Subscribe to Terdata Developer Exchange - RSS feed for all blogs Latest blog posts
14 Jan 2015

There is a demand to have a functionality similar to the industry standard SHA256 hash function to condense RDBMs table content to a single value which is changing completely in case a single bit changes in multi million or billion row tables.

31 Dec 2014

The theme of this blog is an examination of forces that would disrupt existing data warehouse implementations.  I categorize these as either long tail or black swan events.

10 Dec 2014

Note:  This content only applies to releases earlier than Teradata Database 14.10.05.  If you are on Teradata Database 14.10.05 or later releases, please look at the more recent posting titled:  A New Simplified Approach to Parsing Workload Selection.

When you think about priorities, you probably focus your attention on AMP work.  Whether you are using Teradata Active System Management (TASM) or Teradata Integrated Workload Management (TIWM), AMP work performed by requests are typically spread across different workloads, with their priorities based on the importance of the work to the business and how long you expect the work to run.

Parsing engine work on behalf of a query runs within a workload as well.  Work performed on the parsing engine is typically very quick and requires very few resources.  So why not run some, or all, of your parsing activity in a very high priority workload where it may be able to complete sooner when your system is busy,  just as you do with your short, critical AMP work?  This posting will explain how parsing priority is determined, and will illustrate the steps involved in increasing parsing priority.

14 Nov 2014

Beginning with Teradata Database 14.0 and Teradata JDBC Driver, the Client Attributes feature records a variety of information about the client system and client software in the system tables DBC.SessionTbl and DBC.EventLog.

The Client Attributes are recorded at session logon time. Subsequently, the system views DBC.SessionInfoV and DBC.LogOnOffV can be queried to obtain information about the client system and client software on a per-session basis.

09 Nov 2014

Unstructured data can be dealt with effortlessly in Teradata. Regular expression has been around for many years in software fields. With the advent of Big data, hadoop, NO SQL, columnar, graph database, document  databases the usage of Regex is becoming more and more increasingly popular. The example highlighted below is just a tip of an iceberg of usage. There are umpteen features that can be incorporated into the databases.

02 Oct 2014

The accuracy of sample statistics has been greatly improved over the last Teradata releases. So I usually try to use sample stats on most of the big tables and I found them to be reliable on many columns, not only the officially recommended unique or nearly-unique columns, e.g. on DATEs.

But there is a specific scenario when sample stats result in worst case optimizer plans:

24 Sep 2014

During my first coding class, after the obligatory “Hello, World,” my assignment was to find the least cost path in a matrix of values (linear programming).  The computer took some time to crunch the data to come to a solution.  Now, this is an app on your phone.  

11 Sep 2014

Statistical information is vital for the optimizer when it builds query plans. But collecting statistics can involve time and resources. By understanding and combining several different statistics gathering techniques, users of Teradata can find the correct balance between good query plans and the time required to ensure adequate statistical information is always available.

This recently-updated compilation of statistics collection recommendations are intended for sites that are on any of the Teradata Database 14.10, 15.0, or 15.10 software release levels. Some of these recommendations apply to releases earlier than Teradata Database 14.10 and some rely on new features available starting in Teradata Database 14.10.  Statistics collection functionality in the Teradata Database works the same in 14.10, 15.0 and 15.10 releases.

For greater detail on collecting statistics for Teradata Database 14.10, see the orange book titled:  Teradata Database 14.10 Statistics Enhancements by Rama Krishna Korlapati.

Contributors: Carrie Ballinger, Rama Krishna Korlapati, Paul Sinclair, September 11, 2014

31 Jul 2014

Teradata has great perfomance in batch processing. As a typical OLAP system, Tereadata can't peform as well as OLTP in high concurrency real-time application. I wrote an open source framework - cheetah, which tries to work with Teradata together to provide better application experience cross batch and real-time requiements.

31 Jul 2014

How does TASM enforce rules such as classification and workload exceptions against User Defined Functions?  What about table functions and table operators, some of which do their work outside of Teradata?  How far can you rely on TASM classifications using estimated processing time in these cases?  Will there be accurate resource usage numbers reported to support workload exceptions on CPU or I/O?

These are some of the questions that need answering if you are extending the use of simple or more complex user-defined functions on your platform.