<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>Opening a Transactional Environment and Store or Database </title> <link rel="stylesheet" href="gettingStarted.css" type="text/css" /> <meta name="generator" content="DocBook XSL Stylesheets V1.62.4" /> <link rel="home" href="index.html" title="Getting Started with Berkeley DB Transaction Processing" /> <link rel="up" href="enabletxn.html" title="Chapter 2. Enabling Transactions" /> <link rel="previous" href="enabletxn.html" title="Chapter 2. Enabling Transactions" /> <link rel="next" href="usingtxns.html" title="Chapter 3. Transaction Basics" /> </head> <body> <div class="navheader"> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">Opening a Transactional Environment and Store or Database </th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="enabletxn.html">Prev</a> </td> <th width="60%" align="center">Chapter 2. Enabling Transactions</th> <td width="20%" align="right"> <a accesskey="n" href="usingtxns.html">Next</a></td> </tr> </table> <hr /> </div> <div class="sect1" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h2 class="title" style="clear: both"><a id="envopen"></a>Opening a Transactional Environment and <span>Store or Database</span> </h2> </div> </div> <div></div> </div> <p> To enable transactions for your environment, you must initialize the transactional subsystem. Note that doing this also initializes the logging subsystem. In addition, you must initialize the memory pool (in-memory cache). Frequently, but not always, you will also initialize the locking subsystem. <span> For example, to do this with the DPL: </span> </p> <pre class="programlisting">package persist.txn; import com.sleepycat.db.DatabaseException; import com.sleepycat.db.Environment; import com.sleepycat.db.EnvironmentConfig; import com.sleepycat.persist.EntityStore; import com.sleepycat.persist.StoreConfig; import java.io.File; import java.io.FileNotFoundException; ... Environment myEnv = null; EntityStore myStore = null; try { EnvironmentConfig myEnvConfig = new EnvironmentConfig(); StoreConfig storeConfig = new StoreConfig(); myEnvConfig.setInitializeCache(true); myEnvConfig.setInitializeLocking(true); myEnvConfig.setInitializeLogging(true); myEnvConfig.setTransactional(true); storeConfig.setTransactional(true); myEnv = new Environment(new File("/my/env/home"), myEnvConfig); myStore = new EntityStore(myEnv, "EntityStore", storeConfig); } catch (DatabaseException de) { // Exception handling goes here } catch (FileNotFoundException fnfe) { // Exception handling goes here }</pre> <p> And when using the base API: </p> <pre class="programlisting">package db.txn; import com.sleepycat.db.DatabaseException; import com.sleepycat.db.Environment; import com.sleepycat.db.EnvironmentConfig; import java.io.File; import java.io.FileNotFoundException; ... Environment myEnv = null; try { EnvironmentConfig myEnvConfig = new EnvironmentConfig(); myEnvConfig.setInitializeCache(true); myEnvConfig.setInitializeLocking(true); myEnvConfig.setInitializeLogging(true); myEnvConfig.setTransactional(true); myEnv = new Environment(new File("/my/env/home"), myEnvConfig); } catch (DatabaseException de) { // Exception handling goes here } catch (FileNotFoundException fnfe) { // Exception handling goes here }</pre> <p> You then can use the <tt class="classname">Environment</tt> handle to open your database(s) using <tt class="methodname">Environment.openDatabase()</tt>. Note that when you do this, you must set <tt class="methodname">DatabaseConfig.setTransactional()</tt> to <tt class="literal">true</tt>. Note that in effect this causes the database open to be transactional protected because it results in auto commit being used for the open (if a transaction is not explicitly used to protect the open). For example: </p> <pre class="programlisting">package db.txn; <b class="userinput"><tt>import com.sleepycat.db.Database; import com.sleepycat.db.DatabaseType; import com.sleepycat.db.DatabaseConfig;</tt></b> import com.sleepycat.db.DatabaseException; import com.sleepycat.db.Environment; import com.sleepycat.db.EnvironmentConfig; import java.io.File; import java.io.FileNotFoundException; ... <b class="userinput"><tt>Database myDatabase = null;</tt></b> Environment myEnv = null; try { EnvironmentConfig myEnvConfig = new EnvironmentConfig(); myEnvConfig.setInitializeCache(true); myEnvConfig.setInitializeLocking(true); myEnvConfig.setInitializeLogging(true); myEnvConfig.setTransactional(true); myEnv = new Environment(new File("/my/env/home"), myEnvConfig); <b class="userinput"><tt>// Open the database. DatabaseConfig dbConfig = new DatabaseConfig(); dbConfig.setTransactional(true); dbConfig.setType(DatabaseType.BTREE); myDatabase = myEnv.openDatabase(null, // txn handle "sampleDatabase", // db file name null, // db name dbConfig);</tt></b> } catch (DatabaseException de) { // Exception handling goes here } catch (FileNotFoundException fnfe) { // Exception handling goes here }</pre> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <h3 class="title">Note</h3> <p> Never close a database <span> or store </span> that has active transactions. Make sure all transactions are resolved (either committed or aborted) before closing the database. </p> </div> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="enabletxn.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="enabletxn.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="usingtxns.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">Chapter 2. Enabling Transactions </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> Chapter 3. Transaction Basics</td> </tr> </table> </div> </body> </html>