Re: Determining right size for max_fsm_pages on large

Vivek Khera writes:

> how many actual pages of data (and index) do you have? you want to
> see how many relpages you're relations are using in the pg_class
> view.

In 1 database:
select relname,relpages,reltuples from pg_class order by reltuples desc
limit 7;
relname | relpages | reltuples
----------------------------------+----------+-------------
pg_toast_988195_index | 148159 | 3.87392e+07
pg_toast_988195 | 9551848 | 3.87391e+07
pg_toast_988154_index | 123991 | 3.24807e+07
pg_toast_988154 | 8113192 | 3.24807e+07
msgrcpnts_mssgid_recpttp_recptid | 11192 | 2.52415e+06
messagerecipients | 16078 | 2.52415e+06
messagerecipients_pkey | 6375 | 2.52415e+06

In another:
select relname,relpages,reltuples from pg_class order by reltuples desc
limit 7;
relname | relpages | reltuples
---------------------------+----------+------------
pg_toast_2352480 | 14902626 | 3.0651e+07
pg_toast_2352480_index | 222896 | 3.0651e+07
archiveque_host | 11848 | 831494
archiveque_messageid | 13223 | 831494
archiveque_pkey | 4732 | 831494
archiveque | 161097 | 831494
archiveque_archive_que_id | 5119 | 831494

> i would venture to say if you have deleted rows in every
> single page, you'd want at least one entry per page of your table(s).

So about 15 million according to the above?

> once you're done with your migration, you should consider running a
> cluster on the big tables

Plan to.
Data will divide nicely by dates. All searches will
have date parameters.

After the migration is done and it is stable I should bring the value down?