Re: How to avoid expensive fetches in database when setting to-one-relationship
Re: How to avoid expensive fetches in database when setting to-one-relationship
- Subject: Re: How to avoid expensive fetches in database when setting to-one-relationship
- From: Jérémy DE ROYER <email@hidden>
- Date: Sun, 05 Jun 2016 22:58:42 +0000
- Thread-topic: How to avoid expensive fetches in database when setting to-one-relationship
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In fact, I can understand that WebObjects fetches the orders of a customer when inserting a new order for this customer.
But I don’t understand why WebObjects fetches all the to many relationships of this customer ???? And how to tell WebObjects not to do it (;-)
That is what I meant by fetching. You need to re-implement those methods. Change it to do an fetch on Customer where modeTransport == this
You can still use it to fetch a ModeTransport based on “listOrder contains order”.
Chuck
From: Jérémy DE ROYER <email@hidden>
Date: Sunday, June 5, 2016 at 3:26 PM
To: Chuck Hill <email@hidden>
Cc: WebObjects-Dev <email@hidden>
Subject: Re: How to avoid expensive fetches in database when setting to-one-relationship
What do you mean with « you can still use it for fetching » ?
I removed the class property for the Customer to Order (but keeped the « listOrder » relationship)
When I set the customer to the order, it runs fast.
But when I retrieve the orders using the method below :
public NSArray<Customer> listOrder() {
return (NSArray<Customer>)storedValueForKey("listOrder");
<com.webobjects.foundation.NSKeyValueCoding$UnknownKeyException message
‘<Customer 0x72c7423b> valueForKey(): lookup of unknown key: 'listOrder'.
This class does not have an instance variable of the name listOrder or _listOrder, nor a method of the name listOrder _listOrder, getListOrder, or _getListOrder' object ‘{...}'
key 'listOrder'>
at com.webobjects.foundation.NSKeyValueCoding$DefaultImplementation.handleQueryWithUnboundKey(NSKeyValueCoding.java:1377)
at com.webobjects.eocontrol.EOCustomObject.handleQueryWithUnboundKey(EOCustomObject.java:1545)
at com.webobjects.foundation.NSKeyValueCoding$Utility.handleQueryWithUnboundKey(NSKeyValueCoding.java:494)
at com.webobjects.foundation.NSKeyValueCoding$_KeyBinding.valueInObject(NSKeyValueCoding.java:894)
at com.webobjects.eocontrol.EOCustomObject.storedValueForKey(EOCustomObject.java:1634)
at Customer.listeOrder(_Customer.java:890)
Remove the “class property” setting for the ModeTransport to Order. You can still use it for fetching.
In our app, we have a one to many relationship between order and mode transport
For each order, we set the mode transport using the method below :
public void setModeTransportRelationship(ModeTransport
value) {
if (_CommandeClient.LOG.isDebugEnabled())
{
_CommandeClient.LOG.debug("updating modeTransport from " +
modeTransport() + " to " + value);
ModeTransport oldValue = modeTransport();
removeObjectFromBothSidesOfRelationshipWithKey(oldValue, "modeTransport");
addObjectToBothSidesOfRelationshipWithKey(value, "modeTransport");
Then, an objectWillChange() is fired for the mode transport… but the (not wished) consequence is that every to many relationships from the mode transport are fetched (even if we don’t call the associated method for the mode transport). However,
the objects associated with the to one relationships are not fetched.
We observed the same behavior for the customer object when using the setCustomerRelationship method of the ordre. The (bigger) problem is that the customer object has dozen of to many relationships... fetched for nothing…
At the beginning we had few orders but now, we have to wait from 10 to 30 seconds until de saveChange is ended and that’s really not effective. More than 90 % of this time is spent for fetching the to many relationship whereas we just had to save the order
values...
Any idea how to deal with theses not-wished-fetches ?
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