prestodb/presto · error · PrestoException

NOT_SUPPORTED

NOT_SUPPORTED

Error message

Can't convert json to MongoDB Document: %s

What it means

MongoDB sink conversion error in getObjectValue: a Presto value of some type could not be converted into a MongoDB Document/BSON value (unsupported or mismatched type encountered while writing a row). The %s describes the offending JSON/type; this fires during INSERT into a MongoDB table.

Source

Thrown at presto-mongodb/src/main/java/com/facebook/presto/mongodb/MongoPageSink.java:187

            // TODO: decimal type might not support yet
            // TODO: this code is likely wrong and should switch to Decimals.readBigDecimal()
            DecimalType decimalType = (DecimalType) type;
            BigInteger unscaledValue;
            if (decimalType.isShort()) {
                unscaledValue = BigInteger.valueOf(decimalType.getLong(block, position));
            }
            else {
                unscaledValue = Decimals.decodeUnscaledValue(decimalType.getSlice(block, position));
            }
            return new BigDecimal(unscaledValue);
        }
        if (isJsonType(type)) {
            String json = type.getSlice(block, position).toStringUtf8();
            try {
                return parse(json);
            }
            catch (BsonInvalidOperationException e) {
                throw new PrestoException(NOT_SUPPORTED, "Can't convert json to MongoDB Document: " + json, e);
            }
        }
        if (isArrayType(type)) {
            Type elementType = type.getTypeParameters().get(0);

            Block arrayBlock = block.getBlock(position);

            List<Object> list = new ArrayList<>(arrayBlock.getPositionCount());
            for (int i = 0; i < arrayBlock.getPositionCount(); i++) {
                Object element = getObjectValue(elementType, arrayBlock, i);
                list.add(element);
            }

            return unmodifiableList(list);
        }
        if (isMapType(type)) {
            Type keyType = type.getTypeParameters().get(0);
            Type valueType = type.getTypeParameters().get(1);

View on GitHub (pinned to 55bb57d202)

Solutions

1. Cast the problematic column to a BSON-supported type (string, double, etc.) before insert
2. Avoid writing types the MongoDB connector does not support (e.g. some decimals/time zones)
3. Restructure nested types into simpler BSON-compatible shapes

When it happens

Trigger: Thrown at presto-mongodb/src/main/java/com/facebook/presto/mongodb/MongoPageSink.java:187 when the library encounters an invalid state.

Common situations: See trigger scenarios.

Understand the failure class

Background: Presto NOT_SUPPORTED error: what "not supported" means and how to fix it — this error's family across 3 libraries.

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/51c84d80befdc62d. Report an issue: GitHub.