pgsql: Replace BackendIds with 0-based ProcNumbers

Replace BackendIds with 0-based ProcNumbers

Now that BackendId was just another index into the proc array, it was
redundant with the 0-based proc numbers used in other places. Replace
all usage of backend IDs with proc numbers.

The only place where the term "backend id" remains is in a few pgstat
functions that expose backend IDs at the SQL level. Those IDs are now
in fact 0-based ProcNumbers too, but the documentation still calls
them "backend ids". That term still seems appropriate to describe what
the numbers are, so I let it be.

One user-visible effect is that pg_temp_0 is now a valid temp schema
name, for backend with ProcNumber 0.

Reviewed-by: Andres Freund
Discussion: https://www.postgresql.org/message-id/8171f1aa-496f-46a6-afc3-c46fe7a9b407@iki.fi

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/024c521117579a6d356050ad3d78fdc95e44eefa

Modified Files
--------------
doc/src/sgml/config.sgml | 2 +-
doc/src/sgml/monitoring.sgml | 18 ++---
doc/src/sgml/storage.sgml | 2 +-
doc/src/sgml/xact.sgml | 4 +-
src/backend/access/transam/README | 10 +--
src/backend/access/transam/clog.c | 18 ++---
src/backend/access/transam/multixact.c | 64 ++++++++--------
src/backend/access/transam/parallel.c | 10 +--
src/backend/access/transam/twophase.c | 43 ++++++-----
src/backend/access/transam/xact.c | 9 ++-
src/backend/access/transam/xlogprefetcher.c | 2 +-
src/backend/access/transam/xlogutils.c | 6 +-
src/backend/backup/basebackup_incremental.c | 2 +-
src/backend/catalog/catalog.c | 14 ++--
src/backend/catalog/namespace.c | 30 ++++----
src/backend/catalog/storage.c | 30 ++++----
src/backend/commands/async.c | 89 ++++++++++------------
src/backend/commands/dbcommands.c | 2 +-
src/backend/commands/indexcmds.c | 2 +-
src/backend/commands/sequence.c | 2 +-
src/backend/libpq/pqmq.c | 10 +--
src/backend/postmaster/pgarch.c | 12 +--
src/backend/postmaster/walsummarizer.c | 16 ++--
.../replication/logical/applyparallelworker.c | 4 +-
src/backend/replication/slot.c | 2 +-
src/backend/replication/walsender.c | 2 +-
src/backend/storage/buffer/buf_init.c | 2 +-
src/backend/storage/buffer/bufmgr.c | 30 ++++----
src/backend/storage/buffer/localbuf.c | 6 +-
src/backend/storage/ipc/procarray.c | 44 +++++------
src/backend/storage/ipc/procsignal.c | 36 ++++-----
src/backend/storage/ipc/sinvaladt.c | 45 +++++------
src/backend/storage/ipc/standby.c | 6 +-
src/backend/storage/lmgr/lmgr.c | 2 +-
src/backend/storage/lmgr/lock.c | 26 +++----
src/backend/storage/lmgr/predicate.c | 10 +--
src/backend/storage/lmgr/proc.c | 39 +++++-----
src/backend/storage/smgr/md.c | 4 +-
src/backend/storage/smgr/smgr.c | 2 +-
src/backend/utils/activity/backend_status.c | 50 ++++++------
src/backend/utils/adt/dbsize.c | 14 ++--
src/backend/utils/adt/lockfuncs.c | 13 ++--
src/backend/utils/adt/mcxtfuncs.c | 7 +-
src/backend/utils/adt/pgstatfuncs.c | 50 ++++++------
src/backend/utils/cache/inval.c | 4 +-
src/backend/utils/cache/relcache.c | 30 ++++----
src/backend/utils/error/csvlog.c | 4 +-
src/backend/utils/error/elog.c | 6 +-
src/backend/utils/error/jsonlog.c | 4 +-
src/backend/utils/init/globals.c | 6 +-
src/backend/utils/time/snapmgr.c | 6 +-
src/common/relpath.c | 24 +++---
src/include/access/twophase.h | 2 +-
src/include/catalog/namespace.h | 3 +-
src/include/common/relpath.h | 4 +-
src/include/libpq/pqmq.h | 2 +-
src/include/miscadmin.h | 5 --
src/include/postmaster/postmaster.h | 2 +-
src/include/storage/backendid.h | 41 ----------
src/include/storage/lock.h | 18 ++---
src/include/storage/proc.h | 36 ++++-----
src/include/storage/procarray.h | 8 +-
src/include/storage/proclist.h | 38 ++++-----
src/include/storage/proclist_types.h | 18 +++--
src/include/storage/procnumber.h | 43 +++++++++++
src/include/storage/procsignal.h | 4 +-
src/include/storage/relfilelocator.h | 29 +++----
src/include/storage/sinval.h | 4 +-
src/include/storage/smgr.h | 2 +-
src/include/utils/backend_status.h | 14 ++--
src/include/utils/rel.h | 2 +-
71 files changed, 571 insertions(+), 579 deletions(-)