long.class, Employee.class);</pre> <p><table class="code" border="1"> <tr><th colspan="4">primaryIndex</th></tr> <tr><th>Primary Key</th><th colspan="3">Entity</th></tr> <tr><td>1</td><td>1</td><td>Engineering</td><td>Jane Smith</td></tr> <tr><td>2</td><td>2</td><td>Sales</td><td>Joan Smith</td></tr> <tr><td>3</td><td>3</td><td>Engineering</td><td>John Smith</td></tr> <tr><td>4</td><td>4</td><td>Sales</td><td>Jim Smith</td></tr> </table></p> <p><A HREF="../../../com/sleepycat/persist/SecondaryIndex.html" title="class in com.sleepycat.persist"><CODE>SecondaryIndex</CODE></A> maps secondary keys to entities:</p> <pre class="code"> <code>SecondaryIndex<String,Long,Employee></code> secondaryIndex = store.getSecondaryIndex(primaryIndex, String.class, "department");</pre> <p><table class="code" border="1"> <tr><th colspan="4">secondaryIndex</th></tr> <tr><th>Secondary Key</th><th colspan="3">Entity</th></tr> <tr><td>Engineering</td><td>1</td><td>Engineering</td><td>Jane Smith</td></tr> <tr><td>Engineering</td><td>3</td><td>Engineering</td><td>John Smith</td></tr> <tr><td>Sales</td><td>2</td><td>Sales</td><td>Joan Smith</td></tr> <tr><td>Sales</td><td>4</td><td>Sales</td><td>Jim Smith</td></tr> </table></p> <p><A HREF="../../../com/sleepycat/persist/SecondaryIndex.html#keysIndex"><CODE>SecondaryIndex.keysIndex</CODE></A> maps secondary keys to primary keys:</p> <pre class="code"> <code>EntityIndex<String,Long></code> keysIndex = secondaryIndex.keysIndex();</pre> <p><table class="code" border="1"> <tr><th colspan="4">keysIndex</th></tr> <tr><th>Secondary Key</th><th colspan="3">Primary Key</th></tr> <tr><td>Engineering</td><td>1</td></tr> <tr><td>Engineering</td><td>3</td></tr> <tr><td>Sales</td><td>2</td></tr> <tr><td>Sales</td><td>4</td></tr> </table></p> <p><A HREF="../../../com/sleepycat/persist/SecondaryIndex.html#subIndex(SK)"><CODE>SecondaryIndex.subIndex(SK)</CODE></A> maps primary keys to entities, for the subset of entities having a specified secondary key:</p> <pre class="code"> <code>EntityIndex<Long,Entity></code> subIndex = secondaryIndex.subIndex("Engineering");</pre> <p><table class="code" border="1"> <tr><th colspan="4">subIndex</th></tr> <tr><th>Primary Key</th><th colspan="3">Entity</th></tr> <tr><td>1</td><td>1</td><td>Engineering</td><td>Jane Smith</td></tr> <tr><td>3</td><td>3</td><td>Engineering</td><td>John Smith</td></tr> </table></p> <h3>Accessing the Index</h3> <p>An <code>EntityIndex</code> provides a variety of methods for retrieving entities from an index. It also provides methods for deleting entities. However, it does not provide methods for inserting and updating. To insert and update entities, use the <A HREF="../../../com/sleepycat/persist/PrimaryIndex.html#put(E)"><CODE>PrimaryIndex.put(E)</CODE></A> family of methods in the <A HREF="../../../com/sleepycat/persist/PrimaryIndex.html" title="class in com.sleepycat.persist"><CODE>PrimaryIndex</CODE></A> class.</p> <p>An <code>EntityIndex</code> supports two mechanisms for retrieving entities:</p> <ol> <li>The <A HREF="../../../com/sleepycat/persist/EntityIndex.html#get(K)"><CODE>get(K)</CODE></A> method returns a single value for a given key. If there are multiple values with the same secondary key (duplicates), it returns the first entity in the duplicate set.</li> <li>An <A HREF="../../../com/sleepycat/persist/EntityCursor.html" title="interface in com.sleepycat.persist"><CODE>EntityCursor</CODE></A> can be obtained using the <A HREF="../../../com/sleepycat/persist/EntityIndex.html#keys()"><CODE>keys()</CODE></A> and <A HREF="../../../com/sleepycat/persist/EntityIndex.html#entities()"><CODE>entities()</CODE></A> family of methods. A cursor can be used to return all values in the index, including duplicates. A cursor can also be used to return values within a specified range of keys.</li> </ol> <p>Using the example entities above, calling <A HREF="../../../com/sleepycat/persist/EntityIndex.html#get(K)"><CODE>get(K)</CODE></A> on the primary index will always return the employee with the given ID, or null if no such ID exists. But calling <A HREF="../../../com/sleepycat/persist/EntityIndex.html#get(K)"><CODE>get(K)</CODE></A> on the secondary index will retrieve the first employee in the given department, which may not be very useful:</p> <pre class="code"> Employee emp = primaryIndex.get(1); // Returns by unique ID emp = secondaryIndex.get("Engineering"); // Returns first in department</pre> <p>Using a cursor, you can iterate through all duplicates in the secondary index:</p> <pre class="code"> <code>EntityCursor<Employee></code> cursor = secondaryIndex.entities(); try { for (Employee entity : cursor) { if (entity.department.equals("Engineering")) { // Do something with the entity... } } } finally { cursor.close(); }</pre> <p>But for a large database it is much more efficient to iterate over only those entities with the secondary key you're searching for. This could be done by restricting a cursor to a range of keys:</p> <pre class="code"> <code>EntityCursor<Employee></code> cursor = secondaryIndex.entities("Engineering", true, "Engineering", true); try { for (Employee entity : cursor) { // Do something with the entity... } } finally { cursor.close(); }</pre> <p>However, when you are interested only in the entities with a particular secondary key value, it is more convenient to use a sub-index:</p> <pre class="code"> <code>EntityIndex<Long,Entity></code> subIndex = secondaryIndex.subIndex("Engineering"); <code>EntityCursor<Employee></code> cursor = subIndex.entities(); try { for (Employee entity : cursor) { // Do something with the entity... } } finally { cursor.close(); }</pre> <p>In addition to being more convenient than a cursor range, a sub-index allows retrieving by primary key:</p> <pre class="code"> Employee emp = subIndex.get(1);</pre> <p>When using a sub-index, all operations performed on the sub-index are restricted to the single key that was specified when the sub-index was created. For example, the following returns null because employee 2 is not in the Engineering department and therefore is not part of the sub-index:</p> <pre class="code"> Employee emp = subIndex.get(2);</pre> <p>For more information on using cursors and cursor ranges, see <A HREF="../../../com/sleepycat/persist/EntityCursor.html" title="interface in com.sleepycat.persist"><CODE>EntityCursor</CODE></A>.</p> <p>Note that when using an index, keys and values are stored and retrieved by value not by reference. In other words, if an entity object is stored and then retrieved, or retrieved twice, each object will be a separate instance. For example, in the code below the assertion will always fail.