Haki Benita • 9/16/2018

Be Careful With CTE in PostgreSQL

This technical article details a specific performance issue with Common Table Expressions (CTEs) in PostgreSQL versions 11 and prior. It demonstrates how a CTE can force materialization, preventing the query optimizer from pushing down filters like WHERE clauses and causing full table scans instead of efficient index usage. The post includes example queries, execution plans, and timing comparisons to illustrate the significant performance impact.

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#sql #postgresql #Query Optimization