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Optimize sort on numeric long and date fields.
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This rewrites long sort as a `DistanceFeatureQuery`, which can
efficiently skip non-competitive blocks and segments of documents.
Depending on the dataset, the speedups can be 2 - 10 times.

The optimization can be disabled with setting the system property
`es.search.rewrite_sort` to `false`.

Optimization is skipped when an index has 50% or more data with
the same value.

Optimization is done through:
1. Rewriting sort as `DistanceFeatureQuery` which can
efficiently skip non-competitive blocks and segments of documents.

2. Sorting segments according to the primary numeric sort field(#44021)
This allows to skip non-competitive segments.

3. Using collector manager.
When we optimize sort, we sort segments by their min/max value.
As a collector expects to have segments in order,
we can not use a single collector for sorted segments.
We use collectorManager, where for every segment a dedicated collector
will be created.

4. Using Lucene's shared TopFieldCollector manager
This collector manager is able to exchange minimum competitive
score between collectors, which allows us to efficiently skip
the whole segments that don't contain competitive scores.

5. When index is force merged to a single segment, #48533 interleaving
old and new segments allows for this optimization as well,
as blocks with non-competitive docs can be skipped.

Closes #37043

Co-authored-by: Jim Ferenczi <jim.ferenczi@elastic.co>
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@mayya-sharipova @jimczi
mayya-sharipova and jimczi committed Nov 26, 2019
1 parent e9ba252 commit fa8b48d
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Showing 12 changed files with 767 additions and 297 deletions.
3 changes: 3 additions & 0 deletions buildSrc/src/main/groovy/org/elasticsearch/gradle/BuildPlugin.groovy
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Original file line number Diff line number Diff line change
Expand Up @@ -720,6 +720,9 @@ class BuildPlugin implements Plugin<Project> {
// TODO: remove this once ctx isn't added to update script params in 7.0
test.systemProperty 'es.scripting.update.ctx_in_params', 'false'

// TODO: remove this property in 8.0
test.systemProperty 'es.search.rewrite_sort', 'true'

// TODO: remove this once cname is prepended to transport.publish_address by default in 8.0
test.systemProperty 'es.transport.cname_in_publish_address', 'true'

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61 changes: 20 additions & 41 deletions docs/reference/search/profile.asciidoc
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Original file line number Diff line number Diff line change
Expand Up @@ -153,16 +153,9 @@ The API returns the following result:
"rewrite_time": 51443,
"collector": [
{
"name": "CancellableCollector",
"reason": "search_cancelled",
"time_in_nanos": "304311",
"children": [
{
"name": "SimpleTopScoreDocCollector",
"reason": "search_top_hits",
"time_in_nanos": "32273"
}
]
"name": "SimpleTopScoreDocCollector",
"reason": "search_top_hits",
"time_in_nanos": "32273"
}
]
}
Expand Down Expand Up @@ -445,16 +438,9 @@ Looking at the previous example:
--------------------------------------------------
"collector": [
{
"name": "CancellableCollector",
"reason": "search_cancelled",
"time_in_nanos": "304311",
"children": [
{
"name": "SimpleTopScoreDocCollector",
"reason": "search_top_hits",
"time_in_nanos": "32273"
}
]
"name": "SimpleTopScoreDocCollector",
"reason": "search_top_hits",
"time_in_nanos": "32273"
}
]
--------------------------------------------------
Expand Down Expand Up @@ -657,33 +643,26 @@ The API returns the following result:
"rewrite_time": 7208,
"collector": [
{
"name": "CancellableCollector",
"reason": "search_cancelled",
"time_in_nanos": 2390,
"name": "MultiCollector",
"reason": "search_multi",
"time_in_nanos": 1820,
"children": [
{
"name": "MultiCollector",
"reason": "search_multi",
"time_in_nanos": 1820,
"name": "FilteredCollector",
"reason": "search_post_filter",
"time_in_nanos": 7735,
"children": [
{
"name": "FilteredCollector",
"reason": "search_post_filter",
"time_in_nanos": 7735,
"children": [
{
"name": "SimpleTopScoreDocCollector",
"reason": "search_top_hits",
"time_in_nanos": 1328
}
]
},
{
"name": "MultiBucketCollector: [[my_scoped_agg, my_global_agg]]",
"reason": "aggregation",
"time_in_nanos": 8273
"name": "SimpleTopScoreDocCollector",
"reason": "search_top_hits",
"time_in_nanos": 1328
}
]
},
{
"name": "MultiBucketCollector: [[my_scoped_agg, my_global_agg]]",
"reason": "aggregation",
"time_in_nanos": 8273
}
]
}
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128 changes: 86 additions & 42 deletions server/src/main/java/org/elasticsearch/search/internal/ContextIndexSearcher.java
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,7 @@
import org.apache.lucene.search.CollectionStatistics;
import org.apache.lucene.search.CollectionTerminatedException;
import org.apache.lucene.search.Collector;
import org.apache.lucene.search.CollectorManager;
import org.apache.lucene.search.ConjunctionDISI;
import org.apache.lucene.search.DocIdSetIterator;
import org.apache.lucene.search.Explanation;
Expand All @@ -35,24 +36,31 @@
import org.apache.lucene.search.Query;
import org.apache.lucene.search.QueryCache;
import org.apache.lucene.search.QueryCachingPolicy;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.ScoreMode;
import org.apache.lucene.search.Scorer;
import org.apache.lucene.search.TermStatistics;
import org.apache.lucene.search.TopFieldDocs;
import org.apache.lucene.search.TotalHits;
import org.apache.lucene.search.Weight;
import org.apache.lucene.search.similarities.Similarity;
import org.apache.lucene.util.BitSet;
import org.apache.lucene.util.BitSetIterator;
import org.apache.lucene.util.Bits;
import org.apache.lucene.util.CombinedBitSet;
import org.apache.lucene.util.SparseFixedBitSet;
import org.elasticsearch.common.lucene.search.TopDocsAndMaxScore;
import org.elasticsearch.search.DocValueFormat;
import org.elasticsearch.search.dfs.AggregatedDfs;
import org.elasticsearch.search.profile.Timer;
import org.elasticsearch.search.profile.query.ProfileWeight;
import org.elasticsearch.search.profile.query.QueryProfileBreakdown;
import org.elasticsearch.search.profile.query.QueryProfiler;
import org.elasticsearch.search.profile.query.QueryTimingType;
import org.elasticsearch.search.query.QuerySearchResult;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Set;
Expand Down Expand Up @@ -131,12 +139,86 @@ public Weight createWeight(Query query, ScoreMode scoreMode, float boost) throws
}
}