</p> <pre class="code"> MyKey key = ...; MyEntity entity1 = index.get(key); MyEntity entity2 = index.get(key); assert entity1 == entity2; // always fails! </pre> <h3>Deleting from the Index</h3> <p>Any type of index may be used to delete entities with a specified key by calling <A HREF="../../../com/sleepycat/persist/EntityIndex.html#delete(K)"><CODE>delete(K)</CODE></A>. The important thing to keep in mind is that <em>all entities</em> with the specified key are deleted. In a primary index, at most a single entity is deleted:</p> <pre class="code"> primaryIndex.delete(1); // Deletes a single employee by unique ID</pre> <p>But in a secondary index, multiple entities may be deleted:</p> <pre class="code"> secondaryIndex.delete("Engineering"); // Deletes all Engineering employees</pre> <p>This begs this question: How can a single entity be deleted without knowing its primary key? The answer is to use cursors. After locating an entity using a cursor, the entity can be deleted by calling <A HREF="../../../com/sleepycat/persist/EntityCursor.html#delete()"><CODE>EntityCursor.delete()</CODE></A>.</p> <h3>Transactions</h3> <p>Transactions can be used to provide standard ACID (Atomicity, Consistency, Integrity and Durability) guarantees when retrieving, storing and deleting entities. This section provides a brief overview of how to use transactions with the Direct Persistence Layer. For more information on using transactions, see <a href="../../../../gsg_txn/JAVA/index.html">Writing Transactional Applications</a>.</p> <p>Transactions may be used only with a transactional <A HREF="../../../com/sleepycat/persist/EntityStore.html" title="class in com.sleepycat.persist"><CODE>EntityStore</CODE></A>, which is one for which <A HREF="../../../com/sleepycat/persist/StoreConfig.html#setTransactional(boolean)"><CODE>StoreConfig.setTransactional(true)</CODE></A> has been called. Likewise, a transactional store may only be used with a transactional <A HREF="../../../com/sleepycat/db/Environment.html" title="class in com.sleepycat.db"><CODE>Environment</CODE></A>, which is one for which <A HREF="../../../com/sleepycat/db/EnvironmentConfig.html#setTransactional(boolean)"><CODE>EnvironmentConfig.setTransactional(true)</CODE></A> has been called. For example:</p> <pre class="code"> EnvironmentConfig envConfig = new EnvironmentConfig(); envConfig.setTransactional(true); envConfig.setAllowCreate(true); Environment env = new Environment(new File("/my/data"), envConfig); StoreConfig storeConfig = new StoreConfig(); storeConfig.setTransactional(true); storeConfig.setAllowCreate(true); EntityStore store = new EntityStore(env, "myStore", storeConfig);</pre> <p>Transactions are represented by <A HREF="../../../com/sleepycat/db/Transaction.html" title="class in com.sleepycat.db"><CODE>Transaction</CODE></A> objects, which are part of the <CODE>Base API</CODE>. Transactions are created using the <A HREF="../../../com/sleepycat/db/Environment.html#beginTransaction(com.sleepycat.db.Transaction, com.sleepycat.db.TransactionConfig)"><CODE>Environment.beginTransaction</CODE></A> method.</p> <p>A transaction will include all operations for which the transaction object is passed as a method argument. All retrieval, storage and deletion methods have an optional <A HREF="../../../com/sleepycat/db/Transaction.html" title="class in com.sleepycat.db"><CODE>Transaction</CODE></A> parameter for this purpose. When a transaction is passed to a method that opens a cursor, all retrieval, storage and deletion operations performed using that cursor will be included in the transaction.</p> <p>A transaction may be committed by calling <A HREF="../../../com/sleepycat/db/Transaction.html#commit()"><CODE>Transaction.commit()</CODE></A> or aborted by calling <A HREF="../../../com/sleepycat/db/Transaction.html#abort()"><CODE>Transaction.abort()</CODE></A>. For example, two employees may be deleted atomically with a transaction; other words, either both are deleted or neither is deleted:</p> <pre class="code"> Transaction txn = env.beginTransaction(null, null); try { primaryIndex.delete(txn, 1); primaryIndex.delete(txn, 2); txn.commit(); txn = null; } finally { if (txn != null) { txn.abort(); } }</pre> <p><em>WARNING:</em> Transactions must always be committed or aborted to prevent resource leaks which could lead to the index becoming unusable or cause an <code>OutOfMemoryError</code>. To ensure that a transaction is aborted in the face of exceptions, call <A HREF="../../../com/sleepycat/db/Transaction.html#abort()"><CODE>Transaction.abort()</CODE></A> in a finally block.</p> <p>For a transactional store, storage and deletion operations are always transaction protected, whether or not a transaction is explicitly used. A null transaction argument means to perform the operation using auto-commit, or the implied thread transaction if an XAEnvironment is being used. A transaction is automatically started as part of the operation and is automatically committed if the operation completes successfully. The transaction is automatically aborted if an exception occurs during the operation, and the exception is re-thrown to the caller. For example, each employee is deleted using a an auto-commit transaction below, but it is possible that employee 1 will be deleted and employee 2 will not be deleted, if an error or crash occurs while deleting employee 2:</p> <pre class="code"> primaryIndex.delete(null, 1); primaryIndex.delete(null, 2);</pre> <p>When retrieving entities, a null transaction argument means to perform the operation non-transactionally. The operation is performed outside the scope of any transaction, without providing transactional ACID guarantees. If an implied thread transaction is present (i.e. if an XAEnvironment is being used), that transaction is used. When a non-transactional store is used, transactional ACID guarantees are also not provided.</p> <p>For non-transactional and auto-commit usage, overloaded signatures for retrieval, storage and deletion methods are provided to avoid having to pass a null transaction argument. For example, <A HREF="../../../com/sleepycat/persist/EntityIndex.html#delete(K)"><CODE>delete(K)</CODE></A> may be called instead of <A HREF="../../../com/sleepycat/persist/EntityIndex.html#delete(com.sleepycat.db.Transaction, K)"><CODE>delete(Transaction,Object)</CODE></A>. For example, the following code is equivalent to the code above where null was passed for the transaction:</p> <pre class="code"> primaryIndex.delete(1); primaryIndex.delete(2);</pre> <p>For retrieval methods the overloaded signatures also include an optional <A HREF="../../../com/sleepycat/db/LockMode.html" title="class in com.sleepycat.db"><CODE>LockMode</CODE></A> parameter, and overloaded signatures for opening cursors include an optional <A HREF="../../../com/sleepycat/db/CursorConfig.html" title="class in com.sleepycat.db"><CODE>CursorConfig</CODE></A> parameter. These parameters are described further below in the Locking and Lock Modes section.