RE: Native compiled code *much* slower??
- From: "Mark W. Farnham" <mwf@xxxxxxxx>
- To: <stbaldwin@xxxxxxxxxxxxxxxx>, "'Toon Koppelaars'" <toon.koppelaars@xxxxxxxxxxx>
- Date: Thu, 24 Dec 2009 09:21:36 -0500
Without knowing what you are doing, we cannot know whether we are evaluating
the same execution path on the same data.
For example, your script could be looping arbitrary long until there is a
row to process found in some table, and some asynchronous event could be
putting rows in that table. Now while I doubt you would submit something
intentionally misleading, we often do not see subtle equivalents to this
case in our own code. I (and many before me) call this "code blindness" and
it is remarkably common and is often the underlying reason why simply
explaining your problem to someone else can solve the problem.
Now, barring a bug, I believe it is true that PL/SQL things like
if-then-else, math, loops and the like all have a chance with native to be
faster than interpreted and that calls into the database engine to get data
should be equivalent.
Bryn Llwellyn (sp?) presented some examples of code running significantly
faster native at both Collaborate and OOW. I have not done any serious
benchmarking.
Spewing your sample code at the list as per Toon's request might be useful.
Since he often yields substantial improvements back when folks asking for
help comply with his information requests, I know that in addition to asking
why it could make a difference (which I'm not sure is a genuine question in
your case), I'd be showing my code to him. I always allow for the
possibility that I'm doing something really stupid and that someone else
will see the problem immediately without much fuss. Embarassing, maybe, but
usually productive, even if it just yields a shift from wondering what to
focus on the actual problem.
Showing the code might also reference something that is a known problem. I
unfortunately do not know of any current "called by native compiled
problems," but I haven't looked.
Summary: Even without changing from native to interpreted the same code
could run very differently from run to run. Yes, I've seen what appear to be
valid reports of native running much faster.
Good luck. mwf
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Steve Baldwin
Sent: Thursday, December 24, 2009 3:10 AM
To: Toon Koppelaars
Cc: oracle-l@xxxxxxxxxxxxx
Subject: Re: Native compiled code *much* slower??
Hi Toon,
Should it matter? I thought that *everything* was at least as fast
native compiled. From the Oracle docs ...
"Because native compilation applies only to PL/SQL statements, a
PL/SQL unit that only calls SQL statements might not run faster when
natively compiled, but it does run at least as fast as the
corresponding interpreted code. The compiled code and the interpreted
code make the same library calls, so their action is the same."
I have tried a trivial package and the natively compiled package was
marginally faster than interpreted however the package I'm testing
here is pretty much all PL/SQL code so I expected it to be
significantly faster, not 100x *slower*.
I guess now it's a matter of trying to pull it apart to find out what
is causing the slowdown.
Has anyone seen significant improvement using native compilation?
Thanks,
Steve
On Thu, Dec 24, 2009 at 6:48 PM, Toon Koppelaars
<toon.koppelaars@xxxxxxxxxxx> wrote:
> What's in: msc$log_p?
> And in sb2.sql?
>
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