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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_r159307946 --- Diff: dao/mongodb.rya/src/main/java/org/apache/rya/mongodb/aggregation/SparqlToPipelineTransformVisitor.java --- @@ -0,0 +1,151 @@ +/* + * 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 java.util.Arrays; + +import org.apache.rya.mongodb.MongoConnectorFactory; +import org.apache.rya.mongodb.MongoDBRdfConfiguration; +import org.bson.Document; +import org.openrdf.query.algebra.Distinct; +import org.openrdf.query.algebra.Extension; +import org.openrdf.query.algebra.Filter; +import org.openrdf.query.algebra.Join; +import org.openrdf.query.algebra.MultiProjection; +import org.openrdf.query.algebra.Projection; +import org.openrdf.query.algebra.Reduced; +import org.openrdf.query.algebra.StatementPattern; +import org.openrdf.query.algebra.helpers.QueryModelVisitorBase; + +import com.mongodb.MongoClient; +import com.mongodb.client.MongoCollection; +import com.mongodb.client.MongoDatabase; + +public class SparqlToPipelineTransformVisitor extends QueryModelVisitorBase<Exception> { + private MongoCollection<Document> inputCollection; + + public SparqlToPipelineTransformVisitor(MongoCollection<Document> inputCollection) { + this.inputCollection = inputCollection; --- End diff -- Is this allowed to be null? > 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. -- This message was sent by Atlassian JIRA (v6.4.14#64029)