</p> <h3>Transactions and Cursors</h3> <p>There are two special consideration when using cursors with transactions. First, for a transactional store, a non-null transaction must be passed to methods that open a cursor if that cursor will be used to delete or update entities. Cursors do not perform auto-commit when a null transaction is explicitly passed or implied by the method signature. For example, the following code will throw <A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db"><CODE>DatabaseException</CODE></A> when the <A HREF="../../../com/sleepycat/persist/EntityCursor.html#delete()"><CODE>EntityCursor.delete()</CODE></A> method is called:</p> <pre class="code"> // <strong>Does not work with a transactional store!</strong> <code>EntityCursor<Employee></code> cursor = primaryIndex.entities(); try { for (Employee entity : cursor) { cursor.delete(); // <strong>Will throw DatabaseException.</strong> } } finally { cursor.close(); }</pre> <p>Instead, the <A HREF="../../../com/sleepycat/persist/EntityIndex.html#entities(com.sleepycat.db.Transaction, com.sleepycat.db.CursorConfig)"><CODE>entities(Transaction,CursorConfig)</CODE></A> signature must be used and a non-null transaction must be passed:</p> <pre class="code"> <code>EntityCursor<Employee></code> cursor = primaryIndex.entities(txn, null); try { for (Employee entity : cursor) { cursor.delete(); } } finally { cursor.close(); }</pre> <p>The second consideration is that error handling is more complex when using both transactions and cursors, for the following reasons:</p> <ol> <li>When an exception occurs, the transaction should be aborted.</li> <li>Cursors must be closed whether or not an exception occurs.</li> <li>Cursors must be closed before committing or aborting the transaction.</li> </ol> <p>For example:</p> <pre class="code"> Transaction txn = env.beginTransaction(null, null); <code>EntityCursor<Employee></code> cursor = null; try { cursor = primaryIndex.entities(txn, null); for (Employee entity : cursor) { cursor.delete(); } cursor.close(); cursor = null; txn.commit(); txn = null; } finally { if (cursor != null) { cursor.close(); } if (txn != null) { txn.abort(); } }</pre> <h3>Locking and Lock Modes</h3> <p>This section provides a brief overview of locking and describes how lock modes are used with the Direct Persistence Layer. For more information on locking, see <a href="../../../../gsg_txn/JAVA/index.html">Writing Transactional Applications</a>.</p> <p>When using transactions, locks are normally acquired on each entity that is retrieved or stored. The locks are used to isolate one transaction from another. Locks are normally released only when the transaction is committed or aborted.</p> <p>When not using transactions, locks are also normally acquired on each entity that is retrieved or stored. However, these locks are released when the operation is complete. When using cursors, in order to provide <em>cursor stability</em> locks are held until the cursor is moved to a different entity or closed.</p> <p>This default locking behavior provides full transactional ACID guarantees and cursor stability. However, application performance can sometimes be improved by compromising these guarantees. As described in <a href="../../../../gsg_txn/JAVA/index.html">Writing Transactional Applications</a>, the <A HREF="../../../com/sleepycat/db/LockMode.html" title="class in com.sleepycat.db"><CODE>LockMode</CODE></A> and <A HREF="../../../com/sleepycat/db/CursorConfig.html" title="class in com.sleepycat.db"><CODE>CursorConfig</CODE></A> parameters are two of the mechanisms that can be used to make compromises.</p> <p>For example, imagine that you need an approximate count of all entities matching certain criterion, and it is acceptable for entities to be changed by other threads or other transactions while performing this query. <A HREF="../../../com/sleepycat/db/LockMode.html#READ_UNCOMMITTED"><CODE>LockMode.READ_UNCOMMITTED</CODE></A> can be used to perform the retrievals without acquiring any locks. This reduces memory consumption, does less processing, and can improve concurrency.</p> <pre class="code"> <code>EntityCursor<Employee></code> cursor = primaryIndex.entities(txn, null); try { Employee entity; while ((entity = cursor.next(LockMode.READ_UNCOMMITTED)) != null) { // Examine the entity and accumulate totals... } } finally { cursor.close(); }</pre> <p>The <A HREF="../../../com/sleepycat/db/LockMode.html" title="class in com.sleepycat.db"><CODE>LockMode</CODE></A> parameter specifies locking behavior on a per-operation basis. If null or <A HREF="../../../com/sleepycat/db/LockMode.html#DEFAULT"><CODE>LockMode.DEFAULT</CODE></A> is specified, the default lock mode is used.</p> <p>It is also possible to specify the default locking behavior for a cursor using <A HREF="../../../com/sleepycat/db/CursorConfig.html" title="class in com.sleepycat.db"><CODE>CursorConfig</CODE></A>. The example below is equivalent to the example above:</p> <pre class="code"> CursorConfig config = new CursorConfig(); config.setReadUncommitted(true); <code>EntityCursor<Employee></code> cursor = primaryIndex.entities(txn, config); try { Employee entity; while ((entity = cursor.next()) != null) { // Examine the entity and accumulate totals... } } finally { cursor.close(); }</pre> <p>The use of other lock modes, cursor configuration, and transaction configuration are discussed in <a href="../../../../gsg_txn/JAVA/index.html">Writing Transactional Applications</a>.</p> <p>Deadlock handling is another important topic discussed in <a href="../../../../gsg_txn/JAVA/index.html">Writing Transactional Applications</a>. To go along with that material, here we show a deadlock handling loop in the context of the Direct Persistence Layer. The example below shows deleting all entities in a primary index in a single transaction. If a deadlock occurs, the transaction is aborted and the operation is retried.</p> <pre class="code"> int retryCount = 0; boolean retry = true; while (retry) { Transaction txn = env.beginTransaction(null, null); <code>EntityCursor<Employee></code> cursor = null; try { cursor = primaryIndex.entities(txn, null); for (Employee entity : cursor) { cursor.delete(); } cursor.close(); cursor = null; txn.commit(); txn = null; retry = false; } catch (DeadlockException e) { retryCount += 1; if (retryCount >= MAX_DEADLOCK_RETRIES) { throw e; } } finally { if (cursor != null) { cursor.close(); } if (txn != null) { txn.abort(); } } }</pre> <h3>Low Level Access</h3> <p>Each Direct Persistence Layer index is associated with an underlying <A HREF="../../../com/sleepycat/db/Database.html" title="class in com.sleepycat.db"><CODE>Database</CODE></A> or <A HREF="../../../com/sleepycat/db/SecondaryDatabase.html" title="class in com.sleepycat.db"><CODE>SecondaryDatabase</CODE></A> defined in the <CODE>Base API</CODE>. At this level, an index is a Btree managed by the Berkeley DB Java Edition transactional storage engine. Although you may never need to work at the <code>Base API</code> level, keep in mind that some types of performance tuning can be done by configuring the underlying databases. See the <A HREF="../../../com/sleepycat/persist/EntityStore.html" title="class in com.sleepycat.persist"><CODE>EntityStore</CODE></A> class for more information on database and sequence configuration.