327 technical articles on Teradata, Snowflake, Databricks, SQL tuning and data warehouse architecture — written from production experience, not vendor decks.
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 accurate ones.
Learn about referential integrity and how it ensures data consistency in databases. Discover soft referential integrity and its use in inner join elimination.
Learn how to optimize joins in Teradata with this case study. Discover how simple changes in query text can improve query performance.
Natural skew may hinder join performance, but the PRPD capability in Teradata 14 can alleviate this problem. However, PRPD may not detect all potential applications if skewed values are not evident in the statistics. If your Teradata version is below 14, PRPD is unavailable. To address this, you can use a technique based on the …
Learn how express requests work in Teradata, bypassing stages like syntax checking and permission checking, and how Teradata 14.10 offers a new feature to expedite them.
Learn how to optimize Teradata performance with these general tuning ideas. From changing one parameter at a time to testing on the target system.
To optimize Teradata SQL performance, it is crucial to identify the root cause of any issues. The SQL statement itself is typically not the culprit but rather one or more stages of the execution plan. This article does not cover genuine optimization techniques. Instead, it presents a pragmatic method for query optimization. I have noticed …
A Teradata NUSI offers an alternative access path that may reduce resource use. Distribution hashing in another product, such as Redshift, is not evidence that it implements Teradata-style secondary indexes. Teradata has two types of secondary indexes: the Unique Secondary Index (USI) and the Non-Unique Secondary Index (NUSI). Although they may seem similar, these indexes …
Learn about the benefits of partitioned primary index (PPI) in Teradata, a method for reducing I/Os and improving performance in database systems.
Use Teradata REGEXP_SIMILAR to validate a three-digit substring before converting it to an integer; return a defined fallback for invalid input.
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