The Pitfalls of Teradata SELECT * Queries

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Introduction In a row-oriented database engine like Teradata, data is organized and stored in units called data blocks. Each data block features a fixed header and accommodates multiple rows. Every row consists of a record header followed by its corresponding columns. When a database retrieves and stores a data block in the cache, it accesses …

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Improving Stored Procedure Performance with Teradata MAPS Architecture

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Occasionally, it is necessary to utilize a cursor within a stored procedure to execute specific functionality. I recently encountered a stored procedure that contained a loop with multiple INSERT statements executed through a cursor. This particular cursor was designed to process only a limited number of rows. Despite this, the stored procedure took up to …

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Filter efficiently with Teradata NOS

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Teradata NOS facilitates querying data in an S3 object store with ease. To attain maximum performance, partitioning external data is crucial for efficient reading. This article outlines the key considerations for optimal efficiency when reading data from the object store. To begin, we must establish S3 access by obtaining an AUTHORIZATION object. In this instance, …

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Teradata TD_WhichMax and TD_WhichMin Functions: A SQL Solution for Finding Min/Max Value of a Column with Low Resource Consumption

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What is the Teradata TD_WhichMax Function? Teradata releases new SQL features with each update, providing enhanced functionality and improved performance with reduced resource usage. We will examine the Teradata TD_WhichMax and TD_WhichMin functions and explore their potential benefits. These functions retrieve the minimum or maximum value of a column and are commonly utilized in SQL …

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Maximizing Performance and Space Savings: Teradata Compression Techniques

tune4

Introduction to Teradata Compression Note: Teradata Block Level Compression is now permanently enabled and cannot be turned off. Nonetheless, this article remains useful for current Teradata systems utilizing block-level compression. It demonstrates the continued advantages of multi-value compression (Teradata MVC). With Teradata’s introduction of block-level compression, the utilization of multi-value compression at various Teradata sites …

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Comparing Index Types of SQL Server and Teradata: Clustered vs Row Partitioning, Non-clustered vs NUSI, USI, Join Index, and More

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This article compares the index types in SQL Server and Teradata. It can benefit those transitioning between the two platforms to understand their distinctions and overlaps, despite their different architectures. Clustered Index vs Teradata Row Partitioning The SQL Server’s clustered index arranges table rows in a specific physical order, making it ideal for range-based queries. …

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How the Number of Rows per Data Block Affects Teradata NUSI Selectivity: A Case Study

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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 qualifying rows that make a NUSI …

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