clintropolis commented on a change in pull request #8495: Check
targetCompactionSizeBytes to search for candidate segments in auto compaction
URL: https://github.com/apache/incubator-druid/pull/8495#discussion_r322510975
##########
File path:
server/src/main/java/org/apache/druid/server/coordinator/helper/SegmentCompactorUtil.java
##########
@@ -20,21 +20,36 @@
package org.apache.druid.server.coordinator.helper;
import com.google.common.base.Preconditions;
+import org.apache.druid.timeline.DataSegment;
import org.joda.time.Interval;
+import javax.annotation.Nullable;
+import java.util.List;
+
/**
* Util class used by {@link DruidCoordinatorSegmentCompactor} and {@link
CompactionSegmentSearchPolicy}.
*/
class SegmentCompactorUtil
{
- static boolean isCompactibleSize(long targetBytes, long currentTotalBytes,
long additionalBytes)
- {
- return currentTotalBytes + additionalBytes <= targetBytes;
- }
+ /**
+ * The allowed error rate of the segment size after compaction.
+ * Its value is determined experimentally.
+ */
+ private static final double ALLOWED_ERROR_OF_SEGMENT_SIZE = .2;
- static boolean isCompactibleNum(int numTargetSegments, int
numCurrentSegments, int numAdditionalSegments)
+ static boolean needsCompaction(@Nullable Long targetCompactionSizeBytes,
List<DataSegment> candidates)
{
- return numCurrentSegments + numAdditionalSegments <= numTargetSegments;
+ if (targetCompactionSizeBytes == null) {
+ // If targetCompactionSizeBytes is null, we have no way to check that
the given segments need compaction or not.
+ return true;
+ }
+ final double minAllowedSize = targetCompactionSizeBytes * (1 -
ALLOWED_ERROR_OF_SEGMENT_SIZE);
+ final double maxAllowedSize = targetCompactionSizeBytes * (1 +
ALLOWED_ERROR_OF_SEGMENT_SIZE);
+
+ return candidates
+ .stream()
+ .filter(segment -> segment.getSize() < minAllowedSize ||
segment.getSize() > maxAllowedSize)
+ .count() > 1;
Review comment:
~nit: I think this should use `anyMatch` instead of `filter` + `count` since
the former might not have to materialize the entire set upon reaching first
match~
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