[[TOC]]
= Installation on PostgreSQL =
Replacing the simple SQLite database with [http://www.postgresql.org PostgreSQL] allows greater scalability & the possibility of [wiki:InstallationGuidelinesGISDataLinux#PostGIS using PostGIS for spatial storage].

Main install docs are here: [wiki:InstallationGuidelines/Linux/Server/CherokeePostgreSQL]

This page provides some supplementary notes

== Installation ==
It is assumed that you are running Debian 'squeeze'. 'lenny' works fine for Eden, but the main point is to use PostGIS where squeeze is better...

{{{
apt-get install -y postgresql-8.4 python-psycopg2
}}}

Enable automatic DB maintenance:
{{{
vim /etc/postgresql/8.4/main/postgresql.conf
# Enable remote access
listen_addresses = '*'
port = 5432
track_counts = on
autovacuum = on

vim /etc/postgresql/8.4/main/pg_hba.conf
host    all         all         my.ip.add.ress/24     md5

/etc/init.d/postgresql restart

vim /etc/iptables.rules
-A INPUT -p tcp --dport 5432 -j ACCEPT

reboot
}}}
NB Don't do remote access as 'postgres' - to do so means can't simply access psql via 'su postgres'

To log-in as user postgres (Debian/Ubuntu):
{{{
sudo su postgres
}}}

== Tuning ==
Adjust postgresql.conf for performance relative to resources available
 * http://wiki.postgresql.org/wiki/Tuning_Your_PostgreSQL_Server
 * http://linuxfinances.info/info/quickstart.html

{{{
vim /etc/sysctl.conf
# Increase Shared Memory available for PostgreSQL
# 512Mb
kernel.shmmax = 279134208
# 1024Mb (may need more)
#kernel.shmmax = 552992768
kernel.shmall = 2097152

sysctl -w kernel.shmmax=279134208
sysctl -w kernel.shmall=2097152

vim /etc/postgresql/8.4/main/postgresql.conf

# This default is probably ok
# adjust upward _or_ add a connection pooling layer like pgpool if running out of connections for clients
max_connections = 100

# shared_buffers = 24MB
# Ideal is if all frequently accessed indexes and table rows can fit in here - this is often unrealistic
# setting too high relative to system resources can be detrimental to the system.
# At the high end this should be 10-25% of available memory (ie that which is not being used by the OS or other processes).
# Values suggested are quite conservative, so you can push them up a bit if there are resources available for it
# but absolutely no more than 1/3 available memory.
# 512Mb system suggest starting at:
shared_buffers = 56MB
# 1024Mb system suggest starting at:
#shared_buffers = 160MB

# effective_cache_size = 128MB
# 75% of available memory
# 512Mb system suggest starting at:
effective_cache_size = 256MB
# 1024Mb system suggest starting at:
#effective_cache_size = 512MB

#work_mem = 1MB
# This is a per sort setting, so setting this too high with a high number of max_connections can be bad.
# If the database load turns out to have a lot of sorting and not a lot of separate connections, you should increase this
# and drop the max_connections.
# 512Mb system suggest starting at:
work_mem = 2MB
# 1024Mb system suggest starting at:
#work_mem = 4MB

# As you get more memory in the system, moving this up can be quite useful if you notice vacuum processes taking forever.
maintenance_work_mem = 16MB

/etc/init.d/postgresql restart
}}}

== Install Support Tools ==
(Optional) Install the Admin Pack for enhanced intrumentation:
{{{
apt-get install postgresql-contrib-8.4
su postgres
psql -d postgres -f /usr/share/postgresql/8.4/contrib/adminpack.sql
}}}

(Optional) Install [http://phppgadmin.sourceforge.net PHPPgAdmin] if you want a web-based management tool:
{{{
apt-get install phppgadmin
}}}
== Configure PostgreSQL for Sahana Eden ==
{{{
su postgres
createuser -s -P sahana

createdb -O sahana -E UTF8 sahana -T template0
}}}

If using [wiki:InstallationGuidelinesGISDataLinux#PostGIS PostGIS] (recommended) then:
{{{
apt-get install -y postgresql-8.4-postgis
su postgres
createlang plpgsql -d sahana
psql -d sahana -f /usr/share/postgresql/8.4/contrib/postgis-1.5/postgis.sql
psql -d sahana -f /usr/share/postgresql/8.4/contrib/postgis-1.5/spatial_ref_sys.sql
}}}
NOTE: you must install PostGIS first

Ubuntu users (Lucid/PostgreSQL 8.4/Post-GIS 1.4) - the paths are slightly different
{{{
psql -d sahana -f /usr/share/postgresql/8.4/contrib/postgis.sql
psql -d sahana -f /usr/share/postgresql/8.4/contrib/spatial_ref_sys.sql
}}}

