Step Ahead Software

Displaying large datasets There are often times when you need to display data in a table format and the size of the potential dataset is extremely large and so ends up being represented across many pages and displayed with the usual "previous/next" buttons. Most UI frameworks need to know upfront what is the total count of items you will be displaying so they know how many pages there are and can display some text above the table that says something like: Items 31-40 of 397 Avoiding a big database, memory and CPU hit What you don't want to do is force your JDO ORM (or an ORM using any Java persistence standard e.g. JPA) from instantiating ALL of the objects just so that your UI knows the total count of items to be displayed. To do this you need to perform some kind of 'count' query. In JDO this is done by setting the result set to 'count' but count needs a parameter. e.g. PersistenceManager pm = getPm(); Query q = pm.newQuery(MyClass.class);          /

Our web hosting application platform Pagebloom has been running on MySQL 5.7 for some time now and it runs brilliantly - it's exceptionally responsive and provides great user experience. The performance of the underlying MySQL 7 has been great except... Clustered indexing: The double edged sword Part of MySQL's great read performance is due to an "under the hood" design feature that most software developers who use it are blissfully unaware of. In the automobile world it would be the equivalent of fuel injection or a turbo/super charger or in German - a Kompresser! These are features that can be added to the design of an engine to provide a significant boost in performance. For MySQL this feature is what is known as a "Clustered Index". The main concept of a clustered index is that the core data of each record is actually stored within the primary key index. Yes, you heard correctly - actual record data is embedded into the B-tree frames that make up the ind

With IP 4's limited range of public IP addresses and free IP 4 addresses becoming scarce it makes sense that the world should migrate over to IP 6 ASAP ... or should it? What's an IP address anyway? A bit of background for those who did not know that the internet predated the world wide web by a good two decades or more: IP addresses are kind of like  a physical street address. You write a physical address of a place anywhere in the world on the front of an envelope, put an appropriate stamp on it and then one or more postal services around the world will cooperate with each other to, hopefully, get your envelope to the "TO" address you specified. A public IP address identifies a "place" (e.g. a web server) on the internet where internet "data packets" can be sent. There's a lot of different protocols that can be used to send data across the internet but at the lowest levels they are all based on a simple principle: The internet is basically on

Occasionally you come up with the world's most unbreakable root password for a MySQL 8 installation and you get distracted before you record it somewhere.... and you remain distracted for 3 months. Then you return to the project where this database was needed and ... whoops! What was that totally awesome password? Here's how you can reset your root password. This was based on a page that had a similar instructions except none of them worked - lots of errors and incorrect names - like referring to mysql instead of mysqld when stopping the service. Here we go: All as root user: Create a file in /var/lib/mysql called mysql-pwd with the following contents: ALTER USER 'root'@'localhost' IDENTIFIED BY 'anotherPwd28^$94'; Shutdown mysql   systemctl stop mysqld Run MySQL executing the given init file under the mysql user   mysqld --init-file=/var/lib/mysql/mysql-pwd --user=mysql & Check the MySQL log to make sure no errors occurred:   vi /var/log/mysqld.log