</p> <p>If you wish to access an index using the <code>Base API</code>, you may call the <A HREF="../../../com/sleepycat/persist/PrimaryIndex.html#getDatabase()"><CODE>PrimaryIndex.getDatabase()</CODE></A> or <A HREF="../../../com/sleepycat/persist/SecondaryIndex.html#getDatabase()"><CODE>SecondaryIndex.getDatabase()</CODE></A> method to get the underlying database. To translate between entity or key objects and <A HREF="../../../com/sleepycat/db/DatabaseEntry.html" title="class in com.sleepycat.db"><CODE>DatabaseEntry</CODE></A> objects at this level, use the bindings returned by <A HREF="../../../com/sleepycat/persist/PrimaryIndex.html#getEntityBinding()"><CODE>PrimaryIndex.getEntityBinding()</CODE></A>, <A HREF="../../../com/sleepycat/persist/PrimaryIndex.html#getKeyBinding()"><CODE>PrimaryIndex.getKeyBinding()</CODE></A>, and <A HREF="../../../com/sleepycat/persist/SecondaryIndex.html#getKeyBinding()"><CODE>SecondaryIndex.getKeyBinding()</CODE></A>.</p> <P> <P> <HR> <P> <!-- ========== METHOD SUMMARY =========== --> <A NAME="method_summary"><!-- --></A> <TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""> <TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"> <TH ALIGN="left" COLSPAN="2"><FONT SIZE="+2"> <B>Method Summary</B></FONT></TH> </TR> <TR BGCOLOR="white" CLASS="TableRowColor"> <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> <CODE> boolean</CODE></FONT></TD> <TD><CODE><B><A HREF="../../../com/sleepycat/persist/EntityIndex.html#contains(K)">contains</A></B>(<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> key)</CODE> <BR> Checks for existence of a key in this index.</TD> </TR> <TR BGCOLOR="white" CLASS="TableRowColor"> <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> <CODE> boolean</CODE></FONT></TD> <TD><CODE><B><A HREF="../../../com/sleepycat/persist/EntityIndex.html#contains(com.sleepycat.db.Transaction, K, com.sleepycat.db.LockMode)">contains</A></B>(<A HREF="../../../com/sleepycat/db/Transaction.html" title="class in com.sleepycat.db">Transaction</A> txn, <A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> key, <A HREF="../../../com/sleepycat/db/LockMode.html" title="class in com.sleepycat.db">LockMode</A> lockMode)</CODE> <BR> Checks for existence of a key in this index.</TD> </TR> <TR BGCOLOR="white" CLASS="TableRowColor"> <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> <CODE> long</CODE></FONT></TD> <TD><CODE><B><A HREF="../../../com/sleepycat/persist/EntityIndex.html#count()">count</A></B>()</CODE> <BR> Returns a non-transactional count of the entities in this index.</TD> </TR> <TR BGCOLOR="white" CLASS="TableRowColor"> <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> <CODE> boolean</CODE></FONT></TD> <TD><CODE><B><A HREF="../../../com/sleepycat/persist/EntityIndex.html#delete(K)">delete</A></B>(<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> key)</CODE> <BR> Deletes all entities with a given index key.</TD> </TR> <TR BGCOLOR="white" CLASS="TableRowColor"> <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> <CODE> boolean</CODE></FONT></TD> <TD><CODE><B><A HREF="../../../com/sleepycat/persist/EntityIndex.html#delete(com.sleepycat.db.Transaction, K)">delete</A></B>(<A HREF="../../../com/sleepycat/db/Transaction.html" title="class in com.sleepycat.db">Transaction</A> txn, <A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> key)</CODE> <BR> Deletes all entities with a given index key.</TD> </TR> <TR BGCOLOR="white" CLASS="TableRowColor"> <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> <CODE> <A HREF="../../../com/sleepycat/persist/EntityCursor.html" title="interface in com.sleepycat.persist">EntityCursor</A><<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">V</A>></CODE></FONT></TD> <TD><CODE><B><A HREF="../../../com/sleepycat/persist/EntityIndex.html#entities()">entities</A></B>()</CODE> <BR> Opens a cursor for traversing all entities in this index.</TD> </TR> <TR BGCOLOR="white" CLASS="TableRowColor"> <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> <CODE> <A HREF="../../../com/sleepycat/persist/EntityCursor.html" title="interface in com.sleepycat.persist">EntityCursor</A><<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">V</A>></CODE></FONT></TD> <TD><CODE><B><A HREF="../../../com/sleepycat/persist/EntityIndex.html#entities(K, boolean, K, boolean)">entities</A></B>(<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> fromKey, boolean fromInclusive, <A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> toKey, boolean toInclusive)</CODE> <BR> Opens a cursor for traversing entities in a key range.</TD> </TR> <TR BGCOLOR="white" CLASS="TableRowColor"> <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> <CODE> <A HREF="../../../com/sleepycat/persist/EntityCursor.html" title="interface in com.sleepycat.persist">EntityCursor</A><<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">V</A>></CODE></FONT></TD> <TD><CODE><B><A HREF="../../../com/sleepycat/persist/EntityIndex.html#entities(com.sleepycat.db.Transaction, com.sleepycat.db.CursorConfig)">entities</A></B>(<A HREF="../../../com/sleepycat/db/Transaction.html" title="class in com.sleepycat.db">Transaction</A> txn, <A HREF="../../../com/sleepycat/db/CursorConfig.html" title="class in com.sleepycat.db">CursorConfig</A> config)</CODE> <BR> Opens a cursor for traversing all entities in this index.</TD> </TR> <TR BGCOLOR="white" CLASS="TableRowColor"> <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> <CODE> <A HREF="../../../com/sleepycat/persist/EntityCursor.html" title="interface in com.sleepycat.persist">EntityCursor</A><<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">V</A>></CODE></FONT></TD> <TD><CODE><B><A HREF="../../../com/sleepycat/persist/EntityIndex.html#entities(com.sleepycat.db.Transaction, K, boolean, K, boolean, com.sleepycat.db.CursorConfig)">entities</A></B>(<A HREF="../../../com/sleepycat/db/Transaction.html" title="class in com.sleepycat.db">Transaction</A> txn, <A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> fromKey, boolean fromInclusive, <A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> toKey, boolean toInclusive, <A HREF="../../../com/sleepycat/db/CursorConfig.html" title="class in com.sleepycat.db">CursorConfig</A> config)</CODE> <BR> Opens a cursor for traversing entities in a key range.