Github user moshebla commented on a diff in the pull request:
https://github.com/apache/lucene-solr/pull/416#discussion_r213270075
--- Diff:
solr/core/src/java/org/apache/solr/response/transform/ChildDocTransformer.java
---
@@ -0,0 +1,263 @@
+/*
+ * 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.solr.response.transform;
+
+import java.io.IOException;
+import java.lang.invoke.MethodHandles;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import com.google.common.collect.ArrayListMultimap;
+import com.google.common.collect.Multimap;
+import org.apache.lucene.index.DocValues;
+import org.apache.lucene.index.LeafReaderContext;
+import org.apache.lucene.index.ReaderUtil;
+import org.apache.lucene.index.SortedDocValues;
+import org.apache.lucene.search.join.BitSetProducer;
+import org.apache.lucene.util.BitSet;
+import org.apache.solr.common.SolrDocument;
+import org.apache.solr.search.DocSet;
+import org.apache.solr.search.SolrDocumentFetcher;
+import org.apache.solr.search.SolrIndexSearcher;
+import org.apache.solr.search.SolrReturnFields;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import static
org.apache.solr.response.transform.ChildDocTransformerFactory.NUM_SEP_CHAR;
+import static
org.apache.solr.response.transform.ChildDocTransformerFactory.PATH_SEP_CHAR;
+import static org.apache.solr.schema.IndexSchema.NEST_PATH_FIELD_NAME;
+
+class ChildDocTransformer extends DocTransformer {
+ private static final Logger log =
LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
+
+ private static final String ANON_CHILD_KEY = "_childDocuments_";
+
+ private final String name;
+ private final BitSetProducer parentsFilter;
+ private final DocSet childDocSet;
+ private final int limit;
+ private final boolean isNestedSchema;
+
+ private final SolrReturnFields childReturnFields = new
SolrReturnFields();
+
+ ChildDocTransformer(String name, BitSetProducer parentsFilter,
+ DocSet childDocSet, boolean isNestedSchema, int
limit) {
+ this.name = name;
+ this.parentsFilter = parentsFilter;
+ this.childDocSet = childDocSet;
+ this.limit = limit;
+ this.isNestedSchema = isNestedSchema;
+ }
+
+ @Override
+ public String getName() {
+ return name;
+ }
+
+ @Override
+ public void transform(SolrDocument rootDoc, int rootDocId) {
+ // note: this algorithm works if both if we have have _nest_path_ and
also if we don't!
+
+ try {
+
+ // lookup what the *previous* rootDocId is, and figure which segment
this is
+ final SolrIndexSearcher searcher = context.getSearcher();
+ final List<LeafReaderContext> leaves =
searcher.getIndexReader().leaves();
+ final int seg = ReaderUtil.subIndex(rootDocId, leaves);
+ final LeafReaderContext leafReaderContext = leaves.get(seg);
+ final int segBaseId = leafReaderContext.docBase;
+ final int segRootId = rootDocId - segBaseId;
+ final BitSet segParentsBitSet =
parentsFilter.getBitSet(leafReaderContext);
+
+ final int segPrevRootId = segRootId==0? -1:
segParentsBitSet.prevSetBit(segRootId - 1); // can return -1 and that's okay
+
+ if(segPrevRootId == (segRootId - 1)) {
+ // doc has no children, return fast
+ return;
+ }
+
+ // we'll need this soon...
+ final SortedDocValues segPathDocValues =
DocValues.getSorted(leafReaderContext.reader(), NEST_PATH_FIELD_NAME);
+ // passing a different SortedDocValues obj since the child documents
which come after are of smaller docIDs,
+ // and the iterator can not be reversed.
+ final String transformedDocPath = getPathByDocId(segRootId,
DocValues.getSorted(leafReaderContext.reader(), NEST_PATH_FIELD_NAME));
+
+ // the key in the Map is the document's ancestors key(one above the
parent), while the key in the intermediate
+ // MultiMap is the direct child document's key(of the parent
document)
+ Map<String, Multimap<String, SolrDocument>>
pendingParentPathsToChildren = new HashMap<>();
+
+ SolrDocumentFetcher docFetcher = searcher.getDocFetcher();
+ final int lastChildId = segBaseId + segPrevRootId + 1;
+ // Loop each child ID up to the parent (exclusive).
+ for (int docId = calcDocIdToIterateFrom(lastChildId, rootDocId);
docId < rootDocId; ++docId) {
+
+ // get the path. (note will default to ANON_CHILD_KEY if schema
is not nested or empty string if blank)
+ String fullDocPath = getPathByDocId(docId - segBaseId,
segPathDocValues);
+
+ if(isNestedSchema && !fullDocPath.contains(transformedDocPath)) {
--- End diff --
Perhaps a better way to do this would be building a new Filter for every
transformed doc e.g. `_nest_path_:transformedDocPath`?
I am not quite sure of the performance overhead such technique would impose,
WDYT?
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