Extended Statistics | Agent Skills Atlas

About this skill

PostgreSQL's extended statistics — CREATE STATISTICS, pgstatisticext, pgstatisticextdata — the 4 stat kinds (dependencies / ndistinct / mcv / expressions) that help the planner handle correlated columns, multi-column NDVs, and expression cardinality. Covers src/backend/statistics/extendedstats.c + dependencies.c + mcv.c + mvdistinct.c. Loads when the user asks about extended stats syntax, when to CREATE STATISTICS, why a query has bad estimates on correlated columns, ndistinct for GROUP BY estimation, MCV lists in the extended-stats context, or the planner's clauselistselectivityext selectivity path. Skip when the ask is about pgstatistic (single-column stats — the sibling; see analyze-block-and-reservoir-sampling idiom) or about ANALYZE mechanics (that's analyze.c — different code path).

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0 potential findings · Scanned 11/4/2026 · Scanner 0.2.1

Content SHA-256: f1c39098d9b2b7fadf1e88e5f2726b3e074d8f03f31084473d688ac7133aee1e

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Original listing metadata

Original name

extended-statistics

Original description

PostgreSQL's extended statistics — `CREATE STATISTICS`, `pg_statistic_ext`, `pg_statistic_ext_data` — the 4 stat kinds (dependencies / ndistinct / mcv / expressions) that help the planner handle correlated columns, multi-column NDVs, and expression cardinality. Covers `src/backend/statistics/extended_stats.c` + `dependencies.c` + `mcv.c` + `mvdistinct.c`. Loads when the user asks about extended stats syntax, when to `CREATE STATISTICS`, why a query has bad estimates on correlated columns, ndistinct for GROUP BY estimation, MCV lists in the extended-stats context, or the planner's `clauselist_selectivity_ext` selectivity path. Skip when the ask is about `pg_statistic` (single-column stats — the sibling; see `analyze-block-and-reservoir-sampling` idiom) or about ANALYZE mechanics (that's `analyze.c` — different code path).

About this listing

Category: Science & research
Reported license: PostgreSQL
Listing language (estimated): English
Review status: Not individually reviewed
Agent compatibility: Atlas installation supports Claude Code, Codex, and Cursor. Skill-specific dependencies and features are checked during setup.