Statistics
A collection of 51 issues
How to Optimize Teradata Statistics and Avoid Heuristics: A Case Study
The Optimizer typically excels in utilizing statistics, yet examining the execution plan and cardinality estimations can sometimes be beneficial.
Since Teradata 14.10, I have habitually included the SHOW STATISTICS statement in my considerations. The resulting metrics can aid in identifying statistical issues.
Teradata Statistics - Avoid the Heuristics
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How to Improve Cardinality Estimations in Teradata: The Optimizer's Toolkit
Learn about Teradata Heuristics and Optimizer's approach to estimating cardinality for non-indexed columns in this article. Discover how skew improves estimations and why heuristics should be avoided.
Teradata Statistics: Understanding and Using Collected Metrics for Optimal Query Performance
Discover the importance of Teradata statistics in optimizing query execution plans. Learn how to collect statistics and when to use them for best results.
How to Analyze Teradata Tables for Multivalue Compression: A Less Costly Method Using SHOW STATISTICS VALUES COLUMN ON
Learn how to analyze Teradata tables for Multivalue compression without costly operations by using the SHOW STATISTICS VALUES COLUMN statement. This method delivers excellent compression suggestions with less resource and time consumption than traditional approaches. However, it only works for colum
Teradata Statistics Extrapolation: What it is and How it Works
Learn about Teradata Statistics Extrapolation, a technique that allows for reasonable estimations when querying historical data with stale statistics.
A Comprehensive Guide to Teradata Statistics: Common Misconceptions, Best Practices, and Real Reasons Behind Performance Degradation
Learn the truth about Teradata statistics and their impact on system performance. Address common misconceptions, follow best practices, and optimize your system for peak performance.
How To Speed Up Your PPI Tables With A Secondary Index
Improving Row Estimates with Teradata Check Constraints
Without Teradata CHECK Constraint
When a non-indexed column is utilized in a retrieval operation (i.e. WHERE statement) and lacks Teradata Check Constraints, the Optimizer employs heuristics to approximate the number of rows in the resulting set by inferring missing statistics.
The estimated number of rows is 7,342, equivalent
Teradata Heuristics for Nonindexed Columns
Learn about heuristics in Teradata optimizer and how they estimate the number of selected data rows for nonindexed columns in WHERE condition predicates. This post analyzes several queries and their estimates based on heuristics and provides insights on how to replace heuristic estimations with more