What causes "NotRegexMatch function not registered" in influxdata/influxdb?

Run the full UDF registration (all query_functions UDFs) on your context before building expressions.

NotRegexMatch function not registered

Error message

NotRegexMatch function not registered

What it means

`regex_not_match_expr` mirrors `regex_match_expr` for the `!~` operator and panics when the NotRegexMatch UDF is absent from the registry. The `.expect()` encodes the assumption that UDF registration happened at context construction. Seeing this panic means the registry was built without the negated regex-match UDF.

Solutions

Run the full UDF registration (all query_functions UDFs) on your context before building expressions.
Verify NotRegexMatch appears in the registry's UDF list.
Update registration code if the UDF name constant changed after an upgrade.

Example fix

// before
register_udf(REGEX_MATCH_UDF_NAME); // partial registration
// after
register_udf(REGEX_MATCH_UDF_NAME);
register_udf(REGEX_NOT_MATCH_UDF_NAME); // both variants

Defensive patterns

Strategy: type-guard

Validate before calling

debug_assert!(registry().udf(regex::REGEX_NOT_MATCH_UDF_NAME).is_some(), "NotRegexMatch UDF not registered");

Type guard

fn has_regex_not_match_udf(registry: &SessionContext) -> bool {
    registry.udf(regex::REGEX_NOT_MATCH_UDF_NAME).is_some()
}

Try / catch

let udf = registry().udf(regex::REGEX_NOT_MATCH_UDF_NAME)
    .ok_or_else(|| anyhow!("NotRegexMatch UDF not registered"))?;

Prevention

Register RegexMatch and NotRegexMatch together in one registration function
Never build exprs on a bare context; go through the crate's registry
Enumerate all UDF name constants in a registration completeness test

When it happens

Trigger: Calling `regex_not_match_expr(input, pattern)` when `registry().udf(regex::REGEX_NOT_MATCH_UDF_NAME)` returns None — NotRegexMatch was never registered on the context.

Common situations: Manually constructed SessionContext without the crate's UDF registration; test helpers that registered RegexMatch but not NotRegexMatch; version drift renaming the UDF.

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

AI-assisted analysis of influxdata/influxdb@06200ef96b (2026-09-19). Data as JSON: /api/errors/823332783d53c5c8. Report an issue: GitHub.

Appendix: source

Thrown at core/query_functions/src/lib.rs:83

/// col ~= /pattern/
/// ```
pub fn regex_match_expr(input: Expr, pattern: String) -> Expr {
    registry()
        .udf(regex::REGEX_MATCH_UDF_NAME)
        .expect("RegexMatch function not registered")
        .call(vec![input, lit(pattern)])
}

/// Return an Expr that invokes a InfluxRPC compatible regex match to
/// determine which values do not satisfy the pattern. Equivalent to:
///
/// ```text
/// col !~ /pattern/
/// ```
pub fn regex_not_match_expr(input: Expr, pattern: String) -> Expr {
    registry()
        .udf(regex::REGEX_NOT_MATCH_UDF_NAME)
        .expect("NotRegexMatch function not registered")
        .call(vec![input, lit(pattern)])
}

/// Create a DataFusion `Expr` that invokes `window_bounds` with the
/// appropriate every and offset arguments at runtime
pub fn make_window_bound_expr(
    time_arg: Expr,
    every: WindowDuration,
    offset: WindowDuration,
) -> Expr {
    let encoded_every: EncodedWindowDuration = every.into();
    let encoded_offset: EncodedWindowDuration = offset.into();

    registry()
        .udf(window::WINDOW_BOUNDS_UDF_NAME)
        .expect("WindowBounds function not registered")
        .call(vec![
            time_arg,

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