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| <dl class="user"><dt><b>About:</b></dt><dd>This function computes the specified quantile value. It reads the name of the table, the specific column, and computes the quantile value based on the fraction specified as the third argument.</dd></dl> |
| <p>For an implementation of quantile using sketches, check out the <a class="el" href="sketch_8sql__in.html#a2f2ab2fe3244515f5f73d49690e73b39" title="cmsketch_centile is a scalar UDF to compute a centile value from a cmsketch. Takes the results of the...">cmsketch_centile()</a> aggregate in the <a class="el" href="group__grp__countmin.html">CountMin (Cormode-Muthukrishnan)</a> module.</p> |
| <dl class="user"><dt><b>Implementation Notes:</b></dt><dd>There are two implementations of quantile available depending on the size of the table. <code>quantile</code> is best used for small tables (e.g. less than 5000 rows, with 1-2 columns in total). For larger tables, consider using <code>quantile_big</code> instead.</dd></dl> |
| <dl class="user"><dt><b>Usage:</b></dt><dd><pre>SELECT * FROM quantile( '<em>table_name</em>', '<em>col_name</em>', <em>quantile</em>);</pre> <pre>SELECT * FROM quantile_big( '<em>table_name</em>', '<em>col_name</em>', <em>quantile</em>);</pre></dd></dl> |
| <dl class="user"><dt><b>Examples:</b></dt><dd></dd></dl> |
| <ol type="1"> |
| <li>Prepare some input: <div class="fragment"><pre class="fragment"> |
| sql> CREATE TABLE tab1 AS SELECT generate_series( 1,1000) as col1; |
| </pre></div></li> |
| <li>Run the <a class="el" href="quantile_8sql__in.html#a6955e44659a0817803ab7a11a9a7e8a5" title="Computes quantile.">quantile()</a> function:<br/> |
| <div class="fragment"><pre class="fragment"> |
| sql> SELECT quantile( 'tab1', 'col1', .3); |
| |
| quantile |
| -------------- |
| 301.48046875 |
| (1 row) |
| </pre></div></li> |
| </ol> |
| <dl class="see"><dt><b>See also:</b></dt><dd>File <a class="el" href="quantile_8sql__in.html" title="SQL function for Quantile.">quantile.sql_in</a> documenting the SQL function.<br/> |
| <br/> |
| Module <a class="el" href="group__grp__countmin.html">CountMin (Cormode-Muthukrishnan)</a> for an approximate <a class="el" href="quantile_8sql__in.html#a6955e44659a0817803ab7a11a9a7e8a5" title="Computes quantile.">quantile</a> implementation. </dd></dl> |
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