How to select shard for search query? - hibernate-search

Question

I'm recently implemented ShardIdentifierProvider. It is working fine. But how to ensure it is using only one shared for query?
public class SiteIdAsShardIdProvider extends ShardIdentifierProviderTemplate {
#Override
protected Set<String> loadInitialShardNames(Properties properties, BuildContext buildContext) {
ServiceManager serviceManager = buildContext.getServiceManager();
SessionFactory sessionFactory = serviceManager.requestService(HibernateSessionFactoryServiceProvider.class, buildContext);
Session session = sessionFactory.openSession();
try {
#SuppressWarnings("unchecked")
List<String> ids = session.createSQLQuery("select cast(id as CHAR(3)) from website").list();
return new HashSet<>(ids);
} finally {
session.close();
}
}
#Override
public String getShardIdentifier(Class<?> entityType, Serializable id, String idAsString, Document document) {
return document.getFieldable("siteId").stringValue();
}
}

Answer 1

Creating your own custom filter and overriding getShardIdentifiersForQuery should do the trick. Here is something that does approximately the same as what's in the documentation, but with a ShardIdentifierProviderTemplate:
#Override
public Set<String> getShardIdentifiersForQuery(FullTextFilterImplementor[] filters) {
FullTextFilter filter = getFilterByName( filters, "customer" );
if ( filter == null ) {
return getAllShardIdentifiers();
}
else {
Set<String> result = new HashSet<>();
result.add( filter.getParameter( "customerID" ) );
return result;
}
}
private FullTextFilter getFilterByName(FullTextFilterImplementor[] filters, String name) {
for ( FullTextFilterImplementor filter: filters ) {
if ( filter.getName().equals( name ) ) {
return filter;
}
}
return null;
}
I created a ticket to update the documentation: https://hibernate.atlassian.net/browse/HSEARCH-2513

Answer 2

The shard selection at query time is controlled by using a custom Filter.
See "5.3.1. Using filters in a sharded environment" for details and examples.