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21 Jan 2014

Many experienced SQL and procedure developers use SQL functions to perform common tasks and simplify their code narratives. The function concept is a good programming technique, but adopting it literally in a Set SQL statement may force the statement to execute as a serial process; that is, it can make parallel processing impossible.  This is one reason Teradata SQL does not allow functions to access tables.

20 Jan 2014

Most Teradata systems support different processing windows, each which has a somewhat different set of business priorities.  From 8 AM to 12 noon the most important work may be the Dashboard application queries.  But from 12 noon to 6 PM it could be the ad hoc business users.   At night maybe it’s the batch loads and reporting.   Planned Environments function within the TASM state matrix to support the ability to automatically manage changes to workload management setup during those different windows of time.

17 Dec 2013
Besides collecting statistics on your columns on your Teradata database, the compressing of the data to save disk space is a very important maintaining task. So why not connect these two tasks? The idea is to extract the values for the multi value compression of the columns out of the collected statistics.
 
16 Dec 2013

The following batches 5 rows of data, 2 of them with errors. The JDBC FastLoad PreparedStatement.executeBatch attempts to INSERT the batched rows into a database table but throws a JDBC SQLException. Here is how to capture the chain of JDBC FastLoad SQLException messages and stack trace from JDBC FastLoad PreparedStatement.executeBatch and the chain of JDBC FastLoad SQLWarning messages and stack trace from JDBC FastLoad Connection.rollback:

13 Dec 2013

The following batches 5 rows of data, 2 of them with errors. The JDBC PreparedStatement.executeBatch attempts to INSERT the batched rows into a database table but throws a JDBC SQLException. Here is how to capture the chain of JDBC SQLException error messages and stack trace:

06 Dec 2013

JDBC Connection parameter LOG=DEBUG prints error, timing, informational, and debug messages to Java System.out. The following shows how the messages can be captured with R.

04 Dec 2013

The implementation of dbConnect in RJDBC version 0.1-5 thru 0.2-2 (http://www.rforge.net/RJDBC/news.html) erroneously creates two (duplicate) connections. The RJDBC version currently in use can be obtained by entering citation("RJDBC") at the R command prompt.

03 Dec 2013

The following shows how to select rows from a database table using JDBC FastExport, which only works with JDBC PreparedStatement.

02 Dec 2013

Everyone with a Teradata Database collects statistics.  No way around it.  Good query plans rely on it, and we’ve all gotten used to it.

But starting in Teradata Database 14.10 there’s some big changes.  Numerous enhancements to the optimizer, some important database changes, a new set of APIs, an added data dictionary table, and a brand new Viewpoint portlet all combine together to produce the Automated Statistics (AutoStats) feature.  Used fully, AutoStats can identify statistics the optimizer looked for and found missing, flag unused statistics that you no longer need to collect on, prioritize and execute the stats collection statements, and organize/run your statistics collection jobs in the most efficient way possible.

There’s a lot going on and a lot of choices involved.  So what’s the easiest way to start getting familiar with AutoStats?   And what’s required with the new DBQL logging options?  If you like to build up confidence in a new feature at your own pace, this blog posting offers a few simple steps designed to introduce you to key features and benefits AutoStats.  

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