databendlabs/databend · error

Temp table id used up

Error message

Temp table id used up

What it means

The session-local temp-table manager allocates temp table IDs by incrementing a counter; each ID must stay within the reserved temp-table ID range checked by `is_temp_table_id`. When the counter is incremented past the last valid temp ID, it panics with 'Temp table id used up', because continuing would collide with ordinary (persistent) table IDs.

Solutions

1. Restart the session or reconnect — the temp ID counter is per-session, so a new session resets it.
2. Audit the code path for temp-table creation loops that never drop tables, and reuse/drop temp tables instead of always creating new ones.
3. Refactor to recycle freed temp IDs (maintain a free list) instead of a monotonically increasing counter.

// Before creating another temp table in a long session, check the counter headroom
if !is_temp_table_id(next_id.wrapping_add(1)) {
    // close and reopen the session to reset the per-session counter
}

// The panic aborts the session task; wrap the batch temp-table workload
match result {
    Err(err) if err.message() == "Temp table id used up" => {
        recreate_session_and_retry();
    }
    other => other?,
}

When it happens

Trigger: Calling `create_table` for temporary tables so many times within one session that `next_id` exceeds the highest value satisfying `is_temp_table_id` (u64 range: temp IDs occupy the high range near u64::MAX, requiring ~2^63+ creations).

Common situations: Extremely long-lived sessions creating/destroying temp tables at very high volume; practically only seen in stress tests or leaks where temp tables are created in a loop for weeks without session restart.

Understand the failure class

Background: "value must be between 0 and 1" / "out of range" / "must not be negative" errors: fixing range-validation failures across open-source libraries — this error's family across 42 libraries.

Related errors

• Invalid temp table desc
• login_handler expect session id in ctx
• mysql handler should be authed when call
• {}
• expect tuple type

AI-assisted analysis of databendlabs/databend@288d84d76e (2026-09-11). Data as JSON: /api/errors/d97b0752cd59208b. Report an issue: GitHub.

Appendix: source

Thrown at src/query/storages/common/session/src/temp_table.rs:101

    pub db_name: String,
    pub table_name: String,
    pub meta: TableMeta,
    pub copied_files: BTreeMap<String, TableCopiedFileInfo>,
}

impl TempTblMgr {
    fn temp_table_desc(db_name: &str, table_name: &str) -> String {
        format!("'{}'.'{}'", db_name, table_name)
    }

    pub fn init() -> Arc<Mutex<Self>> {
        Arc::new(Mutex::new(Self::default()))
    }

    fn inc_next_id(&mut self) {
        self.next_id += 1;
        if !is_temp_table_id(self.next_id) {
            panic!("Temp table id used up");
        }
    }

    pub fn is_empty(&self) -> bool {
        self.id_to_table.is_empty() && self.staged_tables.is_empty()
    }

    pub fn create_table(
        &mut self,
        req: CreateTableReq,
        prefix: String,
    ) -> Result<CreateTableReply> {
        let CreateTableReq {
            create_option,
            name_ident,
            table_meta,
            as_dropped,
            ..

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