== Install Python support for PostgreSQL ==
If not done as-per above instructions:
{{{
apt-get install python-psycopg2
}}}

== Configure Sahana Eden to use PostgreSQL ==
{{{
vim models/000_config.py
deployment_settings.database.db_type = "postgres"
deployment_settings.database.port = "" # use default
deployment_settings.database.database = "sahana"
deployment_settings.database.username = "sahana"
deployment_settings.database.password = "mypassword"
deployment_settings.database.pool_size = 30
}}}

'Connection pools' are used to reuse connections. How many pools should we use?
{{{
whatever you choose it always starts with one and grows with the number of concurrent requests up to the value of pools (the max number of concurrent pools).
So pools should be the max number of concurrent requests you expect. That is the max value of:
<number of requests/second> / <average time per request in seconds> 
}}}

== Add Geometry column to gis_location ==
If using PostGIS, then once the tables have been created:
{{{
cat << EOF > "/tmp/geometry.sql"
UPDATE public.gis_location SET wkt = 'POINT (' || lon || ' ' || lat || ')' WHERE gis_feature_type = 1;
SELECT AddGeometryColumn( 'public', 'gis_location', 'the_geom', 4326, 'GEOMETRY', 2 );
UPDATE public.gis_location SET the_geom = ST_SetSRID(ST_GeomFromText(wkt), 4326);
EOF
su -c - postgres "psql -q -d sahana -f /tmp/geometry.sql"
}}}
(if using Windows can use the Query Editor that comes with pgAdmin III)

Ensure that future entries auto-populate properly:
{{{
cat << EOF > "/tmp/autopopulate.sql"
CREATE OR REPLACE FUNCTION s3_update_geometry()
  RETURNS "trigger" AS \$$
  DECLARE
  BEGIN
    if (NEW.wkt != '') then
        NEW.the_geom = SetSRID(GeomFromText(NEW.wkt), 4326);
        end if;

    RETURN NEW;
  END;
\$$  LANGUAGE 'plpgsql' VOLATILE;
ALTER FUNCTION s3_update_geometry() OWNER TO sahana;
CREATE TRIGGER s3_locations_update
  BEFORE INSERT
  ON gis_location
  FOR EACH ROW
  EXECUTE PROCEDURE s3_update_geometry();

EOF
su -c - postgres "psql -q -d sahana -f /tmp/autopopulate.sql"
}}}

Tell Sahana that the DB is spatially-enabled so that routines can make use of this:
{{{
vim models/000_config.py
deployment_settings.gis.spatialdb = True
}}}
== Backups ==
{{{
su postgres
pg_dump -c sahana > /tmp/sahana.sql
pg_dump -Fc gis > /tmp/gis.dmp
}}}

== Maintenance ==
Connect to Database (or use pgAdmin III GUI's PSQL Console on plugins menu):
{{{
su postgres
psql
}}}
or
{{{
psql -d my_spatial_db -U username
}}}

List Databases:
{{{
\l
}}}

Connect to a Database:
{{{
\c sahana
}}}

List Tables:
{{{
\d
}}}

Describe Table structure:
{{{
\d tablename
select field/* from tablename where field = 'value';
}}}

If you need to build a fresh database:
{{{
rm -f /home/web2py/applications/eden/databases/*
su postgres
pkill -f 'postgres: sahana sahana'
dropdb sahana
createdb -O sahana -E UTF8 sahana
}}}

To restore data from backup:
{{{
su postgres
psql -f /tmp/sahana.sql
createdb gis
psql gis -f /usr/share/postgresql-8.4/contrib/postgis.sql
/usr/share/postgresql-8.4-postgis/utils/new_postgis_restore.pl -f /tmp/gis.dmp | psql gis
}}}

== Troubleshooting ==

 * http://wiki.postgresql.org/wiki/Performance_Optimization
 * http://wiki.postgresql.org/wiki/SlowQueryQuestions
 * http://www.revsys.com/writings/postgresql-performance.html
 * http://www.postgresql.org/docs/8.4/static/runtime-config-logging.html
 * http://www.depesz.com/index.php/2008/11/23/waiting-for-84-auto-explain/

Log all queries which take longer than 5s:
{{{
su postgres
psql
set log_min_duration_statement = 5000;
\q

tail -n 45 -f /var/log/postgresql/postgresql-8.4-main.log
}}}

Disable logging again:
{{{
su postgres
psql
set log_min_duration_statement = -1;
\q
}}}

Log all queries which take longer than 5s & do an 'EXPLAIN' on those queries (not working)
{{{
LOAD 'auto_explain';
set explain.log_min_duration = 5000;
}}}
== Also see ==
 * [wiki:InstallationGuidelinesGISDataLinux#PostGIS PostGIS Installation]
 * Setting up Web2Py with PostgreSQL on Ubuntu: http://www.web2pyslices.com/main/slices/take_slice/14

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InstallationGuidelines