This tells you about allocations that have been made from the main shared memory segment. The original patch also tried to show information about dynamic shared memory allocation as well, but I decided to leave that problem for another time.
Andres Freund and Robert Haas, reviewed by Michael Paquier, Marti Raudsepp, Tom Lane, Álvaro Herrera, and Kyotaro Horiguchi.
ed10f32e37 Add pg_shmem_allocations view.
doc/src/sgml/catalogs.sgml | 85 ++++++++++++++++++++++++++++
doc/src/sgml/xfunc.sgml | 2 +-
src/backend/catalog/system_views.sql | 6 ++
src/backend/storage/ipc/shmem.c | 106 ++++++++++++++++++++++++++++++++++-
src/include/catalog/pg_proc.dat | 9 +++
src/include/storage/shmem.h | 3 +-
src/test/regress/expected/rules.out | 5 ++
7 files changed, 212 insertions(+), 4 deletions(-)