<row>

<entry>columns per table</entry>

<entry>1600</entry>

<entry>1,600</entry>

<entry>further limited by tuple size fitting on a single page; see note

below</entry>

</row>

<row>

<entry>columns in a result set</entry>

<entry>1664</entry>

<entry>1,664</entry>

<entry></entry>

</row>

<entry></entry>

</row>

<row>

<entry>identifier length</entry>

<entry>63 bytes</entry>

<entry>can be increased by recompiling <productname>PostgreSQL</productname></entry>

</row>

<row>

<entry>indexes per table</entry>

<entry>unlimited</entry>

<entry>can be increased by recompiling <productname>PostgreSQL</productname></entry>

</row>

<row>

<entry>partition keys</entry>

<entry>32</entry>

<entry>can be increased by recompiling <productname>PostgreSQL</productname></entry>

</row>

<row>

<entry>partition keys</entry>

<entry>32</entry>

<entry>can be increased by recompiling <productname>PostgreSQL</productname></entry>

</row>

<row>

<entry>identifier length</entry>

<entry>63 bytes</entry>

<entry>can be increased by recompiling <productname>PostgreSQL</productname></entry>

</row>

<row>

<entry>function arguments</entry>

<entry>100</entry>

<entry>can be increased by recompiling <productname>PostgreSQL</productname></entry>

</row>

<row>

<entry>query parameters</entry>

<entry>65,535</entry>

<entry></entry>

</row>

</tbody>

</tgroup>

</table>

<para>

The maximum number of columns for a table is further reduced as the tuple

being stored must fit in a single 8192-byte heap page. For example,

excluding the tuple header, a tuple made up of1600 <type>int</type> columns

excluding the tuple header, a tuple made up of1,600 <type>int</type> columns

would consume 6400 bytes and could be stored in a heap page, but a tuple of

1600 <type>bigint</type> columns would consume 12800 bytes and would

1,600 <type>bigint</type> columns would consume 12800 bytes and would

therefore not fit inside a heap page.

Variable-length fields of

types such as <type>text</type>, <type>varchar</type>, and <type>char</type>