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https://issues.apache.org/jira/browse/RYA-416?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16308650#comment-16308650
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ASF GitHub Bot commented on RYA-416:
------------------------------------
Github user kchilton2 commented on a diff in the pull request:
https://github.com/apache/incubator-rya/pull/254#discussion_r159306746
--- Diff:
dao/mongodb.rya/src/main/java/org/apache/rya/mongodb/aggregation/AggregationPipelineQueryOptimizer.java
---
@@ -0,0 +1,56 @@
+/*
+ * 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.log4j.Logger;
+import org.apache.rya.mongodb.MongoDBRdfConfiguration;
+import org.openrdf.query.BindingSet;
+import org.openrdf.query.Dataset;
+import org.openrdf.query.algebra.TupleExpr;
+import org.openrdf.query.algebra.evaluation.QueryOptimizer;
+
+public class AggregationPipelineQueryOptimizer implements QueryOptimizer,
Configurable {
+ private Configuration conf;
+ private Logger logger = Logger.getLogger(getClass());
+
+ @Override
+ public void optimize(TupleExpr tupleExpr, Dataset dataset, BindingSet
bindings) {
+ if (conf instanceof MongoDBRdfConfiguration) {
--- End diff --
This will likely change into a StatefulMongoDBRdfConfiguration in 414
(which is a MongoDBRdfConfiguration). Is anything about your optimizer
stateful? If so, you don't want to make more than one instance of it, so it
should be shared within that config.
> Add the ability use the MongoDB aggregation pipeline to evaluate simple
> SPARQL expressions
> ------------------------------------------------------------------------------------------
>
> Key: RYA-416
> URL: https://issues.apache.org/jira/browse/RYA-416
> Project: Rya
> Issue Type: New Feature
> Reporter: Jesse Hatfield
> Assignee: Jesse Hatfield
>
> MongoDB provides the [aggregation pipeline
> framework|https://docs.mongodb.com/manual/core/aggregation-pipeline/] for
> multi-stage data processing. Currently, the query engine invokes this
> framework to apply individual statement patterns (using a "$match" expression
> for each and iterating through the results), then applies higher-level query
> operations (join, filter, select, project, etc) client-side.
> In principle, those high-level query operations could be rewritten as
> aggregation pipeline stages as well ($group, $match, $project, etc). This
> would allow more query evaluation logic to be executed by the MongoDB server
> itself, enabling server-side optimization. This could be used as a general
> query optimization, but would additionally be useful for any tool that only
> needed to write query results back to the server: adding a write step to the
> end of the resulting pipeline could obviate the need to communicate
> individual results to the client at all.
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