prestodb/presto · error · PrestoException

INVALID_FUNCTION_ARGUMENT

INVALID_FUNCTION_ARGUMENT

Error message

Entropy count argument must be non-negative

What it means

INVALID_FUNCTION_ARGUMENT thrown by the entropy aggregation's input function when the count argument is negative. entropy() treats its BIGINT argument as a count of observations feeding the running entropy computation; a negative count is meaningless and invalid. Zero counts are allowed and short-circuit to a no-op.

Source

Thrown at presto-main-base/src/main/java/com/facebook/presto/operator/aggregation/EntropyAggregation.java:54

 */
@AggregationFunction("entropy")
@Description("Takes non-negative count inputs, and computes the log-2 entropy of their fractions when normalized to sum to 1.")
public final class EntropyAggregation
{
    private EntropyAggregation() {}

    /**
     * @note If count is negative, the value of the aggregation will be null; if
     * count is 0, this is a no-op (since, in the context of entropy, 0 log(0) = 0; if count is null,
     * this is a no op.
     */
    @InputFunction
    public static void input(
            @AggregationState EntropyState state,
            @SqlType(StandardTypes.BIGINT) long count)
    {
        if (count < 0) {
            throw new PrestoException(
                    INVALID_FUNCTION_ARGUMENT,
                    "Entropy count argument must be non-negative");
        }

        if (count == 0) {
            return;
        }
        state.setSumC(state.getSumC() + count);
        state.setSumCLogC(state.getSumCLogC() + count * Math.log(count));
    }

    @CombineFunction
    public static void combine(@AggregationState EntropyState state, @AggregationState EntropyState otherState)
    {
        state.setSumC(state.getSumC() + otherState.getSumC());
        state.setSumCLogC(state.getSumCLogC() + otherState.getSumCLogC());
    }

View on GitHub (pinned to 55bb57d202)

Solutions

1. Filter out negative counts: SELECT entropy(cnt) FROM t WHERE cnt >= 0.
2. Clamp with GREATEST(cnt, 0) if negative values should be treated as zero.
3. Fix the upstream expression so counts are guaranteed non-negative.
4. Use TRY(entropy(...)) only if you want the whole aggregation to degrade to NULL rather than fail.

Example fix

// before
SELECT entropy(cnt) FROM events;
// after
SELECT entropy(GREATEST(cnt, 0)) FROM events; -- or WHERE cnt >= 0

-- ensure count is non-negative before aggregating:
SELECT entropy(GREATEST(cnt, 0)) FROM t; -- or: WHERE cnt >= 0

try {
    rs = stmt.executeQuery("SELECT entropy(cnt) FROM t");
} catch (SQLException e) {
    if (e.getMessage() != null && e.getMessage().contains("Entropy count argument must be non-negative")) {
        throw new IllegalArgumentException("entropy() requires cnt >= 0", e);
    }
    throw e;
}

When it happens

Trigger: Calling entropy(count) where count is a BIGINT value < 0 — from a negative literal, a column holding negative values, or an expression (e.g. a difference or delta) that yields a negative number on some rows.

Common situations: Computing entropy over delta/derived columns that can go negative; dirty data with negative counts; sign errors in expressions feeding the aggregate.

Related errors

• INVALID_FUNCTION_ARGUMENT
• INVALID_FUNCTION_ARGUMENT
• INVALID_FUNCTION_ARGUMENT
• INVALID_FUNCTION_ARGUMENT
• INVALID_FUNCTION_ARGUMENT

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/76ea69028e5e35cf. Report an issue: GitHub.