WindowAgg

memory

{"description":"This node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.","evidence":[{"archive_sha256":"555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f","label":"src/backend/executor/nodeWindowAgg.c","path":"src/backend/executor/nodeWindowAgg.c","sha256":"c365e6750bc77a89562254903d099c3e5914e001d3aae418322ccffc1d535d17","url":"https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2"},{"archive_sha256":"555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f","label":"src/backend/utils/sort/tuplestore.c","path":"src/backend/utils/sort/tuplestore.c","sha256":"27a85416bafed557006c705ab5d0c5dce3d3c1702812bb54d136f2ac4c41055a","url":"https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2"}],"mechanism":"tuplestore","source_notes":["If the tuplestore has spilled to disk, alternate reading and writing becomes quite expensive due to frequent buffer flushes. It's cheaper to force the entire partition to get spooled in one go.","Read the current row from the tuplestore, and save in ScanTupleSlot. (We can't rely on the outerplan's output slot because we may have to read beyond the current row. Also, we have to actually copy the row out of the tuplestore, since window function evaluation might cause the tuplestore to dump its state to disk.)","Window functions do not have to call this, but are encouraged to move the mark forward when possible to keep the tuplestore size down and prevent having to spill rows to disk."]}

source inventory

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