Michael Shishcu wrote:
Hi everyone.
I did some research and found a strange thing. Hope I'm wrong, but...
It seems to me that when mapserver fetches data from the database, all
parameters for where clause of the query string (for example coordinates
for MDSYS.SDO_ORDINATE_ARRAY() procedure) are string literals and not
oracle's bind variables. This forces the DB to "hard parse" every query
from mapserver. But hard parse of the query is very CPU intensive
process, so data fetching is slower than it could be.
Can anyone confirm this, and if so, is there a workaround of such a problem?
Regards, Michael
Are you talking about preparing a query, like:
"select * from map where the_geom && ?"
and then executing the prepared query many-many times?
or are you talking about sending the arguments to a prepared query in
"binary" vs string format? (I know nothing about oracle, my terms are
Postgres, but I assume close)
If you are talking preparing once, and firing many-many times, then yes
it would be a speed up. But just the format the params are sent in, I
doubt would make a difference. Parsing a string like "30,40,50,60" into
an array [30, 40, 50, 60] should be very fast. (and besides, somebody
has to build the array, the time has to be spent somewhere, be it on the
client or the server).
Do you have any timing's to show the difference between the methods?
(I'm thinking like a perl script or something) Or any benchmarks on the
web someplace?
As for workaround, I would not think so. You'd probably have to get
your hands into the guts of mapserv and play around with the db
interface stuff.
-Andy
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