databendlabs/databend · error

internal error: entered unreachable code

Error message

internal error: entered unreachable code

What it means

`Xor8Filter::supported_type` checks whether an xor8 bloom (nbf) index supports a column type. For Map types, the inner type is always assumed to be Tuple(k,v); a Map whose inner type is anything else reaches `_ => unreachable!()`, panicking with internal error 1001.

Solutions

1. Fix the column schema so the map inner type is Tuple(String, T), or recreate the table and migrate data
2. Remove the bloom index definition for the malformed map column
3. Report as a bug: supported_type should return false for unexpected inner types rather than panic

Example fix

// before
_ => unreachable!(),
// after
_ => return false,
// or: other => { tracing::warn!("unsupported map inner {:?}", other); false }

-- before declaring an nbf/bloom index on a map column:
DESC <table>;
-- require type to match MAP(TUPLE(String, Supported))

try {
  createIndex(indexDef);
} catch (e) {
  if (e.code === 1001 && /xor8|bloom/.test(e.message)) {
    // remove the index option for that column and recreate
  }
}

When it happens

Trigger: Declaring a bloom index (nbf/bloom filter index) on a MAP column whose inner type metadata is not Tuple — for example Map over a non-tuple type due to schema corruption or an engine-level type change.

Common situations: CREATE TABLE/ALTER with index definitions on maps under a mismatched schema; migrations between Databend versions where map representation changed.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

• internal error: entered unreachable code
• internal error: entered unreachable code
• internal error: entered unreachable code
• invalid map type
• internal error: entered unreachable code

AI-assisted analysis of databendlabs/databend@288d84d76e (2026-09-11). Data as JSON: /api/errors/881d29e8b5b42a7b. Report an issue: GitHub.

Appendix: source

Thrown at src/query/storages/common/index/src/filters/xor8/xor8_filter.rs:176

    }
}

impl Index for Xor8Filter {
    fn supported_type(data_type: &DataType) -> bool {
        let inner_type = data_type.remove_nullable();
        if let DataType::Map(box inner_ty) = inner_type {
            match inner_ty {
                DataType::Tuple(kv_tys) => {
                    return matches!(
                        kv_tys[1].remove_nullable(),
                        DataType::Number(_)
                            | DataType::String
                            | DataType::Variant
                            | DataType::Timestamp
                            | DataType::Date
                    );
                }
                _ => unreachable!(),
            };
        }
        matches!(
            inner_type,
            DataType::Number(_) | DataType::String | DataType::Timestamp | DataType::Date
        )
    }
}

impl Xor8CodecError {
    pub fn new(msg: impl Display, cause: &(impl std::error::Error + 'static)) -> Self {
        Self {
            msg: msg.to_string(),
            cause: AnyError::new(cause),
        }
    }
}

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