IAM Role in AWS

by

In AWS IAM Roles are similar to IAM Users in that they can have policies and permissions attached to them. However, they cannot be authorized (login) and they do not really have the policies etc attached to them. They appear to have them but underneath, those policies flow down the the actual users beneath.

The idea is that Roles will help you to group users together and also that they can help you in temporarily granting a level of access or permission to a user and give you an easy way to revoke that.

Read more

AWS IAM Notes – AWS Solutions Architect

by

This is some rough notes on IAM in AWS, covering IAM Roles, IAM Users and IAM Policies. The notes are aims at studying for the AWS Solutions Architect Certification and should cover the main points required for that exam.

AWS IAM can be summed up by saying that it authenticates and authorities you to and in AWS.

Root user is first user and has all permissions to everything on the account. It can’t be removed.

Read more

Can you improve your Oracle database using Postgres?

by

Oracle is a great database. It is cutting edge and it has a huge team of developers behind it as well as massive funding.


There are not any areas where it lacks anything major that exists in other comparable databases.

The problem with Oracle is both that it is expensive in the first place, but also that all of the extras are chargeable and also expensive!

Read more

High Availability Options in Oracle vs Postgres

by

Oracle is the database to beat in terms performance and features or at least is positioned that way. More importantly, if you are thinking of migrating from Oracle to Postgres to save money, you need to know that your new database has at least the same features at the one that you are moving from.


High availability is one of the most important concepts and features for a database system. For most enterprise level applications, downtime has a direct financial cost and the actual loss of some or all of your data would be catastrophic. 
You need to know that the system that you are moving to can protect your data as well as the system that you are on at the moment.

Read more

Should you migrate to Postgres from Oracle?

by

The Oracle database has been the gold standard for enterprise applications for a long time now. It has great performance, solid reliability and most of the features that you could want are available. The big problem is that it is expensive. And I mean REALLY expensive. That’s just for the base product as well. All of the extra features that you might want are chargeable extras which means that wench developing for Oracle, you often have to work without some of the more advanced features because they would cost too much.

Read more

Postgres Vacuum and AutoVacuum.

by

Basics of vacuum Postgres maintains multi version consistency by keeping old versions of changes tuples instead of actually deleting them. Eventually, keeping all of those out of date versions becomes big burden in terms  of storage and performance. Eventually, you end up with bloated tableland indexes. If not felt with, eventually they would fill up tour disks but they would probably make the database unusable before then so we have a handy process to clean it all up. That is Vacuum. Postgres Vacuum goes through your tables and indexes an cleans out had tuples – that is tuples that can no longer be needed by a transaction.

Read more

Backing up and Restoring Postgres using pg_basebackup

by

There are several great tools available that handle backing up and managing the backups of your PostgresQL database. It is really important to understand the underlying process that these tools use though as well as the standard postgres commands are that you would need to run in case you ever need to do it manually.

There are 2 types of backups that you can take in Posgres, logical and physical. Logical backups are in the form if the SQL statements necessary to recreate the database (not necessarily in a human readable form). The 2 tools to take logical backups are pg_dump and pg_dumpall.

Read more

What is the pg_clog and the clog

by

There are several directories named log in a Postgres installation.

You have pg_xlog, pg_log and pg_clog.

These are all important but I’ll talk about the others another time.

Pg_clog is the commit log. It is generally a small folder that you should never have a reason to look at. (note that from version 10 of postgres the pg_clog directory is being renamed to pg_xact I will continue to refer to it as pg_clog in this document but the functioning of both is the same)

Importantly, you can never delete anything from that directory. If you do your database will become unusable and you will need to recreate it from a backup.

Read more

Setting up a Postgres test cluster in vagrant

by

Most of the time its fine to test things out on your local machine and local installation of Postgres but often, you want more flexibility, the ability to quickly reset to a known starting point and the ability to try out different and more complex server architectures.

That is where Vagrant comes in. I use it to quickly set up Postgres clusters at different versions and different configurations.

You can find all of these in my repo at https://github.com/philmcc/postgres_clusters

For example here is a set up to allow you to set up a 3 node cluster with 1 leader and 2 followers all on postgres 9.4 and using replication slots:

Read more