prestodb/presto · error · PrestoException

NOT_SUPPORTED

NOT_SUPPORTED

Error message

Unsupported explain plan type %s for JSON format

What it means

QueryExplainer.getJsonPlan can only render LOGICAL or DISTRIBUTED plans in JSON explain format. If the session's explain plan type is anything else (e.g. IO, VALIDATE, or an unknown type), it falls through the switch's default branch and throws NOT_SUPPORTED, because there is no JSON rendering for that plan type.

Source

Thrown at presto-main-base/src/main/java/com/facebook/presto/sql/analyzer/QueryExplainer.java:199

        DataDefinitionTask<?> task = dataDefinitionTask.get(statement.getClass());
        if (task != null) {
            // todo format as json
            return explainTask(statement, task, parameters);
        }

        Plan plan;
        switch (planType) {
            case IO:
                plan = getLogicalPlan(session, statement, parameters, warningCollector, query, viewDefinitionReferences);
                return textIOPlan(plan.getRoot(), metadata, session);
            case LOGICAL:
                plan = getLogicalPlan(session, statement, parameters, warningCollector, query, viewDefinitionReferences);
                return jsonLogicalPlan(plan.getRoot(), plan.getTypes(), metadata.getFunctionAndTypeManager(), plan.getStatsAndCosts(), session);
            case DISTRIBUTED:
                SubPlan subPlan = getDistributedPlan(session, statement, parameters, warningCollector, query, viewDefinitionReferences);
                return jsonDistributedPlan(subPlan, metadata.getFunctionAndTypeManager(), session);
            default:
                throw new PrestoException(NOT_SUPPORTED, format("Unsupported explain plan type %s for JSON format", planType));
        }
    }

    public Plan getLogicalPlan(Session session, Statement statement, List<Expression> parameters, WarningCollector warningCollector, String query, ViewDefinitionReferences viewDefinitionReferences)
    {
        return getLogicalPlan(session, statement, parameters, warningCollector, new PlanNodeIdAllocator(), query, viewDefinitionReferences);
    }

    public Plan getLogicalPlan(Session session, Statement statement, List<Expression> parameters, WarningCollector warningCollector, PlanNodeIdAllocator idAllocator, String query, ViewDefinitionReferences viewDefinitