prestodb/presto · error · IllegalStateException

Ambiguous configuration for %s. Matches %s and %s

Error message

Ambiguous configuration for %s. Matches %s and %s

What it means

Thrown by getMatchingSpec when resolving the resource group tree for a query: at the last path segment, two sibling ResourceGroupSpecs expand templates to the same name, so more than one leaf group matches. The manager refuses to pick arbitrarily and fails fast with the two conflicting group names.

Source

Thrown at presto-resource-group-managers/src/main/java/com/facebook/presto/resourceGroups/AbstractResourceConfigurationManager.java:172

            }
        });
    }

    protected Map.Entry<ResourceGroupIdTemplate, ResourceGroupSpec> getMatchingSpec(ResourceGroup group, SelectionContext<VariableMap> context)
    {
        List<ResourceGroupSpec> candidates = getRootGroups();
        List<String> segments = group.getId().getSegments();
        ResourceGroupSpec match = null;
        List<ResourceGroupNameTemplate> templateId = new ArrayList<>();
        for (int i = 0; i < segments.size(); i++) {
            List<ResourceGroupSpec> nextCandidates = null;
            ResourceGroupSpec nextCandidatesParent = null;
            for (ResourceGroupSpec candidate : candidates) {
                if (candidate.getName().expandTemplate(context.getContext()).equals(segments.get(i))) {
                    templateId.add(candidate.getName());
                    if (i == segments.size() - 1) {
                        if (match != null) {
                            throw new IllegalStateException(format("Ambiguous configuration for %s. Matches %s and %s", group.getId(), match.getName(), candidate.getName()));
                        }
                        match = candidate;
                    }
                    else {
                        if (nextCandidatesParent != null) {
                            throw new IllegalStateException(format("Ambiguous configuration for %s. Matches %s and %s", group.getId(), nextCandidatesParent.getName(), candidate.getName()));
                        }
                        nextCandidates = candidate.getSubGroups();
                        nextCandidatesParent = candidate;
                    }
                }
            }
            if (nextCandidates == null) {
                break;
            }
            candidates = nextCandidates;
        }
        checkState(match != null, "No matching configuration found for: %s", group.getId());

View on GitHub (pinned to 55bb57d202)

Solutions

  1. Rename or re-template one of the two conflicting groups reported in the message so only one expands to the same name
  2. Make template patterns mutually exclusive (e.g. use 'like' patterns on selectors or distinct template variables)
  3. Remove duplicate group definitions from the resource group configuration

Example fix

// before: groups "alice" and "${USER}" both expand to "alice"
// after: remove the static "alice" group and keep only "${USER}"
Defensive patterns

Strategy: validation

Validate before calling

// Pre-validate: expand all sibling name templates for sample contexts and assert uniqueness
Set<String> seen = new HashSet<>();
for (ResourceGroupSpec g : siblings) {
    if (!seen.add(g.getName().expandTemplate(context)))
        throw new IllegalStateException("Duplicate expanded name: " + g.getName());
}

Try / catch

try { manager.getMatchingSpec(group, context); } catch (IllegalStateException e) { log.error("Fix resource-groups.json: " + e.getMessage()); }

Prevention

When it happens

Trigger: Two root-level or sibling resource group specs whose (template-expanded) names both equal the same segment for a given query, e.g. two groups with templates like '${USER}' and a literal name that also expands to the same user.

Common situations: Overlapping selector/template configurations: a static group named 'alice' plus a template '${USER}' that also expands to 'alice'; duplicated entries in resource-groups.json.

Related errors

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/5940211d926c4656. Report an issue: GitHub.