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<chapter id="overview">

<title>Overview of PostgreSQL Internals</title>

<listitem>

<para>

<firstterm>mergesortjoin</firstterm>: Each relation is sorted on the join

<firstterm>merge join</firstterm>: Each relation is sorted on the join

attributes before the join starts. Then the two relations are

scanned in parallel, and matching rows are combined to form

join rows. This kind of join is more