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<th colspan="3" align="center">Opening a Transactional Environment and
<span xmlns="http://www.w3.org/1999/xhtml">Store or Database</span>
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<div class="sect1" lang="en" xml:lang="en">
<div class="titlepage">
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<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>
<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). You must 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 <code class="classname">Environment</code> handle to open
your database(s) using <code class="methodname">Environment.openDatabase()</code>.
Note that when you do this, you must set
<code class="methodname">DatabaseConfig.setTransactional()</code>
to <code class="literal">true</code>. 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;
<strong class="userinput"><code>import com.sleepycat.db.Database;
import com.sleepycat.db.DatabaseType;
import com.sleepycat.db.DatabaseConfig;</code></strong>
import com.sleepycat.db.DatabaseException;
import com.sleepycat.db.Environment;
import com.sleepycat.db.EnvironmentConfig;
import java.io.File;
import java.io.FileNotFoundException;
...
<strong class="userinput"><code>Database myDatabase = null;</code></strong>
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);
<strong class="userinput"><code>// 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);</code></strong>
} 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>
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<td width="40%" align="left" valign="top">Chapter 2. Enabling Transactions </td>
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