This feature allows the vacuum to leverage multiple CPUs in order to process indexes. This enables us to perform index vacuuming and index cleanup with background workers. This adds a PARALLEL option to VACUUM command where the user can specify the number of workers that can be used to perform the command which is limited by the number of indexes on a table. Specifying zero as a number of workers will disable parallelism. This option can't be used with the FULL option.
Each index is processed by at most one vacuum process. Therefore parallel
vacuum can be used when the table has at least two indexes.
The parallel degree is either specified by the user or determined based on the number of indexes that the table has, and further limited by max_parallel_maintenance_workers. The index can participate in parallel
vacuum iff it's size is greater than min_parallel_index_scan_size.
Author: Masahiko Sawada and Amit Kapila
40d964ec99 Allow vacuum command to process indexes in parallel.
doc/src/sgml/config.sgml | 18 +-
doc/src/sgml/ref/vacuum.sgml | 61 +-
src/backend/access/heap/vacuumlazy.c | 1256 ++++++++++++++++++++++++++++++---
src/backend/access/transam/parallel.c | 26 +-
src/backend/commands/vacuum.c | 135 +++-
src/backend/postmaster/autovacuum.c | 2 +
src/bin/psql/tab-complete.c | 2 +-
src/include/access/heapam.h | 3 +
src/include/access/parallel.h | 4 +-
src/include/commands/vacuum.h | 12 +
src/test/regress/expected/vacuum.out | 34 +
src/test/regress/sql/vacuum.sql | 31 +
src/tools/pgindent/typedefs.list | 4 +
13 files changed, 1452 insertions(+), 136 deletions(-)