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<h1>22. Virtuoso Functions Guide - checkpoint_interval</h1>
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<div id="text">
<h2>checkpoint_interval</h2>
<div class="refpurpose">Configure database checkpointing</div>
<div class="funcsynopsis">
<span class="funcdef">integer <span class="function">checkpoint_interval</span> </span>
(<span class="paramdef">in <span class="parameter">minutes</span> integer</span>);
</div>
<div class="refsect1">
<div class="refsect1title">Description</div>
<p>This function changes the database checkpointing interval to the given
value in minutes. It may also be used to disable checkpointing in two
ways: By setting checkpoint interval to 0, the checkpoint will only be
performed after roll forward upon database startup. A setting of -1
will disable all checkpointing. Main use for this function is to
ensure a clean online backup of the database slices. Copying of the
database may take long and checkpointing would modify those files in
mid-copy, thus rendering the resulting copy unusable. In case the
system should, for some reason or another, become unstable, it is
sometimes better to disable checkpointing after a database restart
to resume backing up from where it was left prior to a system crash.
Disabling all checkpointing by giving checkpoint_interval the value
of -1 will do just that.</p>
<p>The interval setting will be saved in the server configuration
file as value of CheckpointInterval in section [Parameters], thus it
will persist over consecutive server shutdown/restart cycles. A
long checkpoint_interval setting will produce longer transaction
logs, which in turn prolongs the time it takes for the database to
perform a roll forward upon restart in case it was shut down without
making a checkpoint.</p>
</div>
<div class="refsect1">
<div class="refsect1title">Parameters</div>
<div class="refsect2">
<span class="refsect2title">minutes – </span>
<span class="computeroutput">integer</span> number of minutes between checkpoints.</div>
</div>
<div class="refsect1">
<div class="refsect1title">Return Types</div>
<p>Previous value of CheckpointInterval in the configuration file as an integer.</p>
</div>
<div class="refsect1title">Errors</div>
<p>
<a href="errors.html#datatypeerror">Parameter data type checking errors</a>
</p>
<p />
<div class="refsect1">
<div class="refsect1title">Examples</div>
<a name="ex_checkpoint_interval" />
<div class="example">
<div class="exampletitle">Simple examples</div>
<p>Disable checkpoints:</p>
<div>
<pre class="screen">SQL> checkpoint_interval(-1);
Done. -- 25 msec.
</pre>
</div>
<p>Re-enable checkpoints (every 2 hrs):</p>
<div>
<pre class="screen">SQL> checkpoint_interval(120);
callret
VARCHAR
______________________________________________________
-1
Done. -- 4 msec.
</pre>
</div>
</div>
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<div class="refsect1">
<div class="refsect1title">See Also</div>
<p>
<a href="fn_backup.html">backup</a>
</p>
<p>
<a href="databaseadmsrv.html#configsrvstupfiles">CheckpointInterval setting in Configuring Server Startup Files section</a>
</p>
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