</TD> </TR> <TR BGCOLOR="white" CLASS="TableRowColor"> <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> <CODE> <A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">V</A></CODE></FONT></TD> <TD><CODE><B><A HREF="../../../com/sleepycat/persist/EntityIndex.html#get(K)">get</A></B>(<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> key)</CODE> <BR> Gets an entity via a key of this index.</TD> </TR> <TR BGCOLOR="white" CLASS="TableRowColor"> <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> <CODE> <A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">V</A></CODE></FONT></TD> <TD><CODE><B><A HREF="../../../com/sleepycat/persist/EntityIndex.html#get(com.sleepycat.db.Transaction, K, com.sleepycat.db.LockMode)">get</A></B>(<A HREF="../../../com/sleepycat/db/Transaction.html" title="class in com.sleepycat.db">Transaction</A> txn, <A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> key, <A HREF="../../../com/sleepycat/db/LockMode.html" title="class in com.sleepycat.db">LockMode</A> lockMode)</CODE> <BR> Gets an entity via a key of this index.</TD> </TR> <TR BGCOLOR="white" CLASS="TableRowColor"> <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> <CODE> <A HREF="../../../com/sleepycat/persist/EntityCursor.html" title="interface in com.sleepycat.persist">EntityCursor</A><<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A>></CODE></FONT></TD> <TD><CODE><B><A HREF="../../../com/sleepycat/persist/EntityIndex.html#keys()">keys</A></B>()</CODE> <BR> Opens a cursor for traversing all keys in this index.</TD> </TR> <TR BGCOLOR="white" CLASS="TableRowColor"> <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> <CODE> <A HREF="../../../com/sleepycat/persist/EntityCursor.html" title="interface in com.sleepycat.persist">EntityCursor</A><<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A>></CODE></FONT></TD> <TD><CODE><B><A HREF="../../../com/sleepycat/persist/EntityIndex.html#keys(K, boolean, K, boolean)">keys</A></B>(<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> fromKey, boolean fromInclusive, <A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> toKey, boolean toInclusive)</CODE> <BR> Opens a cursor for traversing keys in a key range.</TD> </TR> <TR BGCOLOR="white" CLASS="TableRowColor"> <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> <CODE> <A HREF="../../../com/sleepycat/persist/EntityCursor.html" title="interface in com.sleepycat.persist">EntityCursor</A><<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A>></CODE></FONT></TD> <TD><CODE><B><A HREF="../../../com/sleepycat/persist/EntityIndex.html#keys(com.sleepycat.db.Transaction, com.sleepycat.db.CursorConfig)">keys</A></B>(<A HREF="../../../com/sleepycat/db/Transaction.html" title="class in com.sleepycat.db">Transaction</A> txn, <A HREF="../../../com/sleepycat/db/CursorConfig.html" title="class in com.sleepycat.db">CursorConfig</A> config)</CODE> <BR> Opens a cursor for traversing all keys in this index.</TD> </TR> <TR BGCOLOR="white" CLASS="TableRowColor"> <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> <CODE> <A HREF="../../../com/sleepycat/persist/EntityCursor.html" title="interface in com.sleepycat.persist">EntityCursor</A><<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A>></CODE></FONT></TD> <TD><CODE><B><A HREF="../../../com/sleepycat/persist/EntityIndex.html#keys(com.sleepycat.db.Transaction, K, boolean, K, boolean, com.sleepycat.db.CursorConfig)">keys</A></B>(<A HREF="../../../com/sleepycat/db/Transaction.html" title="class in com.sleepycat.db">Transaction</A> txn, <A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> fromKey, boolean fromInclusive, <A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> toKey, boolean toInclusive, <A HREF="../../../com/sleepycat/db/CursorConfig.html" title="class in com.sleepycat.db">CursorConfig</A> config)</CODE> <BR> Opens a cursor for traversing keys in a key range.</TD> </TR> <TR BGCOLOR="white" CLASS="TableRowColor"> <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> <CODE> java.util.Map<<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A>,<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">V</A>></CODE></FONT></TD> <TD><CODE><B><A HREF="../../../com/sleepycat/persist/EntityIndex.html#map()">map</A></B>()</CODE> <BR> Returns a standard Java map based on this entity index.</TD> </TR> <TR BGCOLOR="white" CLASS="TableRowColor"> <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> <CODE> java.util.SortedMap<<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A>,<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">V</A>></CODE></FONT></TD> <TD><CODE><B><A HREF="../../../com/sleepycat/persist/EntityIndex.html#sortedMap()">sortedMap</A></B>()</CODE> <BR> Returns a standard Java sorted map based on this entity index.</TD> </TR> </TABLE> <P> <!-- ============ METHOD DETAIL ========== --> <A NAME="method_detail"><!-- --></A> <TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""> <TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"> <TH ALIGN="left" COLSPAN="1"><FONT SIZE="+2"> <B>Method Detail</B></FONT></TH> </TR> </TABLE> <A NAME="contains(java.lang.Object)"><!-- --></A><A NAME="contains(K)"><!-- --></A><H3> contains</H3> <PRE> boolean <B>contains</B>(<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> key) throws <A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></PRE> <DL> <DD>Checks for existence of a key in this index. <p>The operation will not be transaction protected, and <A HREF="../../../com/sleepycat/db/LockMode.html#DEFAULT"><CODE>LockMode.DEFAULT</CODE></A> is used implicitly.</p> <P> <DD><DL> <DT><B>Parameters:</B><DD><CODE>key</CODE> - the key to search for. <DT><B>Returns:</B><DD>whether the key exists in the index. <DT><B>Throws:</B> <DD><CODE><A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></CODE></DL> </DD> </DL> <HR> <A NAME="contains(com.sleepycat.db.Transaction,java.lang.Object,com.sleepycat.db.LockMode)"><!-- --></A><A NAME="contains(com.sleepycat.db.Transaction, K, com.sleepycat.db.LockMode)"><!-- --></A><H3> contains</H3> <PRE> boolean <B>contains</B>(<A HREF="../../../com/sleepycat/db/Transaction.html" title="class in com.sleepycat.db">Transaction</A> txn, <A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> key, <A HREF="../../../com/sleepycat/db/LockMode.html" title="class in com.sleepycat.db">LockMode</A> lockMode) throws <A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></PRE> <DL> <DD>Checks for existence of a key in this index. <P> <DD><DL> <DT><B>Parameters:</B><DD><CODE>txn</CODE> - the transaction used to protect this operation, or null if the operation should not be transaction protected.<DD><CODE>key</CODE> - the key to search for.