carlosdelest commented on code in PR #13430:
URL: https://github.com/apache/lucene/pull/13430#discussion_r1626064947
##########
lucene/core/src/java/org/apache/lucene/index/TieredMergePolicy.java:
##########
@@ -522,21 +550,28 @@ private MergeSpecification doFindMerges(
final List<SegmentCommitInfo> candidate = new ArrayList<>();
boolean hitTooLarge = false;
long bytesThisMerge = 0;
+ long docCountThisMerge = 0;
for (int idx = startIdx;
idx < sortedEligible.size()
&& candidate.size() < mergeFactor
- && bytesThisMerge < maxMergedSegmentBytes;
+ && bytesThisMerge < maxMergedSegmentBytes
+ && docCountThisMerge < allowedDocCount;
idx++) {
final SegmentSizeAndDocs segSizeDocs = sortedEligible.get(idx);
final long segBytes = segSizeDocs.sizeInBytes;
-
+ int segDocCount = segSizeDocs.maxDoc - segSizeDocs.delCount;
+ if (docCountThisMerge + segDocCount > allowedDocCount) {
+ // We don't want to merge segments that will produce more
documents than allowedDocCount
+ continue;
Review Comment:
Makes sense, thanks!
##########
lucene/core/src/test/org/apache/lucene/index/TestTieredMergePolicy.java:
##########
@@ -77,20 +77,23 @@ protected void assertSegmentInfos(MergePolicy policy,
SegmentInfos infos) throws
long levelSizeBytes = Math.max(minSegmentBytes, (long)
(tmp.getFloorSegmentMB() * 1024 * 1024));
long bytesLeft = totalBytes;
double allowedSegCount = 0;
+ final int maxNumSegmentsOnHighestTier =
+ (int) Math.max(tmp.getSegmentsPerTier(),
tmp.getTargetSearchConcurrency());
// below we make the assumption that segments that reached the max segment
// size divided by 2 don't need merging anymore
int mergeFactor = (int) Math.min(tmp.getSegmentsPerTier(),
tmp.getMaxMergeAtOnce());
while (true) {
final double segCountLevel = bytesLeft / (double) levelSizeBytes;
- if (segCountLevel < tmp.getSegmentsPerTier() || levelSizeBytes >=
maxMergedSegmentBytes / 2) {
+ if (segCountLevel < maxNumSegmentsOnHighestTier
Review Comment:
Good catch - updating
##########
lucene/core/src/java/org/apache/lucene/index/TieredMergePolicy.java:
##########
@@ -522,21 +550,28 @@ private MergeSpecification doFindMerges(
final List<SegmentCommitInfo> candidate = new ArrayList<>();
Review Comment:
> Merging is only necessary if there are more segments than necessary or
more deletes than necessary.
The problem is that sortedEligible has filtered out the segments that cannot
be merged (like those that are bigger than max segment size), so this condition
will skip trying to merge even if we have more segments than allowed.
So for example we may have 17 segments total, from which we can just have 12
sortedEligibles, and have 15 allowed segment count. We would never try to merge
the eligible segments as they're less than the number of allowed segment counts.
Should we take into account the total number of segments vs the total
eligibles for this condition?
##########
lucene/core/src/test/org/apache/lucene/index/TestTieredMergePolicy.java:
##########
@@ -111,11 +114,29 @@ protected void assertSegmentInfos(MergePolicy policy,
SegmentInfos infos) throws
}
}
+ // There can be more segments if we can't merge docs - they are balanced
between segments
+ int maxDocsPerSegment = tmp.getMaxAllowedDocs(infos.totalMaxDoc());
Review Comment:
Yes, we should. Thanks!
##########
lucene/core/src/test/org/apache/lucene/index/TestTieredMergePolicy.java:
##########
@@ -111,11 +114,29 @@ protected void assertSegmentInfos(MergePolicy policy,
SegmentInfos infos) throws
}
}
+ // There can be more segments if we can't merge docs - they are balanced
between segments
+ int maxDocsPerSegment = tmp.getMaxAllowedDocs(infos.totalMaxDoc());
+ List<Integer> segmentDocs =
+ infos.asList().stream()
+ .map(info -> info.info.maxDoc() - info.getDelCount())
+ .sorted()
+ .toList();
+ int numEligible = 0;
+ int currentSum = 0;
+ for (int i = 0; i < segmentDocs.size(); i++) {
+ currentSum += segmentDocs.get(i);
+ if (currentSum > maxDocsPerSegment) {
+ break;
+ }
+ numEligible++;
+ }
+ boolean eligibleDocsMerge = numEligible > 1;
Review Comment:
Correct, applied the change.
##########
lucene/core/src/java/org/apache/lucene/index/TieredMergePolicy.java:
##########
@@ -916,14 +951,13 @@ public MergeSpecification
findForcedDeletesMerges(SegmentInfos infos, MergeConte
final Set<SegmentCommitInfo> merging = mergeContext.getMergingSegments();
boolean haveWork = false;
+ int totalDelCount = 0;
for (SegmentCommitInfo info : infos) {
int delCount = mergeContext.numDeletesToMerge(info);
assert assertDelCount(delCount, info);
+ totalDelCount += delCount;
double pctDeletes = 100. * ((double) delCount) / info.info.maxDoc();
- if (pctDeletes > forceMergeDeletesPctAllowed && !merging.contains(info))
{
- haveWork = true;
- break;
- }
+ haveWork = haveWork || (pctDeletes > forceMergeDeletesPctAllowed &&
!merging.contains(info));
Review Comment:
The idea is to use the loop to count all delete counts, and use it for
calculating the max number of allowed docs down below. Is there any other way
of retrieving the number of deleted docs without looping over all
`SegmentCommitInfo`s?
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