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SQL

A collection of 180 issues

Teradata COALESCE Function: Purpose, Syntax, Alternative and Data Types

What is the purpose of the Teradata COALESCE function?COALESCE receives a list of scalars as arguments and returns the first value that is not NULL. If all scalars are NULL, then COALESCE returns NULL. What is the syntax of the Teradata COALESCE function?SELECT COALESCE(skalar1, skalar2, skalar3,...,skalarN)

Optimizing Teradata Joins: Tips to Reduce Resource Consumption

Unnecessary IO Elimination – Teradata View Optimization

Summary Today I will show you how to identify the source problem to tune the query's performance utilizing the unnecessary amount of IO, the UII indicator, and how the WHERE clause placed on a VIEW is evaluated. This case shows that the WHERE clause placed on VIEW for

Data Modeling and the Teradata FSLDM

Overview * What is A Data Model? * What are the Major Types of Data Models? * What is FS-LDM? * How is FS-LDM Implemented? Dimensional Modeling * Dimensional Modeling (DM) is a modeling technique in data warehousing, visually represented as a fact table surrounded by dimension tables. * Some of the terms commonly used in

Understanding Teradata Secure Zones: A Clear Explanation and Possible Use Cases

Teradata Secure Zones I've had a few conversations recently with different customers about the "Secure Zones" optional feature added in Teradata 15.10. There is a fair amount of misunderstanding about what this feature offers and does. This article aims to provide some clear information for

Teradata Sliding Window Merge Join: A Detailed Explanation

Teradata Show Table Proxy: Recreate Full DDL from DBC Tables and Views

A Teradata Show Table Proxy for Full DDL Recreation from DBC Throughout my recent development activities, an old desire became relevant again. It goes as follows: Can one write a query that recreates the entire DDL of a table out of dbc views or tables alone? Want more practical data

Teradata Physical Storage: Exploring Data Blocks and Storage Demographics

DISTINCT vs. GROUP BY: Understanding Performance Differences Based on Data Demographics in Teradata

Over the years, numerous debates have emerged concerning the superior performance of specific statements: SELECT <COLUMN> GROUP BY 1 or SELECT DISTINCT <COLUMN> Many personal experiences are often shared but tend to misattribute causality. People usually construct a single test scenario and extrapolate sweeping conclusions from

Teradata Historisation - Daily snapshot to change history

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