<DD><CODE>lockMode</CODE> - the lock mode to use for this operation, or null to use <A HREF="../../../com/sleepycat/db/LockMode.html#DEFAULT"><CODE>LockMode.DEFAULT</CODE></A>. <DT><B>Returns:</B><DD>whether the key exists in the index. <DT><B>Throws:</B> <DD><CODE><A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></CODE></DL> </DD> </DL> <HR> <A NAME="get(java.lang.Object)"><!-- --></A><A NAME="get(K)"><!-- --></A><H3> get</H3> <PRE> <A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">V</A> <B>get</B>(<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> key) throws <A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></PRE> <DL> <DD>Gets an entity via a key of this index. <p>The operation will not be transaction protected, and <A HREF="../../../com/sleepycat/db/LockMode.html#DEFAULT"><CODE>LockMode.DEFAULT</CODE></A> is used implicitly.</p> <P> <DD><DL> <DT><B>Parameters:</B><DD><CODE>key</CODE> - the key to search for. <DT><B>Returns:</B><DD>the value mapped to the given key, or null if the key is not present in the index. <DT><B>Throws:</B> <DD><CODE><A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></CODE></DL> </DD> </DL> <HR> <A NAME="get(com.sleepycat.db.Transaction,java.lang.Object,com.sleepycat.db.LockMode)"><!-- --></A><A NAME="get(com.sleepycat.db.Transaction, K, com.sleepycat.db.LockMode)"><!-- --></A><H3> get</H3> <PRE> <A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">V</A> <B>get</B>(<A HREF="../../../com/sleepycat/db/Transaction.html" title="class in com.sleepycat.db">Transaction</A> txn, <A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> key, <A HREF="../../../com/sleepycat/db/LockMode.html" title="class in com.sleepycat.db">LockMode</A> lockMode) throws <A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></PRE> <DL> <DD>Gets an entity via a key of this index. <P> <DD><DL> <DT><B>Parameters:</B><DD><CODE>txn</CODE> - the transaction used to protect this operation, or null if the operation should not be transaction protected.<DD><CODE>key</CODE> - the key to search for.<DD><CODE>lockMode</CODE> - the lock mode to use for this operation, or null to use <A HREF="../../../com/sleepycat/db/LockMode.html#DEFAULT"><CODE>LockMode.DEFAULT</CODE></A>. <DT><B>Returns:</B><DD>the value mapped to the given key, or null if the key is not present in the index. <DT><B>Throws:</B> <DD><CODE><A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></CODE></DL> </DD> </DL> <HR> <A NAME="count()"><!-- --></A><H3> count</H3> <PRE> long <B>count</B>() throws <A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></PRE> <DL> <DD>Returns a non-transactional count of the entities in this index. <p>This operation is faster than obtaining a count by scanning the index manually, and will not perturb the current contents of the cache. However, the count is not guaranteed to be accurate if there are concurrent updates.</p> <P> <DD><DL> <DT><B>Returns:</B><DD>the number of entities in this index. <DT><B>Throws:</B> <DD><CODE><A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></CODE></DL> </DD> </DL> <HR> <A NAME="delete(java.lang.Object)"><!-- --></A><A NAME="delete(K)"><!-- --></A><H3> delete</H3> <PRE> boolean <B>delete</B>(<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> key) throws <A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></PRE> <DL> <DD>Deletes all entities with a given index key. <p>Auto-commit is used implicitly if the store is transactional.</p> <P> <DD><DL> <DT><B>Parameters:</B><DD><CODE>key</CODE> - the key to search for. <DT><B>Returns:</B><DD>whether any entities were deleted. <DT><B>Throws:</B> <DD><CODE><A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></CODE></DL> </DD> </DL> <HR> <A NAME="delete(com.sleepycat.db.Transaction,java.lang.Object)"><!-- --></A><A NAME="delete(com.sleepycat.db.Transaction, K)"><!-- --></A><H3> delete</H3> <PRE> boolean <B>delete</B>(<A HREF="../../../com/sleepycat/db/Transaction.html" title="class in com.sleepycat.db">Transaction</A> txn, <A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> key) throws <A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></PRE> <DL> <DD>Deletes all entities with a given index key. <P> <DD><DL> <DT><B>Parameters:</B><DD><CODE>txn</CODE> - the transaction used to protect this operation, null to use auto-commit, or null if the store is non-transactional.<DD><CODE>key</CODE> - the key to search for. <DT><B>Returns:</B><DD>whether any entities were deleted. <DT><B>Throws:</B> <DD><CODE><A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></CODE></DL> </DD> </DL> <HR> <A NAME="keys()"><!-- --></A><H3> keys</H3> <PRE> <A HREF="../../../com/sleepycat/persist/EntityCursor.html" title="interface in com.sleepycat.persist">EntityCursor</A><<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A>> <B>keys</B>() throws <A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></PRE> <DL> <DD>Opens a cursor for traversing all keys in this index. <p>The operations performed with the cursor will not be transaction protected, and <A HREF="../../../com/sleepycat/db/CursorConfig.html#DEFAULT"><CODE>CursorConfig.DEFAULT</CODE></A> is used implicitly. If the store is transactional, the cursor may not be used to update or delete entities.</p> <P> <DD><DL> <DT><B>Returns:</B><DD>the cursor. <DT><B>Throws:</B> <DD><CODE><A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></CODE></DL> </DD> </DL> <HR> <A NAME="keys(com.sleepycat.db.Transaction, com.sleepycat.db.CursorConfig)"><!-- --></A><H3> keys</H3> <PRE> <A HREF="../../../com/sleepycat/persist/EntityCursor.html" title="interface in com.sleepycat.persist">EntityCursor</A><<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A>> <B>keys</B>(<A HREF="../../../com/sleepycat/db/Transaction.html" title="class in com.sleepycat.db">Transaction</A> txn, <A HREF="../../../com/sleepycat/db/CursorConfig.html" title="class in com.sleepycat.db">CursorConfig</A> config) throws <A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></PRE> <DL> <DD>Opens a cursor for traversing all keys in this index. <P> <DD><DL> <DT><B>Parameters:</B><DD><CODE>txn</CODE> - the transaction used to protect all operations performed with the cursor, or null if the operations should not be transaction protected. If null is specified and the store is transactional, the cursor may not be used to update or delete entities.<DD><CODE>config</CODE> - the cursor configuration that determines the default lock mode used for all cursor operations, or null to implicitly use <A HREF="../../../com/sleepycat/db/CursorConfig.html#DEFAULT"><CODE>CursorConfig.DEFAULT</CODE></A>. <DT><B>Returns:</B><DD>the cursor. <DT><B>Throws:</B> <DD><CODE><A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></CODE></DL> </DD> </DL> <HR> <A NAME="entities()"><!