quarkusio/quarkus · error · PanacheQueryException

There should be no more than one result

Error message

There should be no more than one result

What it means

Thrown by MongoDB Panache's singleResultOptional() when the query fetches two results and finds more than one. The method loads at most 2 documents to distinguish zero, one and many matches; size > 1 means the query is not uniquely selective (e.g., a find on a non-unique field), so returning an Optional would silently hide the ambiguity and the guard aborts instead. Contrast with singleResult(), which also rejects the zero-match case.

Source

Thrown at extensions/panache/mongodb-panache-common/runtime/src/main/java/io/quarkus/mongodb/panache/common/runtime/CommonPanacheQueryImpl.java:234

    }

    public <T extends Entity> Optional<T> firstResultOptional() {
        return Optional.ofNullable(firstResult());
    }

    public <T extends Entity> T singleResult() {
        List<T> list = list(2);
        if (list.size() != 1) {
            throw new PanacheQueryException("There should be only one result");
        }

        return list.get(0);
    }

    public <T extends Entity> Optional<T> singleResultOptional() {
        List<T> list = list(2);
        if (list.size() > 1) {
            throw new PanacheQueryException("There should be no more than one result");
        }

        return list.isEmpty() ? Optional.empty() : Optional.of(list.get(0));
    }

    private void manageOffsets(FindIterable find, Integer limit) {
        if (range != null) {
            find.skip(range.getStartIndex());
            if (limit == null) {
                // range is 0 based, so we add 1 to the limit
                find.limit(range.getLastIndex() - range.getStartIndex() + 1);
            }
        } else if (page != null) {
            find.skip(page.index * page.size);
            if (limit == null) {
                find.limit(page.size);
            }
        }

View on GitHub (pinned to e1c734241f)

Solutions

1. Refine the query filter so it can match at most one document (query by unique _id or a unique field).
2. Deduplicate the collection data.
3. If multiple rows are legitimate, use firstResult() or list() instead.

Example fix

// before
Optional<User> u = PanacheQuery.find("lastName", name).singleResultOptional(); // throws if 2+ users share the name
// after
Optional<User> u = PanacheQuery.find("email", email).singleResultOptional(); // query by unique field

long count = PanacheEntity.count("email", email);
if (count > 1) { /* handle duplicates first */ }

try {
    Optional<MyEntity> e = query.singleResultOptional();
} catch (PanacheQueryException e) {
    // more than one row; use list() and disambiguate
}

When it happens

Trigger: Calling query.singleResultOptional() on a query that matches two or more documents.

Common situations: Query by non-unique field (e.g. email not indexed as unique); MongoDB data mutated concurrently between design and runtime; missing filter matching all documents.

Related errors

• There should be only one result
• Cannot call a page related method in a ranged query, call pa
• There should be only one result
• There should be no more than one result
• Illegal read preference configured in the @MongoEntity anno

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/36fe12c5c2f432a3. Report an issue: GitHub.