In my previous post “Why GUID primary keys are a database’s worst nightmare” I spoke about some of downsides to using GUID primary keys. In this post I’m going to focus more specifically on the .NET Framework’s implementation of System.Guid. I have a few complaints about this class, let’s cover them… 1. Guid.ToByteArray() This, IMHO, [...]
When you ask most people why using a GUID column for a primary key in a database might be slower than auto-incremented number the answer your likely to get is usually along these lines: “Guids are 16 bytes, and integers are only 4 bytes.” While this information is technically accurate, it is completely the wrong [...]
Ok I swear this is the last B+Tree chart, graph, or metric I’ll post… at least for a while. I wanted to hit new limits so I fired up 6 threads on my six-core and let them rip… After three hours I finally stopped the run to look at the results. Each of the six [...]
Oct 122011
Test Overview The benchmark results below are from a single thread on a process with the thread-affinity set except two. The BPlusTree(Threaded) and obviously MySql were not constrained. All data used during the test was generated before the test ran. The number displayed in the logarithmic horizontal axis is the average number of operations completed [...]
Oct 122011
Before I go much farther talking about the BPlusTree I want to address one thing. Does the BPlusTree support ACID operations? (definitions below from wikipedia) Atomicity Atomicity requires that database modifications must follow an “all or nothing” rule. Each transaction is said to be atomic. If one part of the transaction fails, the entire transaction [...]
Apr 262011
Cont’d from Building a database in C# – Part 2 Caching and persistence seem to go hand-in-hand for this adventure. With the cost of serialization and IO it’s just not possible to get anything to perform well without a little caching. The questions I had around caching is really more along the lines of “how” [...]
Mar 232011
Cont’d from Building a database in C# – Part 1 So with the B+ tree semantics out of the way it was time to start looking at what was missing. Obviously it was all in memory and not yet on disk, and once it is on disk I’ll certainly need to cache. Yet there was [...]
Mar 142011
Ok, so for the last week or two I’ve been off on an adventure of sorts with persistent media data structures. At first I was like “Surely a good solution exists?” this isn’t a new problem. Unfortunately I was unable to locate any solutions that were open source (non-GPL) and written entirely in managed code. [...]