For more information and to download pgAdmin III, click here.

Enable slow query logging in PostgreSQL

• Open the file postgresql.conf file in your favorite text editor.
  Note: If you are having trouble finding the file, run the command: find / -name postgresql.conf
• Look for the line:
  #log_min_duration_statement = -1and replace it with:
  log_min_duration_statement = 100
• Save the file and reload the PostgreSQL configuration (Don’t worry, it won’t interrupt any active connections)
  service postgresql reload
• Go to the pg_log folder and open the latest log file. (i.e. /var/lib/pgsql/data/pg_log/)

Setting the value to 100 will log every query that takes 100ms or longer to execute. Depending on the number of slow queries you have, this may be overwhelming, so consider increasing this value.

If you need some assistance in optimizing your slow queries, feel free to post them in the comments section below!

Installing PostgreSQL 8.4.x on CentOS 5.5

• Download the PostgreSQL 8.4 repository RPM
  wget http://yum.pgsqlrpms.org/reporpms/8.4/pgdg-centos-8.4-2.noarch.rpm
• Add the repository
  rpm -ivh pgdg-centos-8.4-2.noarch.rpm
• Use yum to install PostgresSQL
  yum install -y postgresql postgresql-server
• Initialize the database
  service postgresql initdb
• Start the database
  service postgresql restart
• Automatically start database on boot
  chkconfig postgresql on

1. Open a connection to your database using psql or GUI tool
2. Run the command:

select pg_stat_reset();

Option 1: From the command-line shell

su - postgres
/usr/bin/pg_ctl reload

Option 2: Using SQL

SELECT pg_reload_conf();

Using either option will not interrupt any active queries or connections to the database, thus applying these changes seemlessly.

1. Login to the PostgresSQL command-line interface

psql -U [username] [database_name]

2. Run the following query:

select t.relname,l.locktype,page,virtualtransaction,pid,mode,granted from pg_locks l, pg_stat_all_tables t where l.relation=t.relid order by relation asc;


1. Login to the PostgresSQL command-line interface

psql -U [username] [database_name]

2. Run the following query:

SELECT datname,usename,procpid,client_addr,waiting,query_start,current_query FROM pg_stat_activity;


1. Login to the PostgresSQL command-line interface

psql -U [username] [database_name]

2. Run the following query:

select relname,last_vacuum, last_autovacuum, last_analyze, last_autoanalyze from pg_stat_user_tables;

1. Login to the PostgresSQL command-line interface

psql -U [username] [database_name]

2. Show a list of constraints on a particular table

\d [table_name]

3. To Delete (or Drop) the constraint, use the command:

ALTER TABLE [table_name] DROP CONSTRAINT [constraint_name];

Example 1 – Using awk

Number: 52.4

echo "52.4" | awk 'BEGIN {FS="."}{print $1, $2}'
Output: 52 4

echo "52.4" | awk 'BEGIN {FS="."}{print $1}'
Output: 52

echo "52.4" | awk 'BEGIN {FS="."}{print $2}'
Output: 4

Example 2 – Using cut

Number: 1.0.2.66

echo "1.0.2.66" | cut -d. -f1
Output: 52 4

echo "1.0.2.66" | cut -d. -f2
Output: 0

echo "1.0.2.66" | cut -d. -f3
Output: 2

echo "1.0.2.66" | cut -d. -f4
Output: 66

There you have it, two different methods for parsing decimal numbers!