apache/cassandra · warning

Deserialized partition cell count histogram with

Error message

Deserialized partition cell count histogram with {} values greater than the maximum of {}. Clearing the overflow bucket to allow for degraded mean and percentile calculations...

What it means

Same overflow handling as the partition-size histogram, but for the per-partition cell-count histogram in StatsMetadata. Deserialization finds cell counts above the histogram's largest bucket, logs a warning, and clears the overflow bucket so statistics remain computable though degraded.

Solutions

1. Inspect for wide partitions using `nodetool toppartitions` and adjust the data model or bucketing
2. Compact the affected sstables to regenerate histograms
3. Accept degraded stats if data correctness is confirmed
4. Rebuild the table from other replicas if corruption is suspected

Example fix

null

EstimatedHistogram cellCounts = StatsMetadata.serializer.deserialize(version, in);
if (cellCounts.isOverflowed()) {
    logger.warn("Cell count histogram overflowed: {} values beyond max {}", cellCounts.overflowCount(), cellCounts.getLargestBucketOffset());
    cellCounts.clearOverflow();
}

boolean isHistogramUsable(EstimatedHistogram h) { return h != null && !h.isOverflowed(); }

try { StatsMetadata sm = StatsMetadata.serializer.deserialize(version, in); } catch (IOException e) { /* treat sstable metadata as corrupt, trigger repair */ }

When it happens

Trigger: Reading -Statistics.db metadata where partition cell counts exceeded the EstimatedHistogram's maximum bucket when written (tables with very wide rows).

Common situations: Tables with extremely wide partitions (millions of cells per partition); schema migrations or compaction history from clusters with different workloads.

Understand the failure class

Background: "value must be between 0 and 1" / "out of range" / "must not be negative" errors: fixing range-validation failures across open-source libraries — this error's family across 42 libraries.

Related errors

• Deserialized partition size histogram with
• Corrupt flags value for clustering prefix (isStatic flag…
• Invalid large Columns subset: missing index
• Invalid large Columns subset: present index
• Cannot deserialize index summary from

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/7765fc8c54faf156. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/io/sstable/metadata/StatsMetadata.java:541

        public StatsMetadata deserialize(Version version, DataInputPlus in) throws IOException
        {
            EstimatedHistogram partitionSizes = EstimatedHistogram.serializer.deserialize(in);

            if (partitionSizes.isOverflowed())
            {
                logger.warn("Deserialized partition size histogram with {} values greater than the maximum of {}. " +
                            "Clearing the overflow bucket to allow for degraded mean and percentile calculations...",
                            partitionSizes.overflowCount(), partitionSizes.getLargestBucketOffset());

                partitionSizes.clearOverflow();
            }

            EstimatedHistogram columnCounts = EstimatedHistogram.serializer.deserialize(in);

            if (columnCounts.isOverflowed())
            {
                logger.warn("Deserialized partition cell count histogram with {} values greater than the maximum of {}. " +
                            "Clearing the overflow bucket to allow for degraded mean and percentile calculations...",
                            columnCounts.overflowCount(), columnCounts.getLargestBucketOffset());

                columnCounts.clearOverflow();
            }

            CommitLogPosition commitLogLowerBound = CommitLogPosition.NONE, commitLogUpperBound;
            commitLogUpperBound = CommitLogPosition.serializer.deserialize(in);
            long minTimestamp = in.readLong();
            long maxTimestamp = in.readLong();
            long minLocalDeletionTime;
            long maxLocalDeletionTime;
            if (version.hasUIntDeletionTime())
            {
                minLocalDeletionTime = Cell.deletionTimeUnsignedIntegerToLong(in.readInt());
                maxLocalDeletionTime = Cell.deletionTimeUnsignedIntegerToLong(in.readInt());
            }
            else

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