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

1 files changed, 3 insertions, 3 deletions

diff --git a/src/backend/utils/init/globals.c b/src/backend/utils/init/globals.c
index 5eaee88d969..aea95c8a69b 100644
--- a/src/backend/utils/init/globals.c
+++ b/src/backend/utils/init/globals.c
@@ -22,7 +22,7 @@
 #include "libpq/libpq-be.h"
 #include "libpq/pqcomm.h"
 #include "miscadmin.h"
-#include "storage/backendid.h"
+#include "storage/procnumber.h"
 
 
 ProtocolVersion FrontendProtocol;
@@ -83,9 +83,9 @@ char		postgres_exec_path[MAXPGPATH];	/* full path to backend */
 /* note: currently this is not valid in backend processes */
 #endif
 
-BackendId	MyBackendId = InvalidBackendId;
+ProcNumber	MyProcNumber = INVALID_PROC_NUMBER;
 
-BackendId	ParallelLeaderBackendId = InvalidBackendId;
+ProcNumber	ParallelLeaderProcNumber = INVALID_PROC_NUMBER;
 
 Oid			MyDatabaseId = InvalidOid;