databendlabs/databend · error

column view storage type mismatch

Error message

column view storage type mismatch

What it means

push_typed downcasts the column storage's underlying Any data to Vec<ColumnView<T>> for the compile-time type T of the pushed entry. The expect panics when the storage holds views of a different type than the handler's T — the storage type and the entry type disagree, an internal type-tag invariant violation.

Solutions

1. Verify the entry's data type matches the storage's declared data_type before pushing.
2. Ensure handler_for and storage construction use the same (fully unwrapped, non-nullable-normalized) DataType.
3. Check for schema mismatch upstream: a query or insert supplying values of the wrong type should be rejected earlier.
4. File a bug with the query/types involved; this is an internal invariant violation.

if entry.data_type() != &storage.data_type {
    return Err(ErrorCode::Internal("pushed entry type does not match column storage type"));
}

fn matches_storage<T: AccessType>(storage: &ColumnStorage, entry: &BlockEntry) -> bool {
    entry.data_type() == &storage.data_type && storage.data.downcast_ref::<Vec<ColumnView<T>>>().is_some()
}

When it happens

Trigger: Calling push_typed (via BlockVec push paths) with an entry whose AccessType T does not match the type the ColumnStorage was created with — e.g. handler lookup used one DataType while the storage was initialized with another.

Common situations: Bugs in type-handler dispatch (handler_for returning the wrong specialization), schema/type changes not propagated to existing column storage, or expressions producing values of a different type than the declared column type.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

• column view type mismatch
• internal error: entered unreachable code
• {}
• Temp table id used up
• Invalid temp table desc

AI-assisted analysis of databendlabs/databend@288d84d76e (2026-09-11). Data as JSON: /api/errors/98eb116273f9b967. Report an issue: GitHub.

Appendix: source

Thrown at src/query/expression/src/block_vec.rs:438

        DataBlock::new(entries, 0)
    }

    fn init_typed<T: AccessType>(entry: BlockEntry, size_hit: usize) -> Result<ColumnStorage> {
        let data_type = entry.data_type();
        let mut data = Box::new(Vec::<ColumnView<T>>::with_capacity(size_hit));
        data.push(entry.downcast::<T>()?);
        Ok(ColumnStorage {
            data_type,
            data: data as _,
        })
    }

    fn push_typed<T: AccessType>(storage: &mut ColumnStorage, entry: BlockEntry) -> Result<()> {
        let views = storage
            .data
            .downcast_mut::<Vec<ColumnView<T>>>()
            .expect("column view storage type mismatch");
        views.push(entry.downcast::<T>()?);
        Ok(())
    }

    fn replace_typed<T: AccessType>(storage: &mut ColumnStorage, index: usize, entry: BlockEntry) {
        let views = storage
            .data
            .downcast_mut::<Vec<ColumnView<T>>>()
            .expect("column view storage type mismatch");
        let view = entry.downcast::<T>().expect("column view type mismatch");
        views[index] = view;
    }

    fn handler_for(data_type: &DataType) -> TypeHandler {
        match data_type {
            DataType::Nullable(inner) => Self::handler_for_nullable(inner),
            _ => Self::handler_for_non_nullable(data_type),
        }

View on GitHub (pinned to 288d84d76e)