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<h1>22. Virtuoso Functions Guide - SYS_DB_STAT</h1>
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<h2>SYS_DB_STAT</h2>
<div class="refpurpose">gathers common statistical information about the database.</div>
<div class="funcsynopsis">
<span class="funcdef"> <span class="function">SYS_DB_STAT</span>
</span>
(<span class="paramdef">in <span class="parameter">pcnt</span> integer</span>,
<span class="paramdef">in <span class="parameter">ignore_vdb</span> integer</span>);
</div>
<div class="refsect1">
<div class="refsect1title">Description</div>
<p>The <span class="computeroutput">SYS_DB_STAT</span> procedure gathers common
information about the whole Virtuoso database, including attached remote tables. It traverses
each table and populates the SYS_COL_STAT table with data collected. SYS_DB_STAT can
be used in random mode when not all rows of the tables are used to gather statistics
of the database.</p>
<p>
<span class="computeroutput">SYS_DB_STAT</span> gathers the following information
for each column, COL, traversed in the database:</p>
<ul>
<li>SYS_COL_STAT - SQL command </li>
<li>CS_N_DISTINCT - count (distinct XXX)</li>
<li>CS_MIN - min (XXX)</li>
<li>CS_MAX - max (XXX)</li>
<li>CS_AVG_LEN - avg (raw_length (XXX))</li>
<li>CS_N_VALUES - count (XXX)</li>
<li>CS_N_ROWS - count (XXX)</li>
</ul>
</div>
<div class="refsect1">
<div class="refsect1title">Parameters</div>
<div class="refsect2">
<span class="refsect2title">pcnt – </span>
Rate that affects percentage of database coverage. Zero means that the whole database is read. The default is 5, for a random sample of approximately 5 percent of each table.
</div>
<div class="refsect2">
<span class="refsect2title">ignore_vdb – </span>
By default SYS_DB_STAT does not analyze the remote tables. To
allow statistics gathering over linked tables, set this parameter to zero.
Remote tables can be very large or access to them can be very slow or both.
If this parameter is set to zero and pcnt is zero, SYS_DB_STAT will read the remote tables from start to end which may take very long. If pcnt is non-zero, this function will use its knowledge of the remote DBMS to get statistics in a DBMS specific manner if the DBMS is supported. See sys_stat_vdb_mappers table.</div>
</div>
<div class="refsect1">
<div class="refsect1title">Return Types</div>
<p>None.</p>
</div>
<div class="refsect1">
<div class="refsect1title">See Also</div>
<p>
<a href="fn_sys_stat_histogram.html">sys_stat_histogram</a>
</p>
<p>
<a href="fn_sys_stat_analyze.html">sys_stat_analyze</a>
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