Query Plan Visualizer

How it works

Paste PostgreSQL EXPLAIN / EXPLAIN ANALYZE output (text or FORMAT JSON) or MySQL EXPLAIN FORMAT=JSON. The plan is drawn as a node tree with cost, estimated vs actual rows, inclusive and exclusive time per node, and checked for the classic problems: row misestimates, sequential scans that discard most rows, sorts and hashes spilling to disk, nested loops over large inputs — each with a concrete fix such as a specific CREATE INDEX statement or work_mem setting.

• PostgreSQL text plans are parsed by the "->" indentation; node headers give cost=startup..total rows width and (actual time=startup..total rows loops); detail lines (Filter, Rows Removed by Filter, Sort Method, Buckets/Batches, Buffers…) are mapped to the same keys as FORMAT JSON.
• Actual time and rows are per-loop averages (PostgreSQL docs), so inclusive time = actual total time × loops; exclusive time = inclusive − children's inclusive time. Under Gather, time is divided by the number of participating processes.
• Misestimate = max(estimated, actual)/min(…) rows per loop at or above the threshold (and ≥100 rows absolute difference).
• Rules: Seq Scan with Filter removing ≥90% of ≥1000 rows; Index Scan still filtering; Sort Method external/Disk; Hash Batches > 1; Nested Loop with ≥1000 outer rows and a sequential inner side or ≥10k inner loops; lossy bitmaps; workers not launched; heap fetches in index-only scans.
• Index candidates take equality-compared filter columns first, then the first range column (B-tree column-order rule); functions in filters call for expression indexes and leading-wildcard LIKE for pg_trgm.
• MySQL: access_type ALL / index, filtered %, attached_condition columns, using_join_buffer, using_filesort and using_temporary_table (EXPLAIN FORMAT=JSON has estimates only, no timings).