Apache is the widely used web server, and PHP is a dominant technology when it comes to CMS frameworks i.e. WordPress, Drupal, etc. For this reason the deployment of the stack has been made effortless with XAMPP PHP development environment. XAMPP is an acronym, where X stands for any operating system (WAMP for Windows, LAMP for Linux), A for Apache web server, M for MySQL or MariaDB database engine, and PP stands for PHP and Perl. The post is about setting-up PHP development environment XAMPP on Ubuntu 16.04, suing terminal.
Step 0 – Login and update
First of all login into your Ubuntu machine using SSH – for a regular it’s recommended to add your SSH public key
Continue reading “Install XAMPP stack on Ubuntu 16.04 using terminal”
SSH stands for Secure SHell, a tool developed by SSH Communication Security Ltd, for secure remote log-in and command execution. It’s a secure alternative of it’s predecessors rlogin, rsh, etc. SSH has become industry de-facto for securely communicating with remote machines i.e. the entire session is encrypted.
The SSH is based on public-key cryptography
(also known as asymmetric cryptography), a cryptography system employing key pair i.e. a public key
which is meant to be shared, and private key
which has to be kept safe and secret, only known to the owner. This pair serves two purpose 1. authentication, the public key verifies the owner of the paired private key, and 2. encryption, the public key encrypts the message, and only the paired private key can decrypt it. In simple words, you can share your public key
(content of ~/.ssh/id_rsa.pub) with anyone via email, for example: to access a remote machine securely and without password, all you need to do is copy your public key to authorized_keys (default – ~/.ssh/authorized_keys) file.
Continue reading “All you need to know about SSH”
Database partitioning is about logically splitting one large table into smaller physical pieces, such that improving query performance. DB partitioning is a good alternate for indexing multiple columns, reducing index size, hence the memory in use. Few common pros of database partitioning:
- Improved performance – data operations (CRUD) can be performed on a smaller volume of data, for example, in case of collecting data overtime, putting old data in separate partition might help with performance.
- Bulk create and delete can be efficient by adding or removing separate partitions.
- Time based partition can be helpful in cleaning old seldom-used data i.e. month based partition we can simply set a cron job for cleaning 12 month old partition, without effecting the table portion heavily in use for ADD, UPDATE, etc.
- Improved scalability – In case of very large tables, you can partition and have them hosted on a separate server.
There are 2 main approaches to database partitioning:
- Horizontal partitioning (Sharding) – a table is split horizontally, such that each partition is a subset of the table, having the same schema (i.e. number of fields/columns).
- Vertical partitioning – a table is split on the fields/columns, such that each subset has separate schema. A common use-case for vertical partitioning is to partition table fields on the basis of pattern of use i.e. frequently accessed fields are to be grouped together, and the less frequently accessed are put in a separate partition.
This blog post is about setting automatic horizontal partitioning (month based) on a table in PostgreSQL.
The high-level steps are:
- Create table, or select an existing one.
- Execute partitioning function or procedure
- Table trigger – to call the partition procedure.
- View for parent-child tables (optional)
Step 1 – Create Table
CREATE TABLE partition_test(id BIGINT, created_datetime DATE);
Step 2 – Trigger function
CREATE OR REPLACE FUNCTION test_partition_function() RETURNS trigger AS
partition_date := to_char(NEW.created_datetime,'YYYY_MM');
partition := TG_RELNAME || '_' || partition_date;
IF NOT EXISTS(SELECT relname FROM pg_class WHERE relname=partition) THEN
RAISE NOTICE 'A partition has been created %',partition;
EXECUTE 'CREATE TABLE ' || partition || ' () INHERITS (' || TG_RELNAME || ');';
EXECUTE 'INSERT INTO ' || partition || ' SELECT(' || TG_RELNAME || ' ' || quote_literal(NEW) || ').* RETURNING id;';
LANGUAGE plpgsql VOLATILE
Step 3 – Table trigger
CREATE TRIGGER partition_test_trg
AFTER INSERT ON partition_test
FOR EACH ROW EXECUTE PROCEDURE test_partition_function();
Step 4 – Viewing the partition (optional)
CREATE VIEW show_partitions AS
SELECT nmsp_parent.nspname AS parent_schema,
parent.relname AS parent,
nmsp_child.nspname AS child_schema,
child.relname AS child
JOIN pg_class parent ON pg_inherits.inhparent = parent.oid
JOIN pg_class child ON pg_inherits.inhrelid = child.oid
JOIN pg_namespace nmsp_parent ON nmsp_parent.oid = parent.relnamespace
JOIN pg_namespace nmsp_child ON nmsp_child.oid = child.relnamespace
WHERE parent.relname='partition_test' ;
Step 5 – Verification (optional)
Let’s test using the show_partitions view, if we have any partitions yet
select * from show_partitions;
insert in partition_test
insert into partition_test values (1, '2018-01-19');
Few more inserts for the same month
insert into partition_test values (2, '2018-01-22');
insert into partition_test values (3, '2018-01-29');
Continue reading “DB partition trigger with PostgreSQL”