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<Chapter Id="runtime">

algorithm: The pool size is the number of individuals in one

population. Valid values are between 128 and 1024. If it is

set to 0 (the default) a pool size of 2^(QS+1), where QS

is the number ofrelations in the query, is taken. The effort

is the number ofFROM items in the query, is taken. The effort

is used to calculate a default for generations. Valid values

are between 1 and 80, 40 being the default. Generations

specifies the number of iterations in the algorithm. The

<term>GEQO_THRESHOLD (<type>integer</type>)</term>

<listitem>

<para>

Only use genetic query optimization for queries with at least

this many relations involved. The default is 11. For less

relations it is probably more efficient to use the

Use genetic query optimization to plan queries with at least

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.

</para>

</listitem>