> > This patch improves the documentation for the shared_buffers GUC param.

>
> I'd suggest that the runtime.sgml description explicitly say "values of
> at least a few thousand are recommended for production installations".

Neil Conway

diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml
index 3f530f35784fecefc21c9eb2a404ebb94ef52489..34321cae52d16760057ffc2a70cf2828a3fe6c3e 100644 (file)
--- a/doc/src/sgml/runtime.sgml
+++ b/doc/src/sgml/runtime.sgml
@@ -1,5 +1,5 @@
 
 
 
@@ -380,11 +380,12 @@ FATAL 1:  ShmemCreate: cannot create region
 
 IpcSemaphoreCreate: semget(key=5440026, num=16, 01600) failed: No space left on device
 
-     does not mean you've run out of disk space. It
-     means your kernel's limit on the number of System V semaphores is
-     smaller than the number PostgreSQL wants
-     to create. As above, you may be able to work around the problem by
-     starting the postmaster with a reduced number of allowed connections
+     does not mean you've run out of disk
+     space. It means your kernel's limit on the number of 
+     class="osname">System V semaphores is smaller than the number
+     PostgreSQL wants to create. As above,
+     you may be able to work around the problem by starting the
+     postmaster with a reduced number of allowed connections
      (-N switch), but you'll eventually want to
      increase the kernel limit.
     
@@ -1838,8 +1839,21 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir'
       
        
         Sets the number of shared memory buffers used by the database
-        server. The default is 64. Each buffer is typically 8192 bytes.
-        This option can only be set at server start.
+        server. The default is 64. Each buffer is typically 8192
+        bytes. This must be greater than 16, as well as at least twice
+        the value of MAX_CONNECTIONS; however, a
+        higher value can often improve performance on modern
+        machines. Values of at least a few thousand are recommended
+        for production installations. This option can only be set at
+        server start.
+       
+
+       
+        Increasing this parameter may cause PostgreSQL
+        to request more System V shared
+        memory than your operating system's default configuration
+        allows. See  for information on how to
+        adjust these parameters, if necessary.
        
       
      
@@ -2165,8 +2179,9 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir'
       WAL_BUFFERS (integer)
       
        
-        Number of disk-page buffers in shared memory for WAL logging.
-   This option can only be set at server start.
+        Number of disk-page buffers in shared memory for WAL
+        logging. The default is 4. This option can only be set at
+        server start.
        
       
      


diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample

index 07ba73b5410d7b6d0e147a92a12c5b7cf78e5807..f43e488ba8685400b5f33d71e6e75f0bb3ad6be9 100644 (file)

--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -47,7 +47,7 @@
 #
 #  Shared Memory Size
 #
-#shared_buffers = 64       # 2*max_connections, min 16, typically 8KB each
+#shared_buffers = 64       # at least 2*max_connections, min 16, 8KB each
 #max_fsm_relations = 1000  # min 10, fsm is free space map, ~40 bytes
 #max_fsm_pages = 10000     # min 1000, fsm is free space map, ~6 bytes
 #max_locks_per_transaction = 64    # min 10

diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 07ba73b5410d7b6d0e147a92a12c5b7cf78e5807..f43e488ba8685400b5f33d71e6e75f0bb3ad6be9 100644 (file)
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -47,7 +47,7 @@
 #
 #  Shared Memory Size
 #
-#shared_buffers = 64       # 2*max_connections, min 16, typically 8KB each
+#shared_buffers = 64       # at least 2*max_connections, min 16, 8KB each
 #max_fsm_relations = 1000  # min 10, fsm is free space map, ~40 bytes
 #max_fsm_pages = 10000     # min 1000, fsm is free space map, ~6 bytes
 #max_locks_per_transaction = 64    # min 10