prestodb/presto · critical · IllegalArgumentException

Deserialized SingleMapBlock violates invariants: expected…

Error message

Deserialized SingleMapBlock violates invariants: expected hashtable size %d, actual hashtable size %d

What it means

SingleMapBlockEncoding.readBlock validates that the deserialized hash table's length equals keyBlock.getPositionCount() * HASH_MULTIPLIER. The hash table is a fixed-size open-addressing structure sized proportionally to the entry count; any other size means the stream is malformed or from an incompatible producer, so readBlock throws IllegalArgumentException with expected vs actual size.

Solutions

1. Align Presto versions across all cluster nodes to fix HASH_MULTIPLIER/encoding skew.
2. Regenerate corrupted spill or exchange data; check disk and network reliability.
3. If writing the encoding manually, size the hash table as positionCount * HASH_MULTIPLIER.
4. Retry the operation and enable checksums to surface corruption earlier.

Example fix

// before
int[] hashTable = new int[keyBlock.getPositionCount()]; // wrong size
// after
int[] hashTable = new int[keyBlock.getPositionCount() * HASH_MULTIPLIER];

// writer-side pre-check
int expected = keyBlock.getPositionCount() * HASH_MULTIPLIER;
if (hashTables != null && hashTables.length != expected) {
    throw new IllegalStateException("hash table size " + hashTables.length + " != expected " + expected);
}

try {
    Block block = blockEncoding.readBlock(sliceInput);
} catch (IllegalArgumentException e) {
    if (e.getMessage().contains("expected hashtable size")) {
        throw new CorruptedPageException("Map block hashtable size mismatch — version skew or corrupted data", e);
    }
    throw e;
}

When it happens

Trigger: Deserializing a MapBlock where hashTables length != keyBlock.getPositionCount() * HASH_MULTIPLIER — corrupted spill/exchange bytes, wrong HASH_MULTIPLIER version skew between writer and reader, or a custom serializer emitting a wrong-sized hash table.

Common situations: Cluster nodes on different Presto versions exchanging pages, truncated spill files, hand-rolled connectors writing MapBlock encoding manually.

Related errors

• Deserialized SingleMapBlock violates invariants: key
• A null map must have zero entries
• Failed to append record
• GENERIC_INTERNAL_ERROR
• GENERIC_INTERNAL_ERROR

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/c8933fa13a8547bc. Report an issue: GitHub.

Appendix: source

Thrown at presto-common/src/main/java/com/facebook/presto/common/block/SingleMapBlockEncoding.java:79

    public Block readBlock(BlockEncodingSerde blockEncodingSerde, SliceInput sliceInput)
    {
        Block keyBlock = blockEncodingSerde.readBlock(sliceInput);
        Block valueBlock = blockEncodingSerde.readBlock(sliceInput);

        int hashTableLength = sliceInput.readInt();
        int[] hashTable = null;
        if (hashTableLength >= 0) {
            hashTable = new int[hashTableLength];
            sliceInput.readBytes(wrappedIntArray(hashTable));
        }

        if (keyBlock.getPositionCount() != valueBlock.getPositionCount()) {
            throw new IllegalArgumentException(
                    format("Deserialized SingleMapBlock violates invariants: key %d, value %d", keyBlock.getPositionCount(), valueBlock.getPositionCount()));
        }

        if (hashTable != null && keyBlock.getPositionCount() * HASH_MULTIPLIER != hashTable.length) {
            throw new IllegalArgumentException(
                    format("Deserialized SingleMapBlock violates invariants: expected hashtable size %d, actual hashtable size %d", keyBlock.getPositionCount() * HASH_MULTIPLIER, hashTable.length));
        }

        MapBlock mapBlock = MapBlock.createMapBlockInternal(
                0,
                1,
                Optional.empty(),
                new int[] {0, keyBlock.getPositionCount()},
                keyBlock,
                valueBlock,
                new HashTables(Optional.ofNullable(hashTable), 1));

        return new SingleMapBlock(0, 0, keyBlock.getPositionCount() * 2, mapBlock);
    }
}

View on GitHub (pinned to 55bb57d202)