FROM access_log

WHERE url = '/index.html' AND client_ip = inet '212.78.10.32';

</programlisting>

A query that cannot use this index is:

Here the query's IP address is covered by the partial index. The

following query cannot use the partial index, as it uses an IP address

that is excluded from the index:

<programlisting>

SELECT *

FROM access_log

WHERE client_ip = inet '192.168.100.23';

WHEREurl = '/index.html' ANDclient_ip = inet '192.168.100.23';

</programlisting>

</para>

<para>

Observe that this kind of partial index requires that the common

values be predetermined, so such partial indexes are best used for

data distributions that do not change.The indexes can be recreated

data distributions that do not change.Such indexes can be recreated

occasionally to adjust for new data distributions, but this adds

maintenance effort.

</para>