Fix documentation for System V semaphores.

The formulas for SEMMNI and SEMMNS do not include the archiver
process, which was converted to an auxiliary process in v14, and
the WAL summarizer process, which was introduced in v17.  This
commit corrects these formulas and adds a missing reference to
max_wal_senders nearby.  Since this section of the documentation
tends to be incorrect quite often, we should likely give up on
documenting the exact formulas in favor of something less fragile,
but that is left as a future exercise.

Reported-by: Sami Imseih
Reviewed-by: Sami Imseih
Discussion: https://postgr.es/m/20240517164452.GA1914161%40nathanxps13
Backpatch-through: 12

diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml
index 6047b8171d4e8016fc20df8a9f6bd7a8dc8af0f0..883a849e6f52d7c9d257c9f6ac0df1a7d6ea063c 100644 (file)
--- a/doc/src/sgml/runtime.sgml
+++ b/doc/src/sgml/runtime.sgml
@@ -781,13 +781,13 @@ psql: error: connection to server on socket "/tmp/.s.PGSQL.5432" failed: No such
        
         SEMMNI
         Maximum number of semaphore identifiers (i.e., sets)
-        at least ceil((max_connections + autovacuum_max_workers + max_wal_senders + max_worker_processes + 5) / 16) plus room for other applications
+        at least ceil((max_connections + autovacuum_max_workers + max_wal_senders + max_worker_processes + 7) / 16) plus room for other applications
        
 
        
         SEMMNS
         Maximum number of semaphores system-wide
-        ceil((max_connections + autovacuum_max_workers + max_wal_senders + max_worker_processes + 5) / 16) * 17 plus room for other applications
+        ceil((max_connections + autovacuum_max_workers + max_wal_senders + max_worker_processes + 7) / 16) * 17 plus room for other applications
        
 
        
@@ -838,7 +838,8 @@ psql: error: connection to server on socket "/tmp/.s.PGSQL.5432" failed: No such
     When using System V semaphores,
     PostgreSQL uses one semaphore per allowed connection
     (), allowed autovacuum worker process
-    () and allowed background
+    (), allowed WAL sender process
+    (), and allowed background
     process (), in sets of 16.
     Each such set will
     also contain a 17th semaphore which contains a magic
@@ -852,7 +853,7 @@ psql: error: connection to server on socket "/tmp/.s.PGSQL.5432" failed: No such
     linkend="sysvipc-parameters"/>).  The parameter SEMMNI
     determines the limit on the number of semaphore sets that can
     exist on the system at one time.  Hence this parameter must be at
-    least ceil((max_connections + autovacuum_max_workers + max_wal_senders + max_worker_processes + 5) / 16).
+    least ceil((max_connections + autovacuum_max_workers + max_wal_senders + max_worker_processes + 7) / 16).
     Lowering the number
     of allowed connections is a temporary workaround for failures,
     which are usually confusingly worded No space