Analysis and discussion of the open source data management project Cassandra. Related subjects include:

March 27, 2012

DataStax Enterprise and Cassandra revisited

My last post about DataStax Enterprise and Cassandra didn’t go so well. As follow-up, I chatted for two hours with Rick Branson and Billy Bosworth of DataStax. Hopefully I can do better this time around.

For starters, let me say there are three kinds of data management nodes in DataStax Enterprise:

Cassandra, Solr, Lucene, and Hadoop are all Apache projects.

If we look at this from the standpoint of DML (Data Manipulation Language) and data access APIs:

In addition, it is sometimes recommended that you use “in-entity caching”, where an entire data structure (e.g. in JSON) winds up in a single Cassandra column.

The two main ways to get direct SQL* access to data in DataStax Enterprise are:

*or very SQL-like, depending on how you view things

Before going further, let’s recall some Cassandra basics: Read more

March 21, 2012

DataStax Enterprise 2.0

Edit: Multiple errors in the post below have been corrected in a follow-on post about DataStax Enterprise and Cassandra.

My client DataStax is announcing DataStax Enterprise 2.0. The big point of the release is that there’s a bunch of stuff integrated together, including at least:

DataStax stresses that all this runs on the same cluster, with the same administrative tools and so on. For example, on a single cluster:

Read more

February 1, 2012

Couchbase update

I checked in with James Phillips for a Couchbase update, and I understand better what’s going on. In particular:

Read more

January 8, 2012

Big data terminology and positioning

Recently, I observed that Big Data terminology is seriously broken. It is reasonable to reduce the subject to two quasi-dimensions:

given that

But the conflation should stop there.

*Low-volume/high-velocity problems are commonly referred to as “event processing” and/or “streaming”.

When people claim that bigness and structure are the same issue, they oversimplify into mush. So I think we need four pieces of terminology, reflective of a 2×2 matrix of possibilities. For want of better alternatives, my suggestions are:

Read more

October 23, 2011

NoSQL notes

Last week I visited with James Phillips of Couchbase, Max Schireson and Eliot Horowitz of 10gen, and Todd Lipcon, Eric Sammer, and Omer Trajman of Cloudera. I guess it’s time for a round-up NoSQL post. :)

Views of the NoSQL market horse race are reasonably consistent, with perhaps some elements of “Where you stand depends upon where you sit.”

Read more

October 2, 2011

Defining NoSQL

A reporter tweeted:  “Is there a simple plain English definition for NoSQL?” After reminding him of my cynical yet accurate Third Law of Commercial Semantics, I gave it a serious try, and came up with the following. More precisely, I tweeted the bolded parts of what’s below; the rest is commentary added for this post.

NoSQL is most easily defined by what it excludes: SQL, joins, strong analytic alternatives to those, and some forms of database integrity. If you leave all four out, and you have a strong scale-out story, you’re in the NoSQL mainstream. Read more

September 22, 2011

DataStax pivots back to its original strategy

The DataStax and Cassandra stories are somewhat confusing. Unfortunately, DataStax chose to clarify them in what has turned out to be a crazy news week. I’m going to use this post just to report on the status of the DataStax product line, without going into any analysis beyond that.

Read more

August 13, 2011

Couchbase business update

I decided I needed some Couchbase drilldown, on business and technology alike, so I had solid chats with both CEO Bob Wiederhold and Chief Architect Dustin Sallings. Pretty much everything I wrote at the time Membase and CouchOne merged to form Couchbase (the company) still holds up. But I have more detail now. ;)

Context for any comments on customer traction includes:

That said,

Membase sales are concentrated in five kinds of internet-centric companies, which in declining order are: Read more

July 15, 2011

Soundbites: the Facebook/MySQL/NoSQL/VoltDB/Stonebraker flap, continued

As a follow-up to the latest Stonebraker kerfuffle, Derrick Harris asked me a bunch of smart followup questions. My responses and afterthoughts include:

Continuing with that discussion of DBMS alternatives:

And while we’re at it — going schema-free often makes a whole lot of sense. I need to write much more about the point, but for now let’s just say that I look favorably on the Big Four schema-free/NoSQL options of MongoDB, Couchbase, HBase, and Cassandra.

May 15, 2011

What to do about “unstructured data”

We hear much these days about unstructured or semi-structured (as opposed to) structured data. Those are misnomers, however, for at least two reasons. First, it’s not really the data that people think is un-, semi-, or fully structured; it’s databases.* Relational databases are highly structured, but the data within them is unstructured — just lists of numbers or character strings, whose only significance derives from the structure that the database imposes.

*Here I’m using the term “database” literally, rather than as a concise synonym for “database management system”. But see below.

Second, a more accurate distinction is not whether a database has one structure or none – it’s whether a database has one structure or many. The easiest way to see this is for databases that have clearly-defined schemas. A relational database has one schema (even if it is just the union of various unrelated sub-schemas); an XML database, however, can have as many schemas as it contains documents.

One small terminological problem is easily handled, namely that people don’t talk about true databases very often, at least when they’re discussing generalities; rather, they talk about data and DBMS.* So let’s talk of DBMS being “structured” singly or multiply or whatever, just as the databases they’re designed to manage are.

*And they refer to the DBMS as “databases,” because they don’t have much other use for the word.

All that said — I think that single vs. multiple database structures isn’t a bright-line binary distinction; rather, it’s a spectrum. For example:  Read more

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