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<Chapter Id="runtime">
this many FROM items involved. (Note that a JOIN construct
counts as only one FROM item.) The default is 11. For simpler
queries it is usually best to use the
- deterministic, exhaustive planner.
+ deterministic, exhaustive planner. This parameter also controls
+ how hard the optimizer will try to merge subquery
+ <literal>FROM</literal> clauses into the upper query.
</para>
</listitem>
</varlistentry>