Who Cares

Who Cares

CISCO VPN Client dropping with “Reason 422: Lost contact with the security gateway”

Writing this out of embarrassment but hopefully it will help somebody else if they have the same issue with the CISCO VPN Client or similar. When at my girlfriends I VPN over her WiFi into my client, that’s always worked, but, last Thurs/Friday I started getting issues with the VPN dropping out after just a […]

How Hekaton (XTP) achieves Durability for “Memory Optimised” Tables

“Memory Optimised” tables reside entirely in memory, the operations INSERT, UPDATE and DELETE as well as SELECT are all significantly quicker, but just how is it possible to achieve durability with memory optimised tables while still achieving the significantly higher throughput? Like traditional on-storage tables durability is achieved once the data has been written and hardened off […]

Changing In-Memory Table definition without down time

One of the restrictions of a “memory optimised” table is that you cannot modify its definition once created. You may find that once your table has been in use for a period of time it may be apparent you don’t need one of the Hash indexes for example, or perhaps you made a hash (pardon the […]

Maximum IOPS for a 10K or 15K SAS Hard Disk Drive is not 170!

At times, mmm quite often now actually (perhaps it’s because I’m getting older and more grumpy) the industry I’m part of really makes me embarrassed, all too often folk just quote things they’ve seen on Wikipedia or via word of mouth without even a basic knowledge of the “fact” they are quoting – a “fact” […]

The inescapable problem of Latency within Data-based systems

It’s long troubled me people touting Real-Time Business Intelligence when its physically impossible to achieve true real-time; I’ve jotted down some thoughts in an attempt to bring order and better understanding to the reality of “Real-Time” – hopefully the post will help you in dealing with vendors, giving you some insight into what questions to […]

SQL Server Hekaton (XTP) in-memory tables: Choosing the correct BUCKET_COUNT for a Hash Index

In this post I cover off how to choose the correct number for the BUCKET_COUNT and how you go about that, also, how to monitor and change the bucket_count. The general approach is that you set the BUCKET_COUNT to the number of unique values there will be given just the columns on your hash index (see […]

SQL Server Hekaton (XTP) in-memory Tables: Range Indexes and Row Chains

Hash and Range indexes both involve row chains, if you haven’t already read my post on Understanding the row chains of Hash Indexes I’d suggest you do before continuing with this post which essentially is a continuation of it and assumes you know the basics of row chains already. A range index is implemented using the […]

SQL Server Hekaton In-memory tables: Understanding the Row Chains of Hash Indexes

Having a good understanding of how the hashing and row chains work will go a long way in helping you design for performance and diagnose performance and resource issues you may get once live. This post covers off some of the basics and hopefully will give you a working insight. We’ll start with a Hash […]

Hekaton In-Memory Tables: HASH Indexes

The purpose of this post is to help you understand the new HASH indexing in SQL Server 2014 in-memory tables feature (project Hekaton). As ever, it’s actually quite a big topic so I’ll cover aspects in multiple posts (I’ll pop back here and update the links once complete)… Post 1 – How the Hash Index works Post […]