apache/cassandra · error · IllegalArgumentException

The length of the provided dictionary array (<dict.length>)…

Error message

The length of the provided dictionary array (<dict.length>) is not equal to provided length value (<dictLength>).

What it means

validate() cross-checks that the declared dictLength equals dict.length. A mismatch means the descriptor's metadata disagrees with the actual payload, which would corrupt the import checksum and storage, so it is rejected with both lengths in the message.

Solutions

1. Pass dict.length as dictLength so both match the actual payload
2. Re-read the dictionary file completely and regenerate the descriptor from the same buffer
3. If metadata says otherwise, investigate why the file is truncated or corrupted instead of forcing the length

Example fix

// before
new CompressionDictionaryDataObject(..., dict, headerDeclaredLength, ...);
// after
new CompressionDictionaryDataObject(..., dict, dict.length, ...);

if (obj.dict == null || obj.dictLength != obj.dict.length) throw new IllegalArgumentException("dictLength (" + obj.dictLength + ") must equal dict.length (" + (obj.dict == null ? -1 : obj.dict.length) + ")");

boolean lengthsConsistent(CompressionDictionaryDataObject o) { return o.dict != null && o.dictLength == o.dict.length; }

try { tabularData.fromDataObject(obj); } catch (IllegalArgumentException e) { if (e.getMessage().contains("not equal to provided length value")) { /* rebuild with dictLength = dict.length */ } else throw e; }

When it happens

Trigger: Constructing CompressionDictionaryDataObject where dictLength != dict.length — e.g. the length came from stale metadata while the byte array was re-read/truncated, or the caller passed a partial buffer with the original length.

Common situations: Truncated dictionary files whose header still declares the original size; off-by-one or unit errors (chars vs bytes) when computing length; mixing descriptors and payloads from different dictionary versions.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• Keyspace not specified.
• Provided dictionary byte array is null or empty.
• Provided dictionary id must be positive but it is
• Provided kind is null.
• Size has to be strictly positive number, it is

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/27c2d8a29819c552. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/db/compression/CompressionDictionaryDetailsTabularData.java:314

                throw new IllegalArgumentException("Provided dictionary byte array is null or empty.");
            if (kind == null)
                throw new IllegalArgumentException("Provided kind is null.");

            CompressionDictionary.Kind dictionaryKind;

            try
            {
                dictionaryKind = CompressionDictionary.Kind.valueOf(kind);
            }
            catch (IllegalArgumentException ex)
            {
                throw new IllegalArgumentException("There is no such dictionary kind like '" + kind + "'. Available kinds: " + Arrays.asList(CompressionDictionary.Kind.values()));
            }

            if (dictLength <= 0)
                throw new IllegalArgumentException("Size has to be strictly positive number, it is '" + dictLength + "'.");
            if (dict.length != dictLength)
                throw new IllegalArgumentException("The length of the provided dictionary array (" + dict.length + ") is not equal to provided length value (" + dictLength + ").");
            if (createdAt == null)
                throw new IllegalArgumentException("The creation date not specified.");

            int checksumOfDictionaryToImport = CompressionDictionary.calculateChecksum((byte) dictionaryKind.ordinal(), dictId, dict);
            if (checksumOfDictionaryToImport != dictChecksum)
            {
                throw new IllegalArgumentException(format("Computed checksum of dictionary to import (%s) is different from checksum specified on input (%s).",
                                                          checksumOfDictionaryToImport,
                                                          dictChecksum));
            }
        }
    }
}

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