Teradata

Analysis of data warehousing giant Teradata. Related subjects include:

April 15, 2013

Teradata SQL-H

As vendors so often do, Teradata has caused itself some naming confusion. SQL-H was introduced as a facility of Teradata Aster, to complement SQL-MR.* But while SQL-MR is in essence a set of SQL extensions, SQL-H is not. Rather, SQL-H is a transparency interface that makes Hadoop data responsive to the same code that would work on Teradata Aster …

*Speaking of confusion — Teradata Aster seems to use the spellings SQL/MR and SQL-MR interchangeably.

… except that now there’s also a SQL-H for regular Teradata systems as well. While it has the same general features and benefits as SQL-H for Teradata Aster, the details are different, since the underlying systems are.

I hope that’s clear. :)

March 18, 2013

DBMS development and other subjects

The cardinal rules of DBMS development

Rule 1: Developing a good DBMS requires 5-7 years and tens of millions of dollars.

That’s if things go extremely well.

Rule 2: You aren’t an exception to Rule 1. 

In particular:

DBMS with Hadoop underpinnings …

… aren’t exceptions to the cardinal rules of DBMS development. That applies to Impala (Cloudera), Stinger (Hortonworks), and Hadapt, among others. Fortunately, the relevant vendors seem to be well aware of this fact. Read more

February 6, 2013

Key questions when selecting an analytic RDBMS

I recently complained that the Gartner Magic Quadrant for Data Warehouse DBMS conflates many use cases into one set of rankings. So perhaps now would be a good time to offer some thoughts on how to tell use cases apart. Assuming you know that you really want to manage your analytic database with a relational DBMS, the first questions you ask yourself could be:

Let’s drill down. Read more

February 5, 2013

Comments on Gartner’s 2012 Magic Quadrant for Data Warehouse Database Management Systems — evaluations

To my taste, the most glaring mis-rankings in the 2012/2013 Gartner Magic Quadrant for Data Warehouse Database Management are that it is too positive on Kognitio and too negative on Infobright. Secondarily, it is too negative on HP Vertica, and too positive on ParAccel and Actian/VectorWise. So let’s consider those vendors first.

Gartner seems confused about Kognitio’s products and history alike.

Gartner is correct, however, to note that Kognitio doesn’t sell much stuff overall.

* non-existent

In the cases of HP Vertica, Infobright, ParAccel, and Actian/VectorWise, the 2012 Gartner Magic Quadrant for Data Warehouse Database Management’s facts are fairly accurate, but I dispute Gartner’s evaluation. When it comes to Vertica: Read more

January 26, 2013

Editing code is easier than writing it

I’ve hacked both the PHP and CSS that drive this website. But if I had to write PHP or CSS from scratch, I literally wouldn’t know how to begin.

Something similar, I suspect, is broadly true of “business analysts.” I don’t know how somebody can be a competent business analyst without being able to generate, read, and edit SQL. (Or some comparable language; e.g., there surely are business analysts who only know MDX.) I would hope they could write basic SELECT statements as well.

But does that mean business analysts are comfortable with the fancy-schmantzy extended SQL that the analytic platform vendors offer them? I would assume that many are but many others are not. And thus I advised such a vendor recently to offer sample code, and lots of it — dozens or hundreds of isolated SQL statements, each of which does a specific task.* A business analyst could reasonably be expected to edit any of those to point them his own actual databases, even though he can’t necessarily be expected to easily write such statements from scratch.  Read more

October 17, 2012

Notes on analytic hardware

I took the opportunity of Teradata’s Aster/Hadoop appliance announcement to catch up with Teradata hardware chief Carson Schmidt. I love talking with Carson, about both general design philosophy and his views on specific hardware component technologies.

From a hardware-requirements standpoint, Carson seems to view Aster and Hadoop as more similar to each other than either is to, say, a Teradata Active Data Warehouse. In particular, for Aster and Hadoop:

The most obvious implication is differences in the choice of parts, and of their ratio. Also, in the new Aster/Hadoop appliance, Carson is content to skate by with RAID 5 rather than RAID 1.

I think Carson’s views about flash memory can be reasonably summarized as: Read more

October 17, 2012

Hadoop/RDBMS integration: Aster SQL-H and Hadapt

Two of the more interesting approaches for integrating Hadoop and MapReduce with relational DBMS come from my clients at Teradata Aster (via SQL/MR and SQL-H) and Hadapt. In both cases, the story starts:

Of course, there are plenty of differences. Those start: Read more

October 17, 2012

The Teradata Aster Big Analytics Aster/Hadoop appliance

My clients at Teradata are introducing a mix-em/match-em Aster/Hadoop box, officially called the Teradata Aster Big Analytics Appliance. Basics include:

My views on the Teradata Aster Big Analytics Appliance start: Read more

September 27, 2012

Hoping for true columnar storage in Oracle12c

I was asked to clarify one of my July comments on Oracle12c,

I wonder whether Oracle will finally introduce a true columnar storage option, a year behind Teradata. That would be the obvious enhancement on the data warehousing side, if they can pull it off. If they can’t, it’s a damning commentary on the core Oracle codebase.

by somebody smart who however seemed to have half-forgotten my post comparing (hybrid) columnar compression to (hybrid) columnar storage.

In simplest terms:

August 26, 2012

How immediate consistency works

This post started as a minor paragraph in another one I’m drafting. But it grew. Please also see the comment thread below.

Increasingly many data management systems store data in a cluster, putting several copies of data — i.e. “replicas” — onto different nodes, for safety and reliable accessibility. (The number of copies is called the “replication factor”.) But how do they know that the different copies of the data really have the same values? It seems there are three main approaches to immediate consistency, which may be called:

I shall explain.

Two-phase commit has been around for decades. Its core idea is:

Unless a piece of the system malfunctions at exactly the wrong time, you’ll get your consistent write. And if there indeed is an unfortunate glitch — well, that’s what recovery is for.

But 2PC has a flaw: If a node is inaccessible or down, then the write is blocked, even if other parts of the system were able to accept the data safely. So the NoSQL world sometimes chooses RYW consistency, which in essence is a loose form of 2PC: Read more

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