Query analysis

The Analysis tab in any query view runs EXPLAIN (or EXPLAIN ANALYZE) for the current SQL and renders the plan as a hierarchy.

EXPLAIN vs EXPLAIN ANALYZE

• EXPLAIN — the planner’s cost estimate. No execution, safe on production.
• EXPLAIN ANALYZE — actually runs the query and measures every node. We wrap it in (ANALYZE, VERBOSE, BUFFERS, SETTINGS, FORMAT JSON) so you also get buffer / IO counters and the relevant planner GUC values.

Reading the tree

Each node shows:

• Node type — Seq Scan / Index Scan / Hash Join / Sort / …
• Target — table, alias, or index name when applicable.
• Cost or actual time — when ANALYZE is on, you get the real number; otherwise the planner’s Total Cost.
• Rows — actual row count × loops when ANALYZE is on, planner estimate otherwise.
• Condition — Index Cond or Hash Cond if present.
• Filter + rows-removed-by-filter counter.

The left border of each node is color-coded by its proportional weight: green ≤25%, orange ≤66%, red ≥66%. Click anywhere on the row to expand or collapse its children.

What to look for

Patterns the heat bar tends to expose:

• A Seq Scan that’s hot but the table has an index on the filter column → add it to the WHERE plan.
• A Nested Loop whose inner Index Scan loops millions of times → rewrite as a Hash Join or push a JOIN condition.
• Big rows-removed-by-filter counts on the outer plan node → pre-filter earlier in the pipeline.