Hash Join

memory

{"description":"Hash-join execution can partition work into batches backed by temporary files. This describes hash-join batching, not the spill policy of aggregate or Memoize nodes.","evidence":[{"archive_sha256":"555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f","label":"src/backend/executor/nodeHashjoin.c","path":"src/backend/executor/nodeHashjoin.c","sha256":"4a72b0db253c1905c415462cfe56a2327ac65507c607b6d699d2717fa624ad56","url":"https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2"},{"archive_sha256":"555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f","label":"src/backend/executor/nodeHashjoin.c","path":"src/backend/executor/nodeHashjoin.c","sha256":"4a72b0db253c1905c415462cfe56a2327ac65507c607b6d699d2717fa624ad56","url":"https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2"}],"mechanism":"hash-batches","source_notes":["If the inner side tuples of a hash join do not fit in memory, the hash join can be executed in multiple batches.","If the statistics on the inner side relation are accurate, planner chooses a multi-batch strategy and estimates the number of batches.","The query executor measures the real size of the hashtable and increases the number of batches if the hashtable grows too large.","The number of batches is always a power of two, so an increase in the number of batches doubles it."]}

source inventory

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