number of relations reported by vacuumdb -av

Hi,

I have a PostgreSQL installation with 8 databases (counting postgres,
template0, and template1). I run 'vacuumdb -z' daily on 3 of the largest
user databases. The vacuumdb logs show the 'max_fsm_pages' need to be
increased with almost each vacuum. So I did a 'vacuumdb -av' on all the
db's:
> INFO:  free space map contains 81016 pages in 100 relations
> DETAIL:  A total of 80000 page slots are in use (including overhead).
> 187792 page slots are required to track all free space.
> Current limits are:  80000 page slots, 1000 relations, using 534 KB.
> NOTICE:  number of page slots needed (187792) exceeds max_fsm_pages (80000)
> HINT:  Consider increasing the configuration parameter "max_fsm_pages" to a value over 187792.
> VACUUM

I have a couple questions.

1) I can increase 'max_fsm_pages' from 80K to 200K, but why does it keep
growing?

The main database sees on average 2500-5000 rows inserted per day, and
deletes are relatively small (although I don't have stats on deletes).

2) How is '100 relations' getting calculated?

If I connect to each one of my 8 db's and do:

select count(*) from pg_class;

The total number of relations is 1725. So shouldn't I increase
'max_fsm_relations' from 1000 to 1725?

Thank you in advance.

-- irene
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Irene Barg                    Email:  ibarg@noao.edu
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