Analysis of data warehousing giant Teradata. Related subjects include:

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

August 19, 2012

In-database analytics — analytic glossary draft entry

This is a draft entry for the DBMS2 analytic glossary. Please comment with any ideas you have for its improvement!

Note: Words and phrases in italics will be linked to other entries when the glossary is complete.

“In-database analytics” is a catch-all term for analytic capabilities, beyond standard SQL, running on the same machine as and under the management of an analytic DBMS. These can run in one or both of two modes:

In-database analytics may offer great performance and scalability advantages versus the alternative of extracting data and having it be processed on a separate server. This is particularly likely to be the case in MPP (Massively Parallel Processing) analytic DBMS environments.

Examples of in-database analytics include:

Other common domains for in-database analytics include sessionization, time series analysis, and relationship analytics.

Notable products offering in-database analytics include:

August 19, 2012

Data warehouse appliance — analytic glossary draft entry

This is a draft entry for the DBMS2 analytic glossary. Please comment with any ideas you have for its improvement!

Note: Words and phrases in italics will be linked to other entries when the glossary is complete.

A data warehouse appliance is a combination of hardware and software that includes an analytic DBMS (DataBase Management System). However, some observers incorrectly apply the term “data warehouse appliance” to any analytic DBMS.

The paradigmatic vendors of data warehouse appliances are:

Further, vendors of analytic DBMS commonly offer — directly or through partnerships — optional data warehouse appliance configurations; examples include:

Oracle Exadata is sometimes regarded as a data warehouse appliance as well, despite not being solely focused on analytic use cases.

Data warehouse appliances inherit marketing claims from the category of analytic DBMS, such as: Read more

August 7, 2012

Notes on some basic database terminology

In a call Monday with a prominent company, I was told:

That, to put it mildly, is not accurate. So I shall try, yet again, to set the record straight.

In an industry where people often call a DBMS just a “database” — so that a database is something that manages a database! — one may wonder why I bother. Anyhow …

1. The products commonly known as Oracle, Exadata, DB2, Sybase, SQL Server, Teradata, Sybase IQ, Netezza, Vertica, Greenplum, Aster, Infobright, SAND, ParAccel, Exasol, Kognitio et al. all either are or incorporate relational database management systems, aka RDBMS or relational DBMS.

2. In principle, there can be difficulties in judging whether or not a DBMS is “relational”. In practice, those difficulties don’t arise — yet. Every significant DBMS still falls into one of two categories:

*I expect the distinction to get more confusing soon, at which point I’ll adopt terms more precise than “relational things” and “relational stuff”.

3. There are two chief kinds of relational DBMS: Read more

July 25, 2012

Thoughts on the next releases of Oracle and Exadata

A reporter asked me to speculate about the next releases of Oracle and Exadata. He and I agreed:

My answers mixed together thoughts on what Oracle should and will emphasize (which aren’t the same thing but hopefully bear some relationship to each other ;) ). They were (lightly edited):

July 12, 2012

How important is BI flexibility?

How flexible does business intelligence technology need to be? Should it allow fully flexible ad-hoc data analysis, or does that overwhelm users? Are they perhaps happier with simpler, more prescriptive analytic paths? My answer is a resounding “It depends”.

On the one hand, it’s clear that some users really care about business intelligence flexibility. They don’t want the “right” dimensional hierarchy, carefully worked out in advance. They don’t even want fixed drilldown paths smartly calculated on the fly, ala’ Endeca (which, after all, ultimately didn’t succeed). Rather, they want to be able to truly choose aggregations and roll-ups for themselves.

Supporting this view is the rise of in-memory business intelligence. For example:

But why would anybody pay up for the speed of in-memory BI? Analytic RDBMS offer blazing speed for broad ranges of queries. Parameterized reports let you do drilldowns in memory. So only if you need great flexibility do you need to keep a whole analytic data set permanently in RAM.

Read more

June 26, 2012

Teradata SQL-H, using HCatalog

When I grumbled about the conference-related rush of Hadoop announcements, one example of many was Teradata Aster’s SQL-H. Still, it’s an interesting idea, and a good hook for my first shot at writing about HCatalog. Indeed, other than the Talend integration bundled into Hortonworks’ HDP 1, Teradata SQL-H is the first real use of HCatalog I’m aware of.

The Teradata SQL-H idea is:

At least in theory, Teradata SQL-H lets you use a full set of analytic tools against your Hadoop data, with little limitation except price and/or performance. Teradata thinks the performance of all this can be much better than if you just use Hadoop (35X was mentioned in one particularly favorable example), but perhaps much worse than if you just copy/extract the data to an Aster cluster in the first place.

So what might the use cases be for something like SQL-H? Offhand, I’d say:

By way of contrast, the whole thing makes less sense for dashboarding kinds of uses, unless the dashboard users are very patient when they want to drill down.

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