Re: Expanding Import
Re: Expanding Import
- Subject: Re: Expanding Import
- From: Chuck Hill <email@hidden>
- Date: Tue, 7 Mar 2006 15:00:08 -0800
On Mar 7, 2006, at 2:46 PM, Scott Winn wrote:
Thanks for the response Chuck.
The solution, is to not include this relationship in your model or
to not make it a class property. In most cases like this, you
really don't need this relationship or seldom need it. In this
case you can mimic it by fetching the related objects when needed.
So what I need to be doing is
1) Remove the offending relationships from the entity's Class
properties
Or remove them entirely if you don't need them for delete rules.
2) Make my foreign key fields (in the formerly related entity)
Class Properties
3) Use primaryKeyForObject to set the relationship in the foreign
key by hand (as it were)
Um, no. If you don't have the relationship, there is no need to set
it. I may misunderstand your model. What I understand is that you
have two, reciprocal relationships, Certificate ->> Stations and
Station ->> Certificates. If you don't need the Station ->>
Certificates relationship (but do need the Certificate ->> Stations
one), you can just eliminate it. What are you describing is a
symptom of updating a very large to-many relationship. If you don't
need the relationship, removing it will dramatically speed things up.
Your description has left me rather confused as to details of what
you are doing and it is hard for me to see what, if anything, can be
eliminated. Perhaps you can try to describe the relationships and
process again. It may also be that Anjo's solution is the answer to
your problem.
Is that right or is there a better approach? I am very new to
WebObjects and Java to boot. I have been trying hard to do things
the WO Way, but this project seems determined to make me learn WO
from the inside out.
Grin.
Chuck
On Mar 7, 2006, at 2:20 PM, Chuck Hill wrote:
Hi Scott,
On Mar 7, 2006, at 1:49 PM, Scott Winn wrote:
Hello List,
I am working on a fixed-width record importer for my database. I
have to interface with a legacy app, so there is no getting out
of it.
My WO importer app has significant performance issues. The CPU
is very busy, memory usage is high, and the database has hardly
any load on it. I have increased my JVM size, I ec.dispose() and
get a new EC periodically, and I run garbage collection after
every imported file. I don't get out of memory errors anymore,
but after importing a few months worth of data the app runs so
slow that it might as well be stopped.
As I read the files, I get codes for an Entity like NCStation,
for example. Then I check for a match on stationCode in the
database using a fetchSpec, create it if it doesn't exist, and
add it to the appropriate relationship to a Certificate in this
case. To see what is going on, I called ec.updatedObjects() just
before an ec.saveChanges() and I got something like this. . .
values = {
stationCode = "199";
stationDescription = <com.webobjects.foundation.NSKeyValueCoding
$Null>;
Certificates = (
--> "<NCCertificate b94a3f _EOIntegralKeyGlobalID[Certificate
(java.lang.Integer)1]>",
--> "<NCCertificate b9ae95 _EOIntegralKeyGlobalID[Certificate
(java.lang.Integer)2]>",
--> "<NCCertificate 74c043 _EOIntegralKeyGlobalID[Certificate
(java.lang.Integer)3]>",
--> "<NCCertificate faa3c5 _EOIntegralKeyGlobalID[Certificate
(java.lang.Integer)4]>",
--> "<NCCertificate 15ebf0 _EOIntegralKeyGlobalID[Certificate
(java.lang.Integer)5]>",
"<NCCertificate 75deb1 <EOTemporaryGlobalID: 0 0 -64 -88 42 -3
0 0 -60 50 22 0 0 0 1 9 -73 45 -46 -91 86 -26 -122 58>>");
Company = "<NCCompany fc9484 _EOIntegralKeyGlobalID[Company
(java.lang.Integer)1]>";
stationName = <com.webobjects.foundation.NSKeyValueCoding$Null>;
};
this = "<NCStation 9096c6 _EOIntegralKeyGlobalID[Station
(java.lang.Integer)1]>";
The lines indicated with --> seem to just be along for the ride.
I don't need to make any changes to them. I don't want to make
any changes to the entity itself. All I want to do is add more
objects to the relationship. After two or three imported files,
my ec. updatedObjects() call is showing thousands of entries for
the "to-many" relationships. Obviously, it just gets worse the
more I import.
So my questions are these. . .
1) Is my diagnosis on the right track?
I think so.
2) What is the right way to approach something like this? Raw
Rows? Or would that make any difference?
It might, but you would have to form the relationships yourself.
And the big question. . .
3) How do I check the database for an Entity and relate an object
to it when there are potentially a million other objects related
to it?
I think, in a round about way, you have identified the problem. I
will hazard a guess that in your model you have a Certificate ->>
Stations. So as you add a certificate to a station, this reverse
relationship grows ever larger. The solution, is to not include
this relationship in your model or to not make it a class
property. In most cases like this, you really don't need this
relationship or seldom need it. In this case you can mimic it by
fetching the related objects when needed.
Chuck
--
Coming in 2006 - an introduction to web applications using
WebObjects and Xcode http://www.global-village.net/wointro
Practical WebObjects - for developers who want to increase their
overall knowledge of WebObjects or who are trying to solve
specific problems. http://www.global-village.net/products/
practical_webobjects
--
Coming in 2006 - an introduction to web applications using WebObjects
and Xcode http://www.global-village.net/wointro
Practical WebObjects - for developers who want to increase their
overall knowledge of WebObjects or who are trying to solve specific
problems. http://www.global-village.net/products/practical_webobjects
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