pg_buffercache: document column meanings

Improve documentation for usagecount and relforknumber.
Backpatch to 9.3
Suggestion from Satoshi Nagayasu

diff --git a/doc/src/sgml/pgbuffercache.sgml b/doc/src/sgml/pgbuffercache.sgml
index 1d7d95f9d7de3d972374d05a96308971f5cf961e..685351f11eb52b2942f41b6ec59b2a950c0d1328 100644 (file)
--- a/doc/src/sgml/pgbuffercache.sgml
+++ b/doc/src/sgml/pgbuffercache.sgml
@@ -84,7 +84,8 @@
       relforknumber
       smallint
       
-      Fork number within the relation
+      Fork number within the relation;  see
+      include/storage/relfilenode.h
      
 
      
@@ -98,7 +99,7 @@
       usagecount
       smallint
       
-      Page LRU count
+      Clock-sweep access count