PostgreSQL plan nodes

Every line of an EXPLAIN plan is an executor node — one step PostgreSQL takes to run your query. This is a plain-language reference for all 44 of them: what each node does, when the planner chooses it, and whether seeing it should worry you.

Pasting a plan into the plan analyzer ? Click the next to any node to read its explanation inline.

Table access

Sample ScanSample Scan

Reads a random sample of a table for TABLESAMPLE queries.

Sequential ScanSeq Scan

Reads every row of a table from start to finish.

Tid Range ScanTid Range Scan

Scans a contiguous range of physical row locations.

Tid ScanTid Scan

Fetches rows directly by their physical location (ctid).

Index access

Bitmap Heap ScanBitmap Heap Scan

Reads heap pages in physical order from a bitmap of matching rows.

Bitmap Index ScanBitmap Index Scan

Scans an index to build a bitmap of matching row locations.

BitmapAndBitmapAnd

Intersects bitmaps from multiple indexes (AND).

BitmapOrBitmapOr

Unions bitmaps from multiple indexes (OR).

Index Only ScanIndex Only Scan

Answers the query from the index alone — no table fetch — when pages are all-visible.

Index ScanIndex Scan

Walks an index to find matching rows, then fetches each from the table.

Joins

HashHash

Builds the in-memory hash table used by a Hash Join.

Hash JoinHash Join

Builds a hash table from one side, probes it with the other.

Merge JoinMerge Join

Merges two inputs that are sorted on the join key.

Nested Loop JoinNested Loop

For each outer row, looks up matches on the inner side.

Aggregation & grouping

AggregateAggregate

Computes aggregates like count, sum, avg — plain, sorted, or hashed.

GroupGroup

Collapses adjacent equal rows in sorted input (GROUP BY without aggregates).

SetOpSetOp

Implements INTERSECT and EXCEPT (with ALL variants).

UniqueUnique

Removes adjacent duplicate rows from sorted input.

WindowAggWindowAgg

Computes window functions (OVER ...) across ordered partitions.

Ordering, materializing & caching

Incremental SortIncremental Sort

Sorts only by the remaining keys when input is already partially ordered.

MaterializeMaterialize

Buffers a child's rows once so they can be re-read cheaply.

MemoizeMemoize

Caches inner-side results keyed by parameters, for repeated lookups.

SortSort

Orders rows — in memory if it fits work_mem, otherwise on disk.

Combining & control flow

AppendAppend

Concatenates the outputs of several child plans (UNION ALL, partitions).

LimitLimit

Stops after N rows (and skips OFFSET rows).

LockRowsLockRows

Takes row-level locks for SELECT ... FOR UPDATE / FOR SHARE.

Merge AppendMerge Append

Merges already-sorted child outputs while preserving global order.

ProjectSetProjectSet

Evaluates set-returning functions in the SELECT list.

Recursive UnionRecursive Union

Drives WITH RECURSIVE CTEs by iterating until no new rows appear.

ResultResult

Emits computed rows, or gates execution on a one-time condition.

Parallelism

GatherGather

Collects rows from parallel worker processes into the leader.

Gather MergeGather Merge

Collects rows from workers while preserving sorted order.

Parallel-aware nodes (the “Parallel …” prefix)Parallel Seq Scan, Parallel Index Scan, Parallel Hash, …

Worker-cooperating variants of scans, hashes, and appends.

Derived & virtual scans

CTE ScanCTE Scan

Reads the materialized result of a WITH (CTE) query.

Custom ScanCustom Scan

A scan provided by an extension (e.g. a GPU/columnar engine).

Foreign ScanForeign Scan

Reads rows from a foreign table via a foreign data wrapper.

Function ScanFunction Scan

Reads rows returned by a set-returning function in FROM.

Named Tuplestore ScanNamed Tuplestore Scan

Reads trigger transition tables (OLD/NEW row sets).

Subquery ScanSubquery Scan

Reads the output of a subquery that couldn't be flattened.

Table Function ScanTable Function Scan

Reads rows from XMLTABLE / JSON_TABLE.

Values ScanValues Scan

Reads rows from an inline VALUES list.

WorkTable ScanWorkTable Scan

Reads the working set of the current recursion step.

Data modification

Insert / Update / Delete / Merge (ModifyTable)Insert

Applies INSERT / UPDATE / DELETE / MERGE to a table.

Subplans

SubPlan & InitPlanSubPlan

Sub-SELECTs evaluated per row (SubPlan) or once (InitPlan).