[check_postgres] Problems with check_bloat
Luis Vazquez
luis at asterisk.uy
Tue Jul 21 16:35:56 UTC 2015
Hi Greg,
I've trying to use the check_BLOAT action and I've found many problems.
* In first place the check seems to work (mostly) OK when I put a size
value in the warning and/or critical options, but will allways git a
CRITICAL output if I pass percentages. Here is a sample output showing
both cases:
With sizes values: OK:
$ ./check_postgres.pl --host 172.16.200.71 --dbservice=nagios
--showtime=1 --action=bloat --db=XXXX --warning='50M' --critical='100M'
--perflimit 5
*POSTGRES_BLOAT OK:* service=nagios (host:172.16.200.71) (db XXXX) table
public.ir_translation rows:43329 pages:1178 shouldbe:877 (1.3X) *wasted
size:2465792 (2 MB)* | public.ir_translation=2465792B
ir_translation_comments_index=0B ir_translation_ltn=0B
ir_translation_module_index=0B ir_translation_res_id_index=0B
With percentage values: CRITICAL => wrong:
./check_postgres.pl --host 172.16.200.71 --dbservice=nagios
--action=bloat --db=XXXX --warning='80%' --critical='90%' --perflimit 5
*POSTGRES_BLOAT **CRITICAL:* service=nagios (host:172.16.200.71) (db
XXXX) table public.ir_translation rows:43329 pages:1178 shouldbe:877
(1.3X) *wasted size:2465792 (2 MB)* | public.ir_translation=2465792B
ir_translation_comments_index=0B ir_translation_ltn=0B
ir_translation_module_index=0B ir_translation_res_id_index=0B*
*Motivated from this I started looking the code trying to figure out the
problem.
I still haven't found how to fix it, but in the meantime I'have found
some other details that seems wrong to me:
* The function check_bloat uses two hardcoded variables $MINPAGES and
$MINIPAGES that seems to be the minimum pages for a table or an index to
be taken into account.
**Playing with those values I've found some code that is really cryptic
(and I thing is a bug) when you check the result of the select returned
from the run_command() to see if you have an empty result set.
Here you are using an scalar matching operator
(http://mkweb.bcgsc.ca/intranet/perlbook/prog/ch05_02.htm) to check for
a non empty value in an array o maps object ($db->{slurp}).
** LINE: 3905 **
$db = $info->{db}[0];
if (*$db->{slurp} !~ /\w+/o*) {
add_ok msg('bloat-nomin') unless $MRTG;
return;
}
The referred message is 'bloat-nomin'=> q{no relations meet the minimum
bloat criteria},
When I increase the values of $MINPAGES/$MINIPAGES so there are no
results in the select, $db->{slurp} is an empty array reference but the
if condition keeps giving false because you are matching against the
string representation of the reference, something like: ARRAY(0x24daec0).
I have verified that in the run_command() function you make sure to
return an array: $db->{slurp} = \@stuff
So to check for no results, I think you should instead check for an
undefined (to be on the safe side) or an empty array reference with
something like this:
if (!defined(*$db->{slurp}*) || @*$db->{slurp}* == 0) {
add_ok msg('bloat-nomin') unless $MRTG;
return;
}
* The final point is just a detail and not a big concern; but I see the
default for MINIPAGES is 10 but the default for MINPAGES is 0 which
doen't make many sense to me. I think both default values should be
positive and they should be taken as optional parameters; and even
default to the same value if only the --minpages option is given. I'm
offering myself to implement this if you agree to include these changes.
Best regards
Luis
--
------------------------------------------------------------------------
"Las ideas no duran mucho, hay que hacer algo con ellas"
~ Santiago Ramón y Cajal
<http://es.wikipedia.org/wiki/Santiago_Ram%C3%B3n_y_Cajal>
------------------------------------------------------------------------
Ing. Luis Vazquez - AsteriskUY Soluciones Corporativas
Comunicación VoIP y Soluciones IT Open Source
Elastix Certified Engineer
------------------------------------------------------------------------
Lauro Muller 1888 Ap. 201
CP: 11300 | Montevideo, Uruguay
Tel: 099117751 | luis at asterisk.uy <mailto:luis at asterisk.org.uy> Linux
<http://www.linux.org> GNU <http://www.gnu.org> Asterisk
<http://www.asterisk.org> Elastix <http://www.elastix.com> Centreon
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