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Update commentary in sample GEQO config file.

This commit is contained in:
Tom Lane 1999-05-22 23:59:59 +00:00
parent b2f14e11ec
commit 795f6ca66a
1 changed files with 17 additions and 9 deletions
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26
src/backend/optimizer/geqo/pg_geqo.sample
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@ -12,27 +12,30 @@
# utesch@aut.tu-freiberg.de * Freiberg, Germany *
#*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
# this file should be '$PGDATA/pg_geqo', but it doesn't have
# to exist
# To make this file do something, copy it to '$PGDATA/pg_geqo'
# and edit parameters to taste.
# If '$PGDATA/pg_geqo' doesn't exist, the system will use default parameters.
# The file is re-read for every GEQO optimization, if it does exist.
# comment character is '#'
#
# separator between recognized tag and possible value
# must be white space
# qs: means query size, which is the number of relations
# QS: means query size, which is the number of relations
# contained in a query
#=================+===================+=============================+
# RECOGNIZED TAGS | POSSIBLE VALUES | DEFAULTS |
#=================+===================+=============================+
# 'Pool_Size' | positive int | 2^(qs+1) |
# 'Pool_Size' | positive int | 2^(QS+1), but not less than |
# | | 128 nor more than 1024. |
#-----------------+-------------------+-----------------------------+
# 'Effort' | [low,medium,high] | medium |
#-----------------+-------------------+-----------------------------+
# 'Generations' | positive int | 'Effort' * log2('Pool_Size')|
# 'Generations' | positive int | Effort * log2(Pool_Size) |
#-----------------+-------------------+-----------------------------+
# 'Selection_Bias'| [1.50; 2.00] | 2.0 |
# 'Selection_Bias'| [1.50 .. 2.00] | 2.0 |
#-----------------+-------------------+-----------------------------+
# 'Random_Seed' | positive long | time(NULL) |
#=================+===================+=============================+
@ -41,15 +44,20 @@
# It gives us the number of individuals within one population.
#
# 'Effort' 'low' means integer value of 1, 'medium' 40, and 'high' 80.
# Note: Effort is *only* used to derive a default value for Generations
# --- if you specify Generations then Effort does not matter.
#
# 'Generations' gives us the stopping criterion for the number
# of iterations within the genetic algorithm.
# 'Generations' specifies the number of iterations in the genetic algorithm.
#
# GEQO runtime is roughly proportional to Pool_Size + Generations.
#
# 'Selection_Bias' gives us the selective pressure within the
# population.
#
# 'Random_Seed' is the random seed for the random() function.
# You don't have to set it.
# You don't have to set it. If you do set it, then successive GEQO
# runs will produce repeatable results, whereas if you don't set it
# there will be some randomness in the results...
# All parameters will be computed within the GEQO module when they
# are not set in the pg_geqo file.