Panic when deleting a table that was opened

[Frando]

Hi,
when deleting a table in a transaction where the table was also opened, redb panics with

panicked at 'called `Option::unwrap()` on a `None` value', [...]/redb-1.3.0/src/tree_store/table_tree.rs:527:65

Example:

use redb::{Database, TableDefinition};

const T1: TableDefinition<u64, u64> = TableDefinition::new("t1");

fn main() -> anyhow::Result<()> {
    let db = Database::create("./foo.db")?;
    let tx = db.begin_write()?;
    {
        let _t1 = tx.open_table(T1)?;
        tx.delete_table(T1)?;
    }
    tx.commit()?;
    Ok(())
}

I was quite surprised by this. Can this be made into an error instead of panicking? We'd quite like redb to not panic. And if it is expected behavior, should it be added to the docs that WriteTransaction::delete_table may not be called on tables that are opened in the same transaction.

In iroh we have a database migration that moves values from a table-old into a table-new, and then deletes table-old. It looks roughly like this, and we'd preferably run this in a single transaction for idempotency. Am I missing something or is this not possible?

let tx = db.begin_write()?;
{
    let old_table_exists = tx
        .list_tables()?
        .any(|handle| handle.name() == TABLE_OLD.name());
    if !old_table_exists {
        return Ok(());
    }

    let table_old = tx.open_table(TABLE_OLD)?;
    let mut table_new = tx.open_table(TABLE_NEW)?;
    let iter = table_old.iter()?;
    for row in iter {
        let (k, v) = row?;
        table_new.insert(k.value(), migrate_value(v.value())?;
    }
    tx.delete_table(TABLE_OLD)?;
}
tx.commit()?;

[Frando]

Wow, this was fast! Thank you 🙏

[cberner]

For sure!