> [!NOTE] Table Function Scan
> <table>
> <tr>
> <td width="25%"><img src="assets/ex_tablefuncscan.png"></td>
> <td>Executes functions that return a set of rows (e.g., <code>xmltable</code> or <code>jsonb_to_recordset</code>). The engine calls the function and then treats its output as a virtual table that can be scanned, filtered, or joined like any other relation.</td>
> </tr>
> </table>
>
> ```sql
> -- Querying a generated XML table
> EXPLAIN (ANALYZE, COSTS, BUFFERS, VERBOSE)
> SELECT * FROM xmltable('/root/item'
> PASSING '<root><item>1</item><item>2</item></root>'
> COLUMNS i int PATH '.');
> ```
>
> 
>
> ```text
> Table Function Scan on "xmltable" (cost=0.00..1.00 rows=100 width=4) (actual time=0.030..0.030 rows=2 loops=1)
> Output: i
> Table Function Call: XMLTABLE(('/root/item'::text) PASSING ('<root><item>1</item><item>2</item></root>'::xml) COLUMNS i integer PATH ('.'::text))
> Planning Time: 0.030 ms
> Execution Time: 0.045 ms
> ```
>
> 
>
> <table>
> <tr>
> <td rowspan="2" width="25%"><img src="assets/ex_table_func_scan.svg"></td>
> <td><b>Performance</b></td><td>Depends on the complexity and volume of the generated table.</td>
> </tr>
> <tr><td><b>Cost</b></td><td><code>function cost + cpu_tuple_cost * number of rows</code></td></tr>
> </table>