Alena Rybakina

Developer at Postgres Professional

About

I am a PostgreSQL database developer in the field of optimization, namely, I write code for the optimizer and statistics. I'm active contributor in PostgreSQL Community: several patches were committed (OR-to-ANY transformation and Values-to-ANY transformation). I have participated and gave talks in conferences: PGConf Canada 2024, 2025, PG Conf Ivory SQL 2025.

Alena Rybakina has presented the following presentations

    Alena Rybakina When the Optimizer Guesses Wrong: A Reproducibility Lens on Cardinality Estimation at PG Down Under 2026

    presented by Alena Rybakina

    For decades, the query optimizer's hardest problem has not been searching for a plan - it has been predicting how many rows each operator will produce. Cardinality estimation errors, and underestimation especially, compound multiplicatively across joins: estimate one row against a reality of a million, and the optimizer commits to a nested-loop plan that runs orders of magnitude too slow. This ...

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    Development
    Alena Rybakina Pull-up Optimization in the Postgres Planner at PG Down Under 2025

    presented by Alena Rybakina

    Pull-up is an optimization that already exists in PostgreSQL’s planner. It rewrites eligible subqueries into the main query level so that the planner can work with a unified join tree rather than treating subqueries as independent nodes.

    Currently, PostgreSQL applies pull-up to several common subquery forms, including: - IN subqueries - EXISTS subqueries - ANY expressions (where applicabl...

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    Fri 17 2025 Development