Join performance in MongoDB 3.2 using $lookup

One of the key tenants of MongoDB schema design is to account for the absence of server-side joins.  Data is joined all the time inside of application code of course, but traditionally there’s been no way to perform joins within the server itself. 

This changed in 3.2 with the introduction of the $lookup operator within the aggregation framework.  $lookup performs the equivalent of a left outer join – eg: it retrieves (more...)

Good bye Quest!

You may have read that Francisco Partners and Elliott Management have entered into an agreement to  Acquire the Dell Software Group – largely composed of the Quest software company bought from Dell in 2012 .   I’ve worked at Quest since 1998, but alas I will not be participating in this next stage of the Quest journey.
Although the timing of the announcement was influenced by the logistics of this sale, it is actually a (more...)

Next Generation Databases

dbtngMy latest book Next Generation Databases is now available to purchase!   You can buy it from Amazon here, or directly from Apress here.  The e-book versions are not quite ready but if you prefer the print version you’re good to go.

I wrote this book as an attempt to share what I’ve learned about non-relational databases in the last decade and position these in the context of the relational database landscape that (more...)

Blockchain and databases of the future

You would have to have been living under a rock for the past few years not to have heard of Bitcoin.    Bitcoin is an electronic cryptocurrency which can be used like cash in many web transactions.  At time of writing there are about 15 million Bitcoins in circulation, trading at approximately $USD 360 each for a total value of about $USD 5.3 billion.

Bitcoin combines peer-to-peer technology and public key cryptography.  (more...)

Vector clocks


Once of the concepts I found difficult initially when looking at non-relational systems is the concept of the vector clock.  Some databases – like Cassandra - use timestamps to work out which is the “latest” transaction. If there are two conflicting modifications to a column value, the one with the highest timestamp will be considered the most recent and the most correct.

Other Dynamo systems use a more complex mechanism known as a (more...)

Exploring CouchBase N1QL

Couchbase recently announced Non-first Normal Form Query Language (N1QL) – pronounced “Nickel” – a virtually complete SQL language implementation for use with document databases, and implemented within the Couchbase server 4.0.

I recently took a quick look. 

Most of the examples use the sample films documents shown below (this is the same sample data we created for MongoDB in this post):

2015-10-05_16-43-02 n1ql

N1QL allows us to perform basic queries to retrieve selected documents (more...)

On my way to Collaborate 2015

As I write this I’m at 35,000 ft (or so) on my way to yet another Collaborate.  This year I’ll be presenting two sessions and participating in one panel:

963: Writing to Lead
Monday, April 13  |  Banyan E, South Convention Center, Level 2
10:30 a.m. – 11:30 a.m.
Jonathan Gennick will be moderating a panel including myself, Bobby Curtis, Charles Kim, Darl Kuln and Michael Rosenblum.  We’ll be talking about how writing (more...)

Sakila sample schema in MongoDB

I wanted to do some experimenting with MongoDB, but I wasn’t really happy with any of the sample data I could find in the web.  So I decided that I would translate the MySQL “Sakila” schema into MongoDB collections as part of the learning process.   

For those that don’t know, Sakila is a MySQL sample schema that was published about 8 years ago.  It’s based on a DVD rental system.   OK, (more...)

Best practices for accessing Oracle from scala using JDBC

I’ve been looking for an excuse to muck about with scala for a while now.  So I thought i’d do a post similar to those I’ve done the past for .NET, python, perl and R.  Best practices for Java were included in my book Oracle Performance Survival Guide (but I’d be more than happy to post them if anyone asks).

One of the great things about scala is that it runs (more...)

Using SSD for a temp tablespace on Exadata

I seem to be getting a lot of surprising performance results lately on our X-2 quarter rack Exadata system, which is good – the result you don’t expect is the one that teaches you something new.

This time, I was looking at using a temporary tablespace based on flash disks (more...)