Unfortunately, update processors only "see" the new, fresh, incoming data,
not any existing document data.
This is a case where your best bet may be to read the document first and
then merge your new value into the existing list of values.
-- Jack Krupansky
-----Original Message-----
From: tuedel
Sent: Monday, July 01, 2013 9:34 AM
To: solr-user@lucene.apache.org
Subject: Distinct values in multivalued fields
Hello everybody,
i have tried to make use of the UniqFieldsUpdateProcessorFactory in
order to achieve distinct values in multivalued fields. Example below:
<updateRequestProcessorChain name="uniq_fields">
<processor
class="org.apache.solr.update.processor.UniqFieldsUpdateProcessorFactory">
<lst name="fields">
<str>title</str>
<str>tag_type</str>
</lst>
</processor>
<processor class="solr.RunUpdateProcessorFactory" />
</updateRequestProcessorChain>
<requestHandler name="/update" class="solr.UpdateRequestHandler">
<lst name="defaults">
<str name="update.chain">uniq_fields</str>
</lst>
</requestHandler>
However the data being is indexed one by one. This may happen, since a
document may will get an additional tag in a future update. Unfortunately in
order to ensure not having any duplicate tags, i was hoping, the
UpdateProcessorFactory is doing what i want to achieve. In order to actually
add a tag, i am sending an
"tag_type" :{"add":"foo"}, which still adds the tag, without questioning if
its already part of the field. How may i be able to achieve distinct values
on solr side?!
In order to achieve this behavior i suggest writing an own processor might
be a solution. However i am uncertain how to do and if it's the proper way.
Imagine an incoming update - e.g. an update of an existing document having
several multivalued fields without specifying "add" or "set". This task
would cause the corresponding document to get dropped and re-indexed without
keeping any previously added values within the multivalued field.
Therefore if a field is getting updated and not having the distinct value
being part of the index yet, shall add the value, otherwise ignore it. The
processor needs to define whether a field is getting added to the index or
not in condition of the existing index. Is that achievable on Solr side?!
Below my current pretty empty processor class:
public class ConditionalSolrUniqFieldValuesProcessorFactory extends
UpdateRequestProcessorFactory {
@Override
public UpdateRequestProcessor getInstance(SolrQueryRequest sqr,
SolrQueryResponse sqr1, UpdateRequestProcessor urp) {
return new ConditionalUniqFieldValuesProcessor(urp);
}
class ConditionalUniqFieldValuesProcessor extends UpdateRequestProcessor
{
public ConditionalUniqFieldValuesProcessor(UpdateRequestProcessor
next) {
super(next);
}
@Override
public void processAdd(AddUpdateCommand cmd) throws IOException {
SolrInputDocument doc = cmd.getSolrInputDocument();
Collection<String> incomingFieldNames = doc.getFieldNames();
for (String t : incomingFieldNames) {
/*
is multivalued
if (doc.getField(t).) {
If multivalued and already part of index, drop from
index. Otherwise add to multivalued field.
}
*/
}
}
}
}
--
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