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3 weeks ago

Think about the priority part of workload management for a minute.

The settings that the administrator makes when defining priorities for different workloads are on the surface--things like workload allocation percentages and access level assignments.  They are easy to see.  Below the surface are “global weights”, which starting in Teradata Database 14.10 indicate to you the actual percentage of platform resources your workload will receive, based on its allocation.

But they do more than translate your settings to an expected resource share.  Global weights are used by the database to order the queues for several internal entities.  For example, the AMP worker task (AWT) message queue is now ordered by global weight in SLES 11. 

So it’s time you spent a few minutes taking a closer look at what global weights are, how the SLES 11 priority scheduler calculates them, and how you can influence them.

3 weeks ago

The amount of data that is now available for analysis is growing at an exponential rate.  As the hardware to capture the data becomes cheaper, faster and omnipresent, the amount of data collected for analysis is becoming beyond the scope of the current analytical staffs to examine it all. 

12 Feb 2015

I/O Token Allocations (IOTAs) are used in Teradata Database 14.10 with SLES 11 systems to enforce the I/O side of Workload Management Capacity on Demand (WM COD) and other SLES 11 hard limits.

This posting describes what IOTAs are and what role they play in enforcing I/O limits with WM COD.   In addition, and maybe more importantly, we’ll be looking at how IOTA numbers being reported in ResUsage can help you assess the I/O utilization of your workloads, and the I/O utilization of your entire platform, whether or not you have WM COD enabled.

22 Jan 2015

The Teradata JDBC Driver Engineering team receives a lot of questions about what happens when a JDBC connection is created. Let's clarify the concepts Laddered Concurrent Connect (LCC) versus COP Discovery versus logon, and review what the Teradata JDBC Driver does to create a JDBC connection.


First, some definitions...

"COP" stands for Communications Processor, and is a term originating from Teradata's earliest database appliances in the 1980s. In modern usage, a "COP" is a Teradata Database node that is running a Teradata Database Gateway process.

19 Jan 2015

As of Teradata Database 14.10.05 and 15.00.03, a simplified approach to determining which workload will support session management and parsing has been adopted  This posting describes this more straightforward approach which will be used starting in these 14.10 and 15.0 releases, and going forward in all future releases.

An earlier posting titled:  “A Closer Look at How to Setup a Parsing-Only Workload”  explains how session and parsing workload assignment takes place prior to this more simplified approach.  If you are on an earlier release, please see that posting from December 2014.

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

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.