Index Only Scan

Uses index values for the result and checks tuple visibility, visiting the heap when the visibility map does not suffice.

Reading PG 18·Select a recorded version

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Core node tag: T_IndexOnlyScan
Structured EXPLAIN Node Type: Index Only Scan
Inputs: An index, relation and visibility information
Output: Qualified tuples from index values
Executor initializer: ExecInitIndexOnlyScan
Memory mechanism: unclassified
evidence kind: source and documentation
explain names: Index Only Scan
explain prefixes: Parallel, Async
node tag: T_IndexOnlyScan
parallel callbacks: ExecIndexOnlyScanEstimate, ExecIndexOnlyScanInitializeDSM, ExecIndexOnlyScanInitializeWorker, ExecIndexOnlyScanReInitializeDSM, ExecIndexOnlyScanRetrieveInstrumentation
partial modes: Unknown
runtime verified: false
strategies: Unknown

Definition PG 18

Uses index values for the result and checks tuple visibility, visiting the heap when the visibility map does not suffice.

EXPLAIN labels in this source build

Text-format label	Structured node identity
Index Only Scan	Index Only Scan

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Complete source facts

memory

{"description":"This extraction does not assign a universal memory limit or spill policy to this node. Inspect the same-build implementation and its expressions or provider.","evidence":[{"archive_sha256":"555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f","label":"src/backend/executor/nodeIndexonlyscan.c","path":"src/backend/executor/nodeIndexonlyscan.c","sha256":"357d4ddbd6ba5d9b02f04185e579e2f2dc889d0d94875580770c8649cc427e6d","url":"https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2"}],"mechanism":"unclassified","source_notes":[]}

source inventory

{"executor":"src/backend/executor/execProcnode.c","explain":"src/backend/commands/explain.c","implementation":"src/backend/executor/nodeIndexonlyscan.c"}

Source references

Full definition and evidence JSON

Definition sources

center · PostgreSQL 18 · 555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f

Text language: en · 555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f