private void checkCancelled() {
if (checkCancelled != null) {
checkCancelled.run();
}
}

public void search(List<LeafReaderContext> leaves, Weight weight, CollectorManager manager,
QuerySearchResult result, DocValueFormat[] formats, TotalHits totalHits) throws IOException {
final List<Collector> collectors = new ArrayList<>(leaves.size());
for (LeafReaderContext ctx : leaves) {
final Collector collector = manager.newCollector();
searchLeaf(ctx, weight, collector);
collectors.add(collector);
}
TopFieldDocs mergedTopDocs = (TopFieldDocs) manager.reduce(collectors);
// Lucene sets shards indexes during merging of topDocs from different collectors
// We need to reset shard index; ES will set shard index later during reduce stage
for (ScoreDoc scoreDoc : mergedTopDocs.scoreDocs) {
scoreDoc.shardIndex = -1;
}
if (totalHits != null) { // we have already precalculated totalHits for the whole index
mergedTopDocs = new TopFieldDocs(totalHits, mergedTopDocs.scoreDocs, mergedTopDocs.fields);
}
result.topDocs(new TopDocsAndMaxScore(mergedTopDocs, Float.NaN), formats);
}

@Override
protected void search(List<LeafReaderContext> leaves, Weight weight, Collector collector) throws IOException {
final Weight cancellableWeight;
if (checkCancelled != null) {
cancellableWeight = new Weight(weight.getQuery()) {
for (LeafReaderContext ctx : leaves) { // search each subreader
searchLeaf(ctx, weight, collector);
}
}

/**
* Lower-level search API.
*
* {@link LeafCollector#collect(int)} is called for every matching document in
* the provided <code>ctx</code>.
*/
private void searchLeaf(LeafReaderContext ctx, Weight weight, Collector collector) throws IOException {
checkCancelled();
weight = wrapWeight(weight);
final LeafCollector leafCollector;
try {
leafCollector = collector.getLeafCollector(ctx);
} catch (CollectionTerminatedException e) {
// there is no doc of interest in this reader context
// continue with the following leaf
return;
}
Bits liveDocs = ctx.reader().getLiveDocs();
BitSet liveDocsBitSet = getSparseBitSetOrNull(liveDocs);
if (liveDocsBitSet == null) {
BulkScorer bulkScorer = weight.bulkScorer(ctx);
if (bulkScorer != null) {
try {
bulkScorer.score(leafCollector, liveDocs);
} catch (CollectionTerminatedException e) {
// collection was terminated prematurely
// continue with the following leaf
}
}
} else {
// if the role query result set is sparse then we should use the SparseFixedBitSet for advancing:
Scorer scorer = weight.scorer(ctx);
if (scorer != null) {
try {
intersectScorerAndBitSet(scorer, liveDocsBitSet, leafCollector,
checkCancelled == null ? () -> { } : checkCancelled);
} catch (CollectionTerminatedException e) {
// collection was terminated prematurely
// continue with the following leaf
}
}
}
}

