Why do stale or low-quality statistics cause bad plans?

Problem Statement

Explanation

Cardinality estimates drive plan choices. If the engine expects far fewer or far more rows than reality, it can pick scans, sorts, or joins that are too expensive. Refresh statistics and increase histogram detail for skew. For filtered workloads, use filtered statistics or extended stats when available.

Code Solution

SolutionRead Only

-- Postgres
ANALYZE orders;
-- SQL Server
UPDATE STATISTICS orders WITH FULLSCAN;

Practice Sets

This question appears in the following practice sets:

Query Plans & Performance Tuning

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Why do stale or low-quality statistics cause bad plans?

Problem Statement

Explanation

Code Solution

Practice Sets

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Why do stale or low-quality statistics cause bad plans?

Problem Statement

Explanation

Code Solution

Practice Sets

Related Questions

Which SQL statement retrieves all columns and rows from a table named employees?

Which clause filters rows before aggregation and affects which rows are grouped?

What is the default sort order when ORDER BY is used without ASC or DESC?

Which construct is commonly used to paginate results in SQL engines like Postgres and MySQL?

Which predicate correctly checks for missing values in standard SQL?

More from SQL & Databases

Master Interviews
Anywhere, Anytime