Indexing PDF documents in Solr with no UniqueKey - lucene

Question

I want to index PDF (and other rich) documents. I am using the DataImportHandler.
Here is how my schema.xml looks:
.........
.........
<field name="title" type="text" indexed="true" stored="true" multiValued="false"/>
<field name="description" type="text" indexed="true" stored="true" multiValued="false"/>
<field name="date_published" type="string" indexed="false" stored="true" multiValued="false"/>
<field name="link" type="string" indexed="true" stored="true" multiValued="false" required="false"/>
<dynamicField name="attr_*" type="textgen" indexed="true" stored="true" multiValued="false"/>
........
........
<uniqueKey>link</uniqueKey>
As you can see I have set link as the unique key so that when the indexing happens documents are not duplicated again. Now I have the file paths stored in a database and I have set the DataImportHandler to get a list of all the file paths and index each document. To test it I used the tutorial.pdf file that comes with example docs in Solr. The problem is of course this pdf document won't have a field 'link'. I am thinking of way how I can manually set the file path as link when indexing these documents. I tried the data-config settings as below,
<entity name="fileItems" rootEntity="false" dataSource="dbSource" query="select path from file_paths">
<entity name="tika-test" processor="TikaEntityProcessor" url="${fileItems.path}" dataSource="fileSource">
<field column="title" name="title" meta="true"/>
<field column="Creation-Date" name="date_published" meta="true"/>
<entity name="filePath" dataSource="dbSource" query="SELECT path FROM file_paths as link where path = '${fileItems.path}'">
<field column="link" name="link"/>
</entity>
</entity>
</entity>
where I create a sub-entity which queries for the path name and makes it return the results in a column titled 'link'. But I still see this error:
WARNING: Error creating document : SolrInputDocument[{date_published=date_published(1.0)={2011-06-23T12:47:45Z}, title=title(1.0)={Solr tutorial}}]
org.apache.solr.common.SolrException: Document is missing mandatory uniqueKey field: link
Is there anyway for me to create a field called link for the pdf documents?
This was already asked here before but the solution provided uses ExtractRequestHandler but I want to use it through the DataImportHandler.

Answer 1

Try this:
<entity name="fileItems" rootEntity="false" dataSource="dbSource" query="select path from file_paths">
<field column="path" name="link"/>
<entity name="tika-test" processor="TikaEntityProcessor" url="${fileItems.path}" dataSource="fileSource">
<field column="title" name="title" meta="true"/>
<field column="Creation-Date" name="date_published" meta="true"/>
</entity>
</entity>