Generate PostgreSQL optimized memory parameters

autotunnig.sh

#!/bin/bash
# 
# autotunning.sh 

# Constants
TWO_GIGABYTES="2056772"

# Variables

# Utils
removeTabs(){ tr '\t' '@' | sed 's/@//'; }
int(){ echo "$1" | sed 's/\..*//'; }
print(){ echo "$@" >&2; }
return(){ echo "$@"; }
math(){ echo "$@" | bc -l; }
toMB(){
    gb=`math "$1 / 1024 / 1024"`
	return "`int $gb`mb"
}

# Functions
get_ram_memory(){
	memline=`cat /proc/meminfo | tr '\t' ' ' | sed 's/  */ /g;/MemTotal/!d'`
	mem=`echo $memline | cut -d ' ' -f 2`
	mult=`echo $memline | cut -d ' ' -f 3 | sed 's/kb/1024/ig;s/mb/1024*1024/gi;s/gb/1024*1024*1024/gi'`
	return `math "${mem} * ${mult}"`
}

get_shared_buffers(){
	ram_memory=`get_ram_memory`
	shared_buffers=""
	if [ "$ram_memory" -gt "$TWO_GIGABYTES" ]; then
		shared_buffers=`math "$ram_memory * 0.20"`
	else
		shared_buffers=`math "$ram_memory * 0.25"`
	fi
	return `toMB $shared_buffers`
}

get_work_mem(){
	return "64MB"
}

get_maintenance_work_mem(){
	ram_memory=`get_ram_memory`
	maintenance_work_mem=`math "$ram_memory * 0.10"`
	return `toMB $maintenance_work_mem`
}

get_effective_cache_size(){
	return "16mb"
}

# main

cat<<EOF | removeTabs
	shared_buffers = `get_shared_buffers`
	work_mem = `get_work_mem`
	maintenance_work_mem = `get_maintenance_work_mem`
	effective_cache_size = `get_effective_cache_size`
	wal_buffers = 16mb
	checkpoint_completion_target = 0.9
	checkpoint_timeout = 10m
EOF

Based on excellent post about PostgreSQL tunning:
http://reinout.vanrees.org/weblog/2012/06/04/djangocon-postgres.html