apache/druid · warning

Asked to remove data segment that doesn't exist!? server

Error message

Asked to remove data segment that doesn't exist!? server[%s], segment[%s]

What it means

In removeDataSegment, when the data source exists but contains no segment matching the given id, dataSource.removeSegment returns null and this warning is logged; currSize/totalSegments are left untouched. Removal is a no-op and the returned removed segment is null.

Solutions

1. Check for duplicate segmentRemove events in coordinator/inventory logs
2. Ensure the segment's add event completed (announced and synced) before its removal
3. Ignore one-off warnings after historical restarts; investigate repeats for the same segment id
4. If size accounting looks wrong, restart the view process to rebuild from a full server inventory sync

if (server.getSegment(segmentId) == null) { log.info("segment absent; skip removal"); return null; }

When it happens

Trigger: removeSegment called with a segment id not present in that DruidServer's data source — duplicate removal, or removal before the add was processed.

Common situations: Race between segment load and drop, duplicated unannounce events, coordinator retrying a drop the view already handled.

Understand the failure class

Background: Record Not Found Errors: "not found", RecordNotFound, and "was not found" — what they mean and how to fix them — this error's family across 28 libraries.

Related errors

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AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/d4db14c454db8760. Report an issue: GitHub.

Appendix: source

Thrown at server/src/main/java/org/apache/druid/client/DruidServer.java:330

        (dataSourceName, dataSource) -> {
          if (dataSource == null) {
            log.warn(
                "Asked to remove data segment from a data source that doesn't exist!? server[%s], segment[%s]",
                getName(),
                segmentId
            );
            // Returning null from the lambda here makes the ConcurrentHashMap to not record any entry.
            return null;
          }
          DataSegment removed = dataSource.removeSegment(segmentId);
          if (removed != null) {
            segmentRemoved[0] = removed;
            // Use effectiveSizeOf (loadedBytes when the value is a DataSegmentAndLoadProfile, else segment size)
            // so the books balance against what we added.
            currSize.addAndGet(-DataSegmentAndLoadProfile.effectiveSizeOf(removed));
            totalSegments.decrementAndGet();
          } else {
            log.warn("Asked to remove data segment that doesn't exist!? server[%s], segment[%s]", getName(), segmentId);
          }
          // Returning null from the lambda here makes the ConcurrentHashMap to remove the current entry.
          return dataSource.isEmpty() ? null : dataSource;
        }
    );
    return segmentRemoved[0];
  }

  public DruidDataSource getDataSource(String dataSource)
  {
    return dataSources.get(dataSource);
  }

  public Collection<DruidDataSource> getDataSources()
  {
    return dataSources.values();
  }

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