Github user jessehatfield commented on a diff in the pull request:
https://github.com/apache/incubator-rya/pull/254#discussion_r160811757
--- Diff:
dao/mongodb.rya/src/main/java/org/apache/rya/mongodb/aggregation/AggregationPipelineQueryOptimizer.java
---
@@ -0,0 +1,67 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.rya.mongodb.aggregation;
+
+import org.apache.hadoop.conf.Configurable;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.rya.mongodb.StatefulMongoDBRdfConfiguration;
+import org.openrdf.query.BindingSet;
+import org.openrdf.query.Dataset;
+import org.openrdf.query.algebra.TupleExpr;
+import org.openrdf.query.algebra.evaluation.QueryOptimizer;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * MongoDB-specific query optimizer that replaces part or all of a SPARQL
query
+ * tree with a MongoDB aggregation pipeline.
+ * <p>
+ * Transforms query trees using {@link SparqlToPipelineTransformVisitor}.
If
+ * possible, this visitor will replace portions of the query tree, or the
entire
+ * query, with an equivalent aggregation pipeline (contained in an
+ * {@link AggregationPipelineQueryNode}), thereby allowing query logic to
be
+ * evaluated by the MongoDB server rather than by the client.
+ */
+public class AggregationPipelineQueryOptimizer implements QueryOptimizer,
Configurable {
+ private Configuration conf;
+ private Logger logger = LoggerFactory.getLogger(getClass());
+
+ @Override
+ public void optimize(TupleExpr tupleExpr, Dataset dataset, BindingSet
bindings) {
+ if (conf instanceof StatefulMongoDBRdfConfiguration) {
+ StatefulMongoDBRdfConfiguration mongoConf =
(StatefulMongoDBRdfConfiguration) conf;
+ SparqlToPipelineTransformVisitor pipelineVisitor = new
SparqlToPipelineTransformVisitor(mongoConf);
+ try {
+ tupleExpr.visit(pipelineVisitor);
+ } catch (Exception e) {
+ logger.error("Error attempting to transform query using
the aggregation pipeline", e);
+ }
+ }
+ }
+
+ @Override
+ public void setConf(Configuration conf) {
+ this.conf = conf;
--- End diff --
Agreed, fixed.
---
