327 technical articles on Teradata, Snowflake, Databricks, SQL tuning and data warehouse architecture — written from production experience, not vendor decks.
Introduction to the Teradata Sliding Window Merge Join DWH Pro thoroughly analyzes the Teradata sliding window merge join, which has limited available information. Our extensive research provides valuable insights into this process. To understand the Teradata sliding window merge join, we must first review the join algorithms used in the conventional merge join. This will …
As always, when something comes to the attention of a larger number of people, some embrace it, some frown. We were asked to dissociate the name of this website from the term Teradata. We do so to avoid any future misunderstanding, irrespective of any admission of fault. You will find us at www.dwhpro.com from now …
Compatibility note: this downloadable generator is retained as a historical example, not a supported replacement for SHOW TABLE. On Teradata Database 20.00.28.81 it returned no DDL for a simple existing test table, while SHOW TABLE returned the definition. Use SHOW TABLE database_name.table_name; for the current table DDL and verify dependent objects separately before recreation. A …
This is a conceptual explanation with historical implementation examples. Logical cylinders and sectors do not imply mechanical disk geometry, and exact packing thresholds must be checked for the target release. It is not an instruction to run storage-maintenance utilities on a live system. Introduction to Teradata Physical Storage In the second part of this series …
Over the years, numerous debates have emerged concerning the superior performance of specific statements: Many personal experiences are often shared but tend to misattribute causality. People usually construct a single test scenario and extrapolate sweeping conclusions from it. The answer depends on semantics, data demographics and the optimizer plan. The validity of these statements hinges …
Introduction to Teradata Data Types and Data Modeling Suppose you work in a well-organized environment where diligence and discipline prevail and significant effort is put into designing things right in the beginning. In that case, the following post might seem outlandish to you. Else, read on. In a more “experimental” table design landscape, you will …
For various reasons, we may need to switch our Teradata historisation from snapshot tables to a start date/end date logic table, which I usually call a change history, as only changes trigger a historisation. A principal motivation for such a move away from a daily snapshot table could be space restrictions. The former full conversion …
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