Answer
Multi-column statistics capture value correlations across columns to help the optimizer choose better join orders and filter strategies.
Quick Answer
Multi-column statistics: by default, PostgreSQL assumes column independence (poor estimate for correlated columns). CREATE STATISTICS stat_name (dependencies) ON col1, col2 FROM table tells PostgreSQL to track correlation between columns. This improves row count estimates for queries filtering on multiple correlated columns (city + zip code, product + category). Introduced in PostgreSQL 10, extended in later versions.
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SugharaIQ Editorial Team
Verified Answer
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Source: SugharaIQ