Category Archives: Uncategorized

So for this months blog we are going to delve into adding a new EBS Volume to an EC2 instance and although this is a reasonably simple operation, we will drill down into some of the options you have and how these can impact performance long-term. We will look at the following: GPT v MBRContinue reading “All you need to know about adding a new EBS Volume”

So everyday at work we use AWS DMS for replicating data from our core main databases which are SQL Server instances installed on EC2 machines to various data stores in the AWS cloud. And don’t get me wrong this is a great service that is super fast and also fairly durable but there are aContinue reading “AWS DMS Hidden Gotcha’s Part I”

So lets say that you want to add/drop a column from an existing Capture Instance but don’t want to lose any data that is currently in the capture instance and also you cannot afford to have any downtime, how do you achieve this. Please read on to find out. So Microsoft have provided you withContinue reading “Modifying an Existing Capture Instance in MS SQL Server CDC”

The Data Migration Service or DMS for short is one of AWS’s most useful service. It allows you to migrate data from one data source to another, provided at least one of the those data sources. Before we get into the main topic of this article, ‘Explaining the Recovery Checkpoint’ of DMS, lets have aContinue reading “AWS DMS Replication Recovery Checkpoint”

Ok, not the most exciting topic in the world, but before you blow off reading this months blog know this, the collations that you have set at a database level in PostgreSQL impact the storage engines ability to be able to use an Index on a wild card search. Say what? Yes you heard meContinue reading “Collations and Encoding – PostgreSQL”

So you might be aware that PostgreSQL uses MVCC to handle transaction isolation and this has loads of advantages such as – Very few locks are required, meaning readers don’t block writers and writers don’t block readers. ROLLBACK can be very fast as it does not have to undo any changes. So what is MVCC?Continue reading “HOT Updates – PostgreSQL”

When storing a string in SQL Server we use either char(n), varchar(n), nchar(n) and nvarchar(n). So what really is the difference? So we might know that char and varchar store Ascii characters and use 1 byte per character to store this data, where as nchar and nvarchar store Unicode characters and use 2 bytes perContinue reading “UTF-16 and UTF-8 Encoding – SQL Server”

Recently at work we had a requirement to change an existing column on a table from NULL to NOT NULL. Now the column in question (call it ColumnA) was belonged to a very large table, (over 1 billion rows) and for a lot of the rows in this table that column was null. Rather thanContinue reading “CDC Anomaly with Metadata-Only change with Default Constraint – SQL Server”

We have some postgres functions at my work where wildcard searches are done, where both the wildcard symbol % is added to the front and back of the search term. By prefixing the symbol to the front of search term this means that a B-Tree index cannot be used in the searching and so aContinue reading “Trigrams – PostgreSQL”