pgsql: Introduce IndexAM fields for parallel vacuum.

Introduce IndexAM fields for parallel vacuum.

Introduce new fields amusemaintenanceworkmem and amparallelvacuumoptions
in IndexAmRoutine for parallel vacuum. The amusemaintenanceworkmem tells
whether a particular IndexAM uses maintenance_work_mem or not. This will
help in controlling the memory used by individual workers as otherwise,
each worker can consume memory equal to maintenance_work_mem. The
amparallelvacuumoptions tell whether a particular IndexAM participates in
a parallel vacuum and if so in which phase (bulkdelete, vacuumcleanup) of
vacuum.

Author: Masahiko Sawada and Amit Kapila
Reviewed-by: Dilip Kumar, Amit Kapila, Tomas Vondra and Robert Haas
Discussion:
https://postgr.es/m/CAD21AoDTPMgzSkV4E3SFo1CH_x50bf5PqZFQf4jmqjk-C03BWg@mail.gmail.com
https://postgr.es/m/CAA4eK1LmcD5aPogzwim5Nn58Ki+74a6Edghx4Wd8hAskvHaq5A@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/4d8a8d0c738410ec02aab46b1ebe1835365ad384

Modified Files
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contrib/bloom/blutils.c | 4 +++
doc/src/sgml/indexam.sgml | 4 +++
src/backend/access/brin/brin.c | 4 +++
src/backend/access/gin/ginutil.c | 4 +++
src/backend/access/gist/gist.c | 4 +++
src/backend/access/hash/hash.c | 3 ++
src/backend/access/nbtree/nbtree.c | 3 ++
src/backend/access/spgist/spgutils.c | 4 +++
src/include/access/amapi.h | 4 +++
src/include/commands/vacuum.h | 38 ++++++++++++++++++++++++
src/test/modules/dummy_index_am/dummy_index_am.c | 3 ++
11 files changed, 75 insertions(+)