-- --></A><H3> entities</H3> <PRE> <A HREF="../../../com/sleepycat/persist/EntityCursor.html" title="interface in com.sleepycat.persist">EntityCursor</A><<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">V</A>> <B>entities</B>() throws <A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></PRE> <DL> <DD>Opens a cursor for traversing all entities in this index. <p>The operations performed with the cursor will not be transaction protected, and <A HREF="../../../com/sleepycat/db/CursorConfig.html#DEFAULT"><CODE>CursorConfig.DEFAULT</CODE></A> is used implicitly. If the store is transactional, the cursor may not be used to update or delete entities.</p> <P> <DD><DL> <DT><B>Returns:</B><DD>the cursor. <DT><B>Throws:</B> <DD><CODE><A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></CODE></DL> </DD> </DL> <HR> <A NAME="entities(com.sleepycat.db.Transaction, com.sleepycat.db.CursorConfig)"><!-- --></A><H3> entities</H3> <PRE> <A HREF="../../../com/sleepycat/persist/EntityCursor.html" title="interface in com.sleepycat.persist">EntityCursor</A><<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">V</A>> <B>entities</B>(<A HREF="../../../com/sleepycat/db/Transaction.html" title="class in com.sleepycat.db">Transaction</A> txn, <A HREF="../../../com/sleepycat/db/CursorConfig.html" title="class in com.sleepycat.db">CursorConfig</A> config) throws <A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></PRE> <DL> <DD>Opens a cursor for traversing all entities in this index. <P> <DD><DL> <DT><B>Parameters:</B><DD><CODE>txn</CODE> - the transaction used to protect all operations performed with the cursor, or null if the operations should not be transaction protected. If null is specified and the store is transactional, the cursor may not be used to update or delete entities.<DD><CODE>config</CODE> - the cursor configuration that determines the default lock mode used for all cursor operations, or null to implicitly use <A HREF="../../../com/sleepycat/db/CursorConfig.html#DEFAULT"><CODE>CursorConfig.DEFAULT</CODE></A>. <DT><B>Returns:</B><DD>the cursor. <DT><B>Throws:</B> <DD><CODE><A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></CODE></DL> </DD> </DL> <HR> <A NAME="keys(java.lang.Object,boolean,java.lang.Object,boolean)"><!-- --></A><A NAME="keys(K, boolean, K, boolean)"><!-- --></A><H3> keys</H3> <PRE> <A HREF="../../../com/sleepycat/persist/EntityCursor.html" title="interface in com.sleepycat.persist">EntityCursor</A><<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A>> <B>keys</B>(<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> fromKey, boolean fromInclusive, <A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> toKey, boolean toInclusive) throws <A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></PRE> <DL> <DD>Opens a cursor for traversing keys in a key range. <p>The operations performed with the cursor will not be transaction protected, and <A HREF="../../../com/sleepycat/db/CursorConfig.html#DEFAULT"><CODE>CursorConfig.DEFAULT</CODE></A> is used implicitly. If the store is transactional, the cursor may not be used to update or delete entities.</p> <P> <DD><DL> <DT><B>Parameters:</B><DD><CODE>fromKey</CODE> - is the lower bound of the key range, or null if the range has no lower bound.<DD><CODE>fromInclusive</CODE> - is true if keys greater than or equal to fromKey should be included in the key range, or false if only keys greater than fromKey should be included.<DD><CODE>toKey</CODE> - is the upper bound of the key range, or null if the range has no upper bound.<DD><CODE>toInclusive</CODE> - is true if keys less than or equal to toKey should be included in the key range, or false if only keys less than toKey should be included. <DT><B>Returns:</B><DD>the cursor. <DT><B>Throws:</B> <DD><CODE><A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></CODE></DL> </DD> </DL> <HR> <A NAME="keys(com.sleepycat.db.Transaction,java.lang.Object,boolean,java.lang.Object,boolean,com.sleepycat.db.CursorConfig)"><!-- --></A><A NAME="keys(com.sleepycat.db.Transaction, K, boolean, K, boolean, com.sleepycat.db.CursorConfig)"><!-- --></A><H3> keys</H3> <PRE> <A HREF="../../../com/sleepycat/persist/EntityCursor.html" title="interface in com.sleepycat.persist">EntityCursor</A><<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A>> <B>keys</B>(<A HREF="../../../com/sleepycat/db/Transaction.html" title="class in com.sleepycat.db">Transaction</A> txn, <A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> fromKey, boolean fromInclusive, <A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> toKey, boolean toInclusive, <A HREF="../../../com/sleepycat/db/CursorConfig.html" title="class in com.sleepycat.db">CursorConfig</A> config) throws <A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></PRE> <DL> <DD>Opens a cursor for traversing keys in a key range. <P> <DD><DL> <DT><B>Parameters:</B><DD><CODE>txn</CODE> - the transaction used to protect all operations performed with the cursor, or null if the operations should not be transaction protected. If null is specified and the store is transactional, the cursor may not be used to update or delete entities.<DD><CODE>fromKey</CODE> - is the lower bound of the key range, or null if the range has no lower bound.<DD><CODE>fromInclusive</CODE> - is true if keys greater than or equal to fromKey should be included in the key range, or false if only keys greater than fromKey should be included.<DD><CODE>toKey</CODE> - is the upper bound of the key range, or null if the range has no upper bound.<DD><CODE>toInclusive</CODE> - is true if keys less than or equal to toKey should be included in the key range, or false if only keys less than toKey should be included.<DD><CODE>config</CODE> - the cursor configuration that determines the default lock mode used for all cursor operations, or null to implicitly use <A HREF="../../../com/sleepycat/db/CursorConfig.html#DEFAULT"><CODE>CursorConfig.DEFAULT</CODE></A>. <DT><B>Returns:</B><DD>the cursor. <DT><B>Throws:</B> <DD><CODE><A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></CODE></DL> </DD> </DL> <HR> <A NAME="entities(java.lang.Object,boolean,java.lang.Object,boolean)"><!-- --></A><A NAME="entities(K, boolean, K, boolean)"><!-- --></A><H3> entities</H3> <PRE> <A HREF="../../../com/sleepycat/persist/EntityCursor.html" title="interface in com.sleepycat.persist">EntityCursor</A><<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">V</A>> <B>entities</B>(<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> fromKey, boolean fromInclusive, <A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> toKey, boolean toInclusive) throws <A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></PRE> <DL> <DD>Opens a cursor for traversing entities in a key range. <p>The operations performed with the cursor will not be transaction protected, and <A HREF="../../../com/sleepycat/db/CursorConfig.html#DEFAULT"><CODE>CursorConfig.DEFAULT</CODE></A> is used implicitly. If the store is transactional, the cursor may not be used to update or delete entities.