Author Archives: ronaldpringadi

VirtualBox – Imporving usability on guest OS

Posted on May 17, 2016 by ronaldpringadi

GUEST OS: Centos 6.7 final HOST OS: Windows 7 Virtualbox version: 5.0.4 1yum install gcc kernel-devel kernel-headers dkms make bzip2 perl

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RedHat or CentOS 6 iptables adding an open port

Posted on May 16, 2016 by ronaldpringadi

iptables –line -vnL iptables -I INPUT 5 -p tcp –dport 80 -m state –state NEW,ESTABLISHED -j ACCEPT service iptables save

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Postgres SSD optimization

Posted on April 13, 2016 by ronaldpringadi

If you’re running your database on an SSD instead of a spinning disk, you might want to optimize postgres table space cost: 12345678910– Change the tablespace cost ALTER TABLESPACE pg_default SET ( seq_page_cost = 20,  random_page_cost = 1 ); — … Continue reading →

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Ant Junit debugging

Posted on April 13, 2016 by ronaldpringadi

Sometime we want to debug why ant build failed when executing a certain JUnit Make sure your ant junit task look like the following 1234<junit printsummary="withOutAndErr" haltonfailure="yes"> : : </junit> and not like 1234<junit printsummary="yes" haltonfailure="yes"> : : </junit>

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Delete Postgres Cache

Posted on April 13, 2016 by ronaldpringadi

1234#!/bin/bash sync echo 1 > /proc/sys/vm/drop_caches service postgresql-9.3 restart

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Java Flight Recorder: a profiler that’s already in your JVM

Posted on March 22, 2016 by ronaldpringadi

If you’re running anything on the JVM (Java Virtual Machine) in production and you’ve never opened a Flight Recorder file, you’re leaving a free profiler on the table. Java Flight Recorder (JFR) is a low-overhead event recorder built into the … Continue reading →

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Check which database object depends on (has reference to) your table

Posted on February 12, 2016 by ronaldpringadi

12345678910111213141516SELECT R.TABLE_NAME FROM INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE u INNER JOIN INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS FK     ON U.CONSTRAINT_CATALOG = FK.UNIQUE_CONSTRAINT_CATALOG     AND U.CONSTRAINT_SCHEMA = FK.UNIQUE_CONSTRAINT_SCHEMA     AND U.CONSTRAINT_NAME = FK.UNIQUE_CONSTRAINT_NAME INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE R     ON R.CONSTRAINT_CATALOG = FK.CONSTRAINT_CATALOG     AND … Continue reading →

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Postgres function to devide-and-conquer (iterate) your big query

Posted on February 8, 2016 by ronaldpringadi

Create a postgres function to devide-and-conquer (iterate) your big query 1234567891011121314151617181920212223242526272829303132333435363738394041TRUNCATE TABLE YOUR_NEW_BIG_TABLE; DROP FUNCTION IF EXISTS pg_iterator(); CREATE OR REPLACE FUNCTION pg_iterator()   RETURNS void AS $BODY$ DECLARE     vOffsetRecord INT;     vTotal INT;     vLimit … Continue reading →

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Crontab header

Posted on February 1, 2016 by ronaldpringadi

123456# minute (0-59), # |      hour (0-23), # |      |       day of the month (1-31), # |      |       |       month of the year (1-12), # … Continue reading →

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Add user in mysql

Posted on January 17, 2016 by ronaldpringadi

The classic three-liner for adding a MySQL user, run from a mysql shell connected as root or another account with the CREATE USER privilege. Replace each placeholder with your own value. 123CREATE USER ‘YOUR_USER_NAME’@’CONNECTING_FROM_WHERE’ IDENTIFIED BY ‘THIS_USER_PASSWORD’; GRANT ALL PRIVILEGES … Continue reading →

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