doc: New cumulative stats subsystem obsoletes comment in maintenance.sgml

Hackers,

The new cumulative stats subsystem no longer has a "lost under heavy load"
problem so that parenthetical should go (or at least be modified).

These stats can be reset so some discussion about how the system uses them
given that possibility seems like it would be good to add here. I'm not
sure what that should look like though.

David J.

diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml
index 04a04e0e5f..360807c8f9 100644
--- a/doc/src/sgml/maintenance.sgml
+++ b/doc/src/sgml/maintenance.sgml
@@ -652,9 +652,8 @@ vacuum insert threshold = vacuum base insert threshold
+ vacuum insert scale fac
tuples to be frozen by earlier vacuums. The number of obsolete tuples
and
the number of inserted tuples are obtained from the cumulative
statistics system;
it is a semi-accurate count updated by each <command>UPDATE</command>,
- <command>DELETE</command> and <command>INSERT</command> operation.
(It is
- only semi-accurate because some information might be lost under heavy
- load.) If the <structfield>relfrozenxid</structfield> value of the
table
+ <command>DELETE</command> and <command>INSERT</command> operation.
+ If the <structfield>relfrozenxid</structfield> value of the table
is more than <varname>vacuum_freeze_table_age</varname> transactions
old,
an aggressive vacuum is performed to freeze old tuples and advance
<structfield>relfrozenxid</structfield>; otherwise, only pages that
have been modified