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https://issues.apache.org/jira/browse/IGNITE-425?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16162741#comment-16162741
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Nikolay Izhikov commented on IGNITE-425:
----------------------------------------
Hello, [~yzhdanov]
> Given we cannot distinguish newly created entry and one that existed before
> query
We can distinguish create and update operation in filter and transformer.
We can pass that knowledge further to listener if we want to.
ContinuousQueryWithTransformer.java
{code:java}
public Factory<? extends IgniteClosure<CacheEntryEvent<? extends K, ?
extends V>, T>> getRemoteTransformerFactory() {
return rmtTransFactory;
}
{code}
CacheEntryEventFilter.java
{code:java}
public interface CacheEntryEventFilter<K, V> {
boolean evaluate(CacheEntryEvent<? extends K, ? extends V> event)
throws CacheEntryListenerException;
}
{code}
CacheEntryEvent.java
{code:java}
public abstract class CacheEntryEvent<K, V> extends EventObject implements
Cache.Entry<K, V> {
public final EventType getEventType() {
return eventType;
}
}
{code}
> should we just remove it?
In my implementation, I try to minimize a difference between regular
ContinuousQuery and ContinuousQueryWithTransformer.
I think it useful from user experience point of view.
> Introduce transformers for continuous queries
> ---------------------------------------------
>
> Key: IGNITE-425
> URL: https://issues.apache.org/jira/browse/IGNITE-425
> Project: Ignite
> Issue Type: Sub-task
> Components: cache
> Reporter: Yakov Zhdanov
> Assignee: Nikolay Izhikov
>
> Currently if updated entry passes the filter, it is sent to node initiated
> the query entirely. It would be good to provide user with the ability to
> transform entry and, for example, select only fields that are important. This
> may bring huge economy to traffic and lower GC pressure as well.
> Possible signatures will be:
> {noformat}
> public final class ContinuousQuery<K, V, T> {..} // T is a type transformer
> transforms to
> public ContinuousQuery<K, V, T> setLocalListener(Listener<T> locLsnr) {..} //
> Probably, we will have to introduce new listener type, since user may want to
> wipe out key as well.
> /* new method to add */
> public ContinuousQuery<K, V, T> setRemoteTransformerFactory(Factory<? extends
> ContinuousQueryTransformer<K, V, T>> factory) { ..}
> {noformat}
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