Hi Nandhita,
----- Original Message -----
> [...]
> I have been working on Oracle PMDA for a while now. I was able to make some
> changes to the source code and get the values printed out by Pmval (after
> referring to Postgresql PMDA) for all instances except sysstat.
Aha - it's great to hear that you're working on it and making progress too!
>
> select statistic# , value from v$sysstat;
>
> This SQL returns1178 rows of statistics, out of which 179 are listed as
> performance metrics in setup_sysstat .
>
> [...]
>
> I thought one way to extract a specific statictic# and itâs value is by using
> the $item number in sysstat_values sub.
Yeah, looking at the code, that's not going to work. The problem is the item
numbers (part of the PCP PMID, assigned at the call to add_metric() in setup()
routines) has no direct relation to the column (or row) in the SQL result.
We'll need to construct something to handle that. I see your code has acquired
several "map" arrays, like @latch_map and so on, to solve a similar problem.
In the v$sysstat case, I think we'll need to have a similar but different map.
Complicating the matter a bit is a statement on this page:
https://docs.oracle.com/cd/B28359_01/server.111/b28320/dynviews_3086.htm#i1420473
Which states: "Note: Statistics numbers are not guaranteed to remain constant
from one release to another. Therefore, you should rely on the statistics name
rather than its number in your applications."
This is a problem we need to deal with, because we were considering mapping item
number (from PCP PMID) to statistic number (from v$sysstat), or vice-versa, and
that cannot be done directly according to the above.
So, what I think is needed is a name -> item hash (instead of the column number
array, indexed by PMID item number) used when refreshing the other tables, as in
$latch_map for example. Attached is a patch to show the idea, not tested at all
and obviously would need to be updated for all of the v$sysstat metrics not just
the first 6. This patch applies to the PMDA code you sent through as your first
case (i.e. "1.pmdaoracle_mod_item.txt").
It looks like there is also a problem in handling the instance domain ($sid) in
the current pmdaoracle code; I've added a $sysstat_instances which I think will
be needed too (we have to hold the instance names and the @values in there - a
similar change will be needed for all $sid_instances uses I suspect) into that
patch, as well as an online reference to many of the stat names (V$STATNAME is
the definitive reference for the installed Oracle, AIUI).
Hope that all makes sense, and thanks again for starting to revive this code!
cheers.
--
Nathan
oracle-sysstat.patch
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