--- title: All Your GUCs in a Row: The geqo Family | daily.dev description: PostgreSQL's Genetic Query Optimizer (GEQO) has seven configuration parameters (GUCs), but only one truly matters for day-to-day operations: geqo_threshold.... canonical: https://daily.dev/posts/all-your-gucs-in-a-row-the-geqo-family-jnt577kaa twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: All Your GUCs in a Row: The geqo Family | daily.dev og:description: PostgreSQL's Genetic Query Optimizer (GEQO) has seven configuration parameters (GUCs), but only one truly matters for day-to-day operations: geqo_threshold.... og:url: https://daily.dev/posts/all-your-gucs-in-a-row-the-geqo-family-jnt577kaa og:image: https://api.daily.dev/og/posts/jnt577kaA.png og:image:alt: All Your GUCs in a Row: The geqo Family og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # All Your GUCs in a Row: The geqo Family **[Planet PostgreSQL](https://daily.dev/sources/planet-postgresql)** · 13 min read · 0 upvotes · 0 comments ## Summary PostgreSQL's Genetic Query Optimizer (GEQO) has seven configuration parameters (GUCs), but only one truly matters for day-to-day operations: geqo_threshold. GEQO kicks in when a query involves too many relations for the regular dynamic programming planner to handle exhaustively. The threshold defaults to 12 — calibrated for 1990s hardware — and raising it into the mid-to-high teens is usually safe on modern machines. The other six parameters (geqo, geqo_effort, geqo_pool_size, geqo_generations, geqo_selection_bias, geqo_seed) are either a master switch to leave on, or hyperparameters that are practically untunable without a proper benchmark workload. GEQO is widely considered de facto deprecated within the PostgreSQL project, with a 2021 pgsql-hackers thread explicitly calling it that, though no replacement has landed yet. Key practical advice: leave geqo on as a safety backstop, raise geqo_threshold carefully while monitoring planning time, keep it above collapse limits, and treat queries hitting GEQO as a signal to investigate the query structure rather than tune the algorithm. ## Full article daily.dev links to this article rather than hosting it. 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