</p> <P> <DD><DL> <DT><B>Parameters:</B><DD><CODE>fromKey</CODE> - is the lower bound of the key range, or null if the range has no lower bound.<DD><CODE>fromInclusive</CODE> - is true if keys greater than or equal to fromKey should be included in the key range, or false if only keys greater than fromKey should be included.<DD><CODE>toKey</CODE> - is the upper bound of the key range, or null if the range has no upper bound.<DD><CODE>toInclusive</CODE> - is true if keys less than or equal to toKey should be included in the key range, or false if only keys less than toKey should be included. <DT><B>Returns:</B><DD>the cursor. <DT><B>Throws:</B> <DD><CODE><A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></CODE></DL> </DD> </DL> <HR> <A NAME="entities(com.sleepycat.db.Transaction,java.lang.Object,boolean,java.lang.Object,boolean,com.sleepycat.db.CursorConfig)"><!-- --></A><A NAME="entities(com.sleepycat.db.Transaction, K, boolean, K, boolean, com.sleepycat.db.CursorConfig)"><!-- --></A><H3> entities</H3> <PRE> <A HREF="../../../com/sleepycat/persist/EntityCursor.html" title="interface in com.sleepycat.persist">EntityCursor</A><<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">V</A>> <B>entities</B>(<A HREF="../../../com/sleepycat/db/Transaction.html" title="class in com.sleepycat.db">Transaction</A> txn, <A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> fromKey, boolean fromInclusive, <A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A> toKey, boolean toInclusive, <A HREF="../../../com/sleepycat/db/CursorConfig.html" title="class in com.sleepycat.db">CursorConfig</A> config) throws <A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></PRE> <DL> <DD>Opens a cursor for traversing entities in a key range. <P> <DD><DL> <DT><B>Parameters:</B><DD><CODE>txn</CODE> - the transaction used to protect all operations performed with the cursor, or null if the operations should not be transaction protected. If null is specified and the store is transactional, the cursor may not be used to update or delete entities.<DD><CODE>fromKey</CODE> - is the lower bound of the key range, or null if the range has no lower bound.<DD><CODE>fromInclusive</CODE> - is true if keys greater than or equal to fromKey should be included in the key range, or false if only keys greater than fromKey should be included.<DD><CODE>toKey</CODE> - is the upper bound of the key range, or null if the range has no upper bound.<DD><CODE>toInclusive</CODE> - is true if keys less than or equal to toKey should be included in the key range, or false if only keys less than toKey should be included.<DD><CODE>config</CODE> - the cursor configuration that determines the default lock mode used for all cursor operations, or null to implicitly use <A HREF="../../../com/sleepycat/db/CursorConfig.html#DEFAULT"><CODE>CursorConfig.DEFAULT</CODE></A>. <DT><B>Returns:</B><DD>the cursor. <DT><B>Throws:</B> <DD><CODE><A HREF="../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db">DatabaseException</A></CODE></DL> </DD> </DL> <HR> <A NAME="map()"><!-- --></A><H3> map</H3> <PRE> java.util.Map<<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A>,<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">V</A>> <B>map</B>()</PRE> <DL> <DD>Returns a standard Java map based on this entity index. The <A HREF="../../../com/sleepycat/collections/StoredMap.html" title="class in com.sleepycat.collections"><CODE>StoredMap</CODE></A> returned is defined by the Collections API. Stored collections conform to the standard Java collections framework interface. <P> <DD><DL> <DT><B>Returns:</B><DD>the map.</DL> </DD> </DL> <HR> <A NAME="sortedMap()"><!-- --></A><H3> sortedMap</H3> <PRE> java.util.SortedMap<<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">K</A>,<A HREF="../../../com/sleepycat/persist/EntityIndex.html" title="type parameter in EntityIndex">V</A>> <B>sortedMap</B>()</PRE> <DL> <DD>Returns a standard Java sorted map based on this entity index. The <A HREF="../../../com/sleepycat/collections/StoredSortedMap.html" title="class in com.sleepycat.collections"><CODE>StoredSortedMap</CODE></A> returned is defined by the Collections API. Stored collections conform to the standard Java collections framework interface. <P> <DD><DL> <DT><B>Returns:</B><DD>the map.</DL> </DD> </DL> <!-- ========= END OF CLASS DATA ========= --> <HR> <!-- ======= START OF BOTTOM NAVBAR ====== --> <A NAME="navbar_bottom"><!-- --></A> <A HREF="#skip-navbar_bottom" title="Skip navigation links"></A> <TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0" SUMMARY=""> <TR> <TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A NAME="navbar_bottom_firstrow"><!-- --></A> <TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3" SUMMARY=""> <TR ALIGN="center" VALIGN="top"> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../overview-summary.html"><FONT CLASS="NavBarFont1"><B>Overview</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-summary.html"><FONT CLASS="NavBarFont1"><B>Package</B></FONT></A> </TD> <TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> <FONT CLASS="NavBarFont1Rev"><B>Class</B></FONT> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-tree.html"><FONT CLASS="NavBarFont1"><B>Tree</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../deprecated-list.html"><FONT CLASS="NavBarFont1"><B>Deprecated</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../index-all.html"><FONT CLASS="NavBarFont1"><B>Index</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../help-doc.html"><FONT CLASS="NavBarFont1"><B>Help</B></FONT></A> </TD> </TR> </TABLE> </TD> <TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM> </EM> </TD> </TR> <TR> <TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../../com/sleepycat/persist/EntityCursor.html" title="interface in com.sleepycat.persist"><B>PREV CLASS</B></A> <A HREF="../../../com/sleepycat/persist/EntityJoin.html" title="class in com.sleepycat.persist"><B>NEXT CLASS</B></A></FONT></TD> <TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../../index.html?com/sleepycat/persist/EntityIndex.html" target="_top"><B>FRAMES</B></A> <A HREF="EntityIndex.html" target="_top"><B>NO FRAMES</B></A> <SCRIPT type="text/javascript"> <!-- if(window==top) { document.writeln('<A HREF="../../../allclasses-noframe.html"><B>All Classes</B></A>'); } //--> </SCRIPT> <NOSCRIPT> <A HREF="../../../allclasses-noframe.html"><B>All Classes</B></A> </NOSCRIPT> </FONT></TD> </TR> <TR> <TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> SUMMARY: NESTED | FIELD | CONSTR | <A HREF="#method_summary">METHOD</A></FONT></TD> <TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> DETAIL: FIELD | CONSTR | <A HREF="#method_detail">METHOD</A></FONT></TD> </TR> </TABLE> <A NAME="skip-navbar_bottom"></A> <!-- ======== END OF BOTTOM NAVBAR ======= --> <HR> </BODY> </HTML>