Updated FSM display for VACUUM VERBOSE
I have trouble understanding the current output of VACUUM VERBOSE when
it displays FSM information.
The current output is:
INFO: free space map: 49 relations, 17266 pages stored; 18768 total
pages used
DETAIL: FSM size: 1000 relations + 18000 pages = 171 kB shared memory.
NOTICE: the number of page slots needed (18768) exceeds max_fsm_pages
(18000)
HINT: Consider increasing the configuration parameter "max_fsm_relations"
to a value over 18768.
The problem I have is that the relations part is mixed with the pages
part, and the numbers aren't easily comparable. I have attached a patch
which makes the information easier to understand. Here is one where the
FSM is large enough:
INFO: free space map: 48 relations with free space, maximum of 1000 relations trackable
INFO: 35 pages stored, 768 pages used (with overhead)
INFO: 768 pages required to store all freespace, maximum of 18000 pages allocatable (171 kB)
and one that is too small:
INFO: free space map: 49 relations with free space, maximum of 1000 relations trackable
INFO: 17266 pages stored, 18000 pages used (with overhead)
INFO: 18768 pages required to store all freespace, maximum of 18000 pages allocatable (171 kB)
NOTICE: the number of page slots needed (18768) exceeds max_fsm_pages (18000)
HINT: Consider increasing the configuration parameter "max_fsm_relations"
to a value over 18768.
I find this output cleaner and easier to understand. The "pages used"
value will match either the "required" or "maximum" value on the line
below.
--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073Attachments:
/pgpatches/fsmtext/plainDownload+25-16
pgman wrote:
INFO: free space map: 49 relations with free space, maximum of 1000 relations trackable
INFO: 17266 pages stored, 18000 pages used (with overhead)
INFO: 18768 pages required to store all freespace, maximum of 18000 pages allocatable (171 kB)
NOTICE: the number of page slots needed (18768) exceeds max_fsm_pages (18000)
HINT: Consider increasing the configuration parameter "max_fsm_relations"
to a value over 18768.I find this output cleaner and easier to understand. The "pages used"
value will match either the "required" or "maximum" value on the line
below.
The "pages used" sentence above is wrong, and it seems the computation
is wrong too. I just connected to another database, created, inserted,
and deleted rows from a table and see:
INFO: free space map: 50 relations with free space, maximum of 1000
relations trackable
INFO: 17266 pages stored, 18016 pages used (with overhead)
INFO: 18784 pages required to store all freespace, maximum of 18000
pages allocatable (171 kB)
NOTICE: the number of page slots needed (18784) exceeds max_fsm_pages
(18000)
HINT: Consider increasing the configuration parameter "max_fsm_relations"
to a value over 18784.
The 'pages used' is greater than 18000, which isn't possible. Seems I
have more work to do.
--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073Import Notes
Reply to msg id not found: | Resolved by subject fallback
Bruce Momjian wrote:
pgman wrote:
INFO: free space map: 49 relations with free space, maximum of 1000 relations trackable
INFO: 17266 pages stored, 18000 pages used (with overhead)
INFO: 18768 pages required to store all freespace, maximum of 18000 pages allocatable (171 kB)
NOTICE: the number of page slots needed (18768) exceeds max_fsm_pages (18000)
HINT: Consider increasing the configuration parameter "max_fsm_relations"
to a value over 18768.I find this output cleaner and easier to understand. The "pages used"
value will match either the "required" or "maximum" value on the line
below.The "pages used" sentence above is wrong, and it seems the computation
is wrong too. I just connected to another database, created, inserted,
and deleted rows from a table and see:INFO: free space map: 50 relations with free space, maximum of 1000
relations trackable
INFO: 17266 pages stored, 18016 pages used (with overhead)
INFO: 18784 pages required to store all freespace, maximum of 18000
pages allocatable (171 kB)
NOTICE: the number of page slots needed (18784) exceeds max_fsm_pages
(18000)
HINT: Consider increasing the configuration parameter "max_fsm_relations"
to a value over 18784.The 'pages used' is greater than 18000, which isn't possible. Seems I
have more work to do.
OK, I have simplified the patch. It doesn't use any new computations
but just displays them differently. The output is now:
INFO: free space map contains information about:
INFO: 49 relations, limit 1000 relations
INFO: 35 pages with free space, 784 pages (with overhead)
INFO: 784 pages required to track all freespace, limit 18000 pages (171 kB)
I have committed this patch to HEAD.
--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073Attachments:
/bjm/difftext/plainDownload+20-19
Bruce Momjian <pgman@candle.pha.pa.us> writes:
OK, I have simplified the patch. It doesn't use any new computations
but just displays them differently. The output is now:
INFO: free space map contains information about:
INFO: 49 relations, limit 1000 relations
INFO: 35 pages with free space, 784 pages (with overhead)
INFO: 784 pages required to track all freespace, limit 18000 pages (171 kB)
This breaks the message style guidelines in a number of ways, and I
don't find it clear at all.
regards, tom lane
Tom Lane wrote:
Bruce Momjian <pgman@candle.pha.pa.us> writes:
OK, I have simplified the patch. It doesn't use any new computations
but just displays them differently. The output is now:INFO: free space map contains information about:
INFO: 49 relations, limit 1000 relations
INFO: 35 pages with free space, 784 pages (with overhead)
INFO: 784 pages required to track all freespace, limit 18000 pages (171 kB)This breaks the message style guidelines in a number of ways, and I
don't find it clear at all.
OK, what suggestions do you have, and how did I break the style
guidelines?
--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073