NUSI Archives - Page 2 Of 4 -

Optimizing Teradata Performance through Statistics and Primary Index Selection

04/11/202605/03/2023 by Roland Wenzlofsky

1. Statistics In Teradata, understanding and managing statistics is essential for optimizing database performance. Statistics provide the optimizer with precise data about stored information, allowing for well-informed decisions when handling queries. This article will explore the significance of statistics in Teradata, their effect on query performance, and recommended methods for upkeep. The Role of Statistics …

Teradata MERGE INTO vs. UPDATE: Performance Comparison and Limitations

04/11/202605/02/2023 by Roland Wenzlofsky

Teradata MERGE INTO vs. UPDATE This article compares the UPDATE statement to the MERGE INTO statement, analyzing their respective performance differences and limitations. The Teradata MERGE INTO statement positively impacts performance by reducing I/O operations through the following properties. MERGE INTO offers an advantage in lower IOs as Teradata processes each data block only once …

Teradata Tactical Workload

04/11/202605/02/2023 by Roland Wenzlofsky

Introduction This blog post discusses tactical workloads on a Teradata system. Despite Teradata’s implementation of features that support tactical workloads, this workload category remains challenging to manage. Selecting an optimal physical design is essential to meet user expectations for query speed. Designing the Teradata tactical workload on a test environment can be frustrating, especially when …

The Importance of Up-to-Date Statistics for Teradata SQL Tuning

04/11/202605/02/2023 by Roland Wenzlofsky

1. Complete and up-to-date Statistics At the start of Teradata SQL Tuning, statistics are a vital concern. The Teradata Optimizer employs statistics to formulate the optimal execution plan for our query. The adequacy of statistics or dynamic AMP sampling varies according to the data demographics. To initiate optimization, updated statistics must be provided to the …

Teradata vs SQL Server: Key Architectural Differences and Performance Implications

04/11/202605/02/2023 by Roland Wenzlofsky

This article will highlight the contrasting architectural features of Teradata and SQL Server, along with their shared aspects and performance impacts. The piece titled “Teradata versus SQL Server” will be periodically updated.

Maximizing Performance with Teradata Dynamic AMP Sampling: An Introduction

04/11/202605/02/2023 by Roland Wenzlofsky

Introduction to Teradata Dynamic AMP Sampling Teradata calculates dynamic AMP samples for indexed columns (PI, USI, NUSI) at runtime without requiring statistics. These samples provide key information, including table cardinality and distinct values. They are stored in the FSG cache of each AMP’s table header. This process is referred to as dynamic AMP sampling. A …

Optimizing Queries with LIKE Operator in Teradata

04/11/202605/02/2023 by Roland Wenzlofsky

Learn how to optimize LIKE operator queries in Teradata to avoid full table scans and improve performance. Read on for expert tips and tricks.

Optimizing Teradata Queries: From No Index to Hashed NUSI

04/11/202604/28/2023 by Roland Wenzlofsky

The initial situation without any index In this blog, I will demonstrate how to optimize a query using Teradata’s tools. We will begin with the following test scenario: The data is evenly distributed. To demonstrate the query’s selectivity for the tested indexes we will define later, I assigned a significant portion of rows the same …

Teradata Rollbacks: Understanding the Impact on Performance and How to Avoid Them

04/11/202604/28/2023 by Roland Wenzlofsky

How to Abort the Teradata Rollback Executing a DML statement on a sizable table may trigger a prolonged ROLLBACK. In such cases, you must choose between waiting for the ROLLBACK to complete or terminating it. Cancelling a rollback avoids wasting additional resources, particularly when the system cannot run in parallel due to high skew, which …

The Importance of Minimizing Teradata I/O: Understanding Logical vs. Physical IOs and Their Impact on Performance

04/11/202604/28/2023 by Roland Wenzlofsky

Why is Teradata I/O so crucial? Minimizing Teradata I/O is a crucial aspect of performance tuning. IOs involve transferring data from storage to main memory, which is essential for Teradata to process data. Transferring data to the main memory is significantly slower than accessing data in the main memory or CPU cache. Minimizing IOs can …