private Weight wrapWeight(Weight weight) {
if (checkCancelled != null) {
return new Weight(weight.getQuery()) {
@Override
public void extractTerms(Set<Term> terms) {
throw new UnsupportedOperationException();
Expand Down Expand Up @@ -168,48 +250,10 @@ public BulkScorer bulkScorer(LeafReaderContext context) throws IOException {
}
};
} else {
cancellableWeight = weight;
return weight;
}
searchInternal(leaves, cancellableWeight, collector);
}

private void searchInternal(List<LeafReaderContext> leaves, Weight weight, Collector collector) throws IOException {
for (LeafReaderContext ctx : leaves) { // search each subreader
final LeafCollector leafCollector;
try {
leafCollector = collector.getLeafCollector(ctx);
} catch (CollectionTerminatedException e) {
// there is no doc of interest in this reader context
// continue with the following leaf
continue;
}
Bits liveDocs = ctx.reader().getLiveDocs();
BitSet liveDocsBitSet = getSparseBitSetOrNull(liveDocs);
if (liveDocsBitSet == null) {
BulkScorer bulkScorer = weight.bulkScorer(ctx);
if (bulkScorer != null) {
try {
bulkScorer.score(leafCollector, liveDocs);
} catch (CollectionTerminatedException e) {
// collection was terminated prematurely
// continue with the following leaf
}
}
} else {
// if the role query result set is sparse then we should use the SparseFixedBitSet for advancing:
Scorer scorer = weight.scorer(ctx);
if (scorer != null) {
try {
intersectScorerAndBitSet(scorer, liveDocsBitSet, leafCollector,
checkCancelled == null ? () -> {} : checkCancelled);
} catch (CollectionTerminatedException e) {
// collection was terminated prematurely
// continue with the following leaf
}
}
}
}
}

private static BitSet getSparseBitSetOrNull(Bits liveDocs) {
if (liveDocs instanceof SparseFixedBitSet) {
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2 changes: 0 additions & 2 deletions server/src/main/java/org/elasticsearch/search/profile/query/CollectorResult.java
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Original file line number Diff line number Diff line change
Expand Up @@ -49,8 +49,6 @@ public class CollectorResult implements ToXContentObject, Writeable {
public static final String REASON_SEARCH_POST_FILTER = "search_post_filter";
public static final String REASON_SEARCH_MIN_SCORE = "search_min_score";
public static final String REASON_SEARCH_MULTI = "search_multi";
public static final String REASON_SEARCH_TIMEOUT = "search_timeout";
public static final String REASON_SEARCH_CANCELLED = "search_cancelled";
public static final String REASON_AGGREGATION = "aggregation";
public static final String REASON_AGGREGATION_GLOBAL = "aggregation_global";

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53 changes: 0 additions & 53 deletions server/src/main/java/org/elasticsearch/search/query/CancellableCollector.java
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This file was deleted.

15 changes: 0 additions & 15 deletions server/src/main/java/org/elasticsearch/search/query/QueryCollectorContext.java
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Original file line number Diff line number Diff line change
Expand Up @@ -28,16 +28,13 @@
import org.elasticsearch.common.lucene.MinimumScoreCollector;
import org.elasticsearch.common.lucene.search.FilteredCollector;
import org.elasticsearch.search.profile.query.InternalProfileCollector;
import org.elasticsearch.tasks.TaskCancelledException;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.function.BooleanSupplier;

import static org.elasticsearch.search.profile.query.CollectorResult.REASON_SEARCH_CANCELLED;
import static org.elasticsearch.search.profile.query.CollectorResult.REASON_SEARCH_MIN_SCORE;
import static org.elasticsearch.search.profile.query.CollectorResult.REASON_SEARCH_MULTI;
import static org.elasticsearch.search.profile.query.CollectorResult.REASON_SEARCH_POST_FILTER;
Expand Down Expand Up @@ -150,18 +147,6 @@ protected InternalProfileCollector createWithProfiler(InternalProfileCollector i
};
}

/**
* Creates a collector that throws {@link TaskCancelledException} if the search is cancelled
*/
static QueryCollectorContext createCancellableCollectorContext(BooleanSupplier cancelled) {
return new QueryCollectorContext(REASON_SEARCH_CANCELLED) {
@Override
Collector create(Collector in) throws IOException {
return new CancellableCollector(cancelled, in);
}
};
}

/**
* Creates collector limiting the collection to the first <code>numHits</code> documents
*/
Expand Down

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