PostGreSQL

create user <username> createdb createuser;

alter user <username> with password '<password>';

ALTER TABLE <table> ALTER COLUMN <column> TYPE <new_type>;

BEGIN;
ALTER TABLE <table> ADD COLUMN <new_column> <new_type>;
UPDATE <table> SET <new_column> = CAST(<old_column> AS <new_type>);
ALTER TABLE <table> DROP COLUMN <old_column>;
COMMIT;

ALTER TABLE <table> ADD CONSTRAINT table_column_key UNIQUE (<column>);

ALTER TABLE <table> DROP CONSTRAINT <constraint>;

In postgresql.conf:

log_statement = 'all'

In postgresql.conf:

stats_command_string = true

Then look at table pg_stat_activity

Example:

UPDATE region SET code='0'||id;

Example:

SELECT NEXTVAL('hibernate_sequence');

/etc/postgresql/8.1

tail /var/log/postgresql/postgresql-8.1-main.log

In /etc/postgresql/8.1/main/pg_hba.conf:

host    all         all         206.12.30.0    255.255.255.0      md5

In /etc/postgresql/8.1/main/postgresql.conf:

listen_addresses = '*'

SELECT schemaname, tablename,
pg_size_pretty(size) AS size_pretty,
pg_size_pretty(total_size) AS total_size_pretty
FROM (SELECT *,
pg_relation_size(schemaname||'.'||tablename) AS size,
pg_total_relation_size(schemaname||'.'||tablename) AS total_size
FROM pg_tables) AS TABLES
ORDER BY total_size DESC;

Source: http://www.postgresql.org/docs/8.2/interactive/functions-admin.html#FUNCTIONS-ADMIN-DBSIZE

SELECT 	loid,
pg_size_pretty(count(*) * 2048)
FROM pg_catalog.pg_largeobject
GROUP BY loid
ORDER BY count(*) DESC;