Roland Wenzlofsky
How the Number of Rows per Data Block Affects Teradata NUSI Selectivity: A Case Study
Teradata NUSI Selectivity and Data-Block Density
The goal of this article is to show how the number of rows per base-table data block impacts the selectivity threshold for Non-Unique Secondary Indexes (NUSI) in Teradata.
Understanding this correlation is critical when analyzing query plans and tuning indexing strategies.
The number of
Teradata Index Selection: Factors to Consider
The Teradata Tutorial to support the selection of indexes
How much space does the Teradata index occupy?An index can take up surprisingly much space, especially if the Teradata system does not automatically apply Block Level Compression to the index. MANY TIMES, a NUSI can take up the base table&
Understanding Teradata Statistics Histograms: How the Optimizer Estimates Cardinality for WHERE Conditions
Teradata Statistics Histograms - A Short Introduction
Many are familiar with the Optimizer's statistical confidence levels. I was recently surprised to discover that a "high confidence" rating does not guarantee a fully accurate estimation (provided the statistics collected are not stale). While I remain hopeful that
Hadoop and Teradata Data Warehousing: A Comparison and Integration Perspective
Hadoop is a buzzword in the world of big data, but its actual value can be concealed by the hype. This article compares Teradata and Hadoop Data Warehousing, highlighting the advantages of leveraging Hadoop's scalability and preprocessing capabilities to improve Teradata's performance. However, the
A Teradata HASHROW Table Difference Screening Test
Layer and Preparatory Table Strategies
Teradata Data Type Considerations
Introduction to Teradata Data Types
Further Data Type considerations require occasional attention to additional issues.
Happenstance Nullability
Strive for nullability settings that adhere to the data model and are consistent throughout all tables. Allowing mandatory columns to be left open for null entries incurs costs for both storage and optimization.
Teradata - Merging two change history tables
Have you encountered a poorly designed physical data model where object columns are distributed randomly across tables, and you wish to unify them in their rightful place?
Merging non-historical tables is simple, but the process becomes more complex when historization is applied to at least one of the tables.
Change
Collect Statistics in Teradata - Evaluation
Collect Statistics in Teradata - The Evaluation
After collecting every combination considered necessary and helpful, you can check the result of the collected statistics on a table by looking at
* the time it took to collect and the then prevailing circumstances
* the collection results
Consider the lengthier collection time when