Executing a relational query

Example – Using retrieval policies
//create a new retrieval policy:

			RetrievalPolicy retrievalPolicy = new RetrievalPolicy();

			

			//use fastest available source of data:

			retrievalPolicy.setPolicyValue(RetrievalPolicy.FASTEST);

			

			//configure to acquire new connections always:

			retrievalPolicy.getConnectionConfiguration().setConnectionLifetime(

			

			ConnectionConfiguration.ACQUIRE_RELEASE);

			

			//create a QueryConnector for executing queries:

			QueryConnector queryConnector = new QueryConnector();

			

			//set the query connector's default retrieval 
			policy:

			queryConnector.setRetrievalPolicy(retrievalPolicy);

			

			//build a query:

			BusinessQuery query1 = buildRelationalBusinessQuery();

			

			//execute the query using the default retrieval 
			policy:

			Map results = 

			queryConnector.retrieveQueryResultMap(Collections.singletonList(query1));

			

			//make a copy of the old policy:

			RetrievalPolicy connectionRecyclingPolicy = new RetrievalPolicy(retrievalPolicy);

			

			//make the copied policy re-use connections:
			

			connectionRecyclingPolicy.getConnectionConfiguration().setConnectionLifetime(

			ConnectionConfiguration.USER_SESSION);

			

			//execute the query again, using the new retrieval 
			policy

			//(overriding the default for this call only):

			Map moreResults =

			queryConnector.retrieveQueryResultMap(

			Collections.singletonList(query1),

			connectionRecyclingPolicy);

			

			//close the result sets just retrieved and the 
			server connection:

			int closeConnectionAndResultSet =

			QueryConnector.CloseOptions.ALL_RESULTSET_OPTIONS

			| QueryConnector.CloseOptions.ALL_CONNECTION_OPTIONS;

			

			queryConnector.closeResources(getSessionContext(), closeConnectionAndResultSet);