## page was renamed from InstallPostgreSQLCentOS
= Postgresql =
PostgreSQL is a powerful, open source object-relational database system. It has more than 15 years of active development and a proven architecture that has earned it a strong reputation for reliability, data integrity, and correctness. It runs on all major operating systems, including Linux, UNIX (AIX, BSD, HP-UX, SGI IRIX, Mac OS X, Solaris, Tru64), and Windows. It is fully ACID compliant, has full support for foreign keys, joins, views, triggers, and stored procedures (in multiple languages). It includes most SQL:2008 data types, including INTEGER, NUMERIC, BOOLEAN, CHAR, VARCHAR, DATE, INTERVAL, and TIMESTAMP. It also supports storage of binary large objects, including pictures, sounds, or video. It has native programming interfaces for C/C++, Java, .Net, Perl, Python, Ruby, Tcl, ODBC, among others, and exceptional documentation.

http://www.postgresql.org/about/

== Install Postgresql on CentOS 6.4 ==

These installation steps should also apply to other distros based on RedHat source RPMs.

Logged in as root on the system run the following commands:
 * yum install postgresql
 * yum install postgresql-devel
 * yum install postgresql-server
 * service postgresql initdb
 * chkconfig postgresql on
 * service postgresql start

Edit the file ''' /var/lib/pgsql/data/pg_hba.conf  '''
 * local all all ident
 * host all all 0.0.0.0/0 password

To restart the postgresl DB run the command: 
 * service postgresql restart

== Check postgresql version ==
{{{#!highlight bash
cat /var/lib/pgsql/data/PG_VERSION
}}}

== Create postgresql test user and database ==
 * su postgres
 * psql
{{{#!highlight sql
create user appuser with login password '12345678';
create database app;
grant all privileges on database app to appuser;
}}}
 * \q

== Configure postgresql to accept all TCP connections ==
Edit the file ''' /var/lib/pgsql/data(postgresql.conf '''
 * listen-address="*"
 * port = 5432
 * max_connections = 100

Restart again the postgresl DB: 
 * service postgresql restart

== Test the connection using the user and password ==
psql -U appuser -h 127.0.0.1 -W -d a++

== Backup and restore with pg_dump ==
 * su postgres
 * pg_dump databasex > /var/lib/pgsql/backDatabasex.sql
 * psql databasex < /var/lib/pgsql/backDatabasex.sql # restore

== Daily backup script ==
{{{#!highlight bash
#!/bin/sh
#backupDBs.sh
#chmod 755 backupDBs.sh 
#backup database postgresql
#crontab -e 
#@daily /var/lib/pgsql/backupDBs.sh
BACKUPFOLDER=/var/lib/pgsql/backups
CURRDATE=`date -u "+%Y-%m-%dT%H:%m:%S.%Z"`
FILE=$BACKUPFOLDER/backup$CURRDATE.sql
DATABASE=dbx
/usr/bin/pg_dump $DATABASE > $FILE
gzip $FILE
}}}

== Show table structure ==
 * su postgres
 * \c databasex
 * \dt
 * \d+ tablex

== Drop a table column ==
 * su postgres
 * \c databasex
 * alter table tablex drop column columnx;

== Epoch from date field ==
Number of seconds since 1st January 1970 UTC.

{{{#!highlight sql
SELECT field1, field2, field3, extract(epoch from begindate) as begindate,extract(epoch from enddate) as enddate 
FROM tableX 
}}}

== Garbage-collect and analyze a PostgreSQL database ==
Create file /var/lib/pgsql/vacuumdb.sh and chmod 755 it
{{{#!highlight bash
#!/bin/sh
/usr/bin/vacuumdb --all --analyze --verbose
}}}

Create cron job to user postgres, crontab -e
{{{
@daily /var/lib/pgsql/vacuumdb.sh
}}}

== Install in debian buster ==
{{{#!highlight sh
apt install postgresql-11
netstat -at -n | grep 5432
ss -a -n | grep 5432
}}}

== Give super user rights to user ==
{{{#!highlight sql
ALTER USER appuser WITH SUPERUSER;
ALTER USER appuser WITH NOSUPERUSER;
}}}

== List databases ==
 * su postgres
 * psql
 * postgres=# \l