trino-explain-plan-review

What problem does it solve?

This Skill helps you pinpoint why a Trino query is slow by interpreting EXPLAIN and EXPLAIN ANALYZE output, including distributed fragments, exchanges, skew, and operator-level bottlenecks.

Core Features & Use Cases

• Plan-type driven diagnosis: Read DISTRIBUTED, LOGICAL, IO, and VALIDATE views to confirm what the engine decided to do.
• Exchange and fragment analysis: Identify RemoteExchange patterns and fragment types (SINGLE/HASH/ROUND_ROBIN/BROADCAST/SOURCE) to reduce shuffle and network cost.
• Runtime metric interpretation: Detect skew using input row variance, spot spill and blocked-time issues, and compare estimated vs actual rows to catch stale stats and misplanning.
• Common slow-plan anti-patterns: Find missing partition pruning, predicate pushdown failures, cross joins, accidental extra repartitioning, and small-file split explosions.

Quick Start

Ask the agent to run EXPLAIN ANALYZE for your query and review the distributed fragments, RemoteExchange count, skew signals (input avg vs std.dev), and estimated-versus-actual row disparities to recommend the most likely fix.