k-NN algorithm, <filename>aqo</filename> improves cardinality estimation, which can optimize execution plans and, consequently, speed up query execution.

</para>

<para>The <filename>aqo</filename> module can collect statistics on all the executed

queries differ in their constants only, they belong to the same

type. For each type, <filename>aqo</filename> stores the cardinality quality, planning

time, execution time, and execution statistics for machine learning. Based on this data, <filename>aqo</filename> builds a new query plan and uses it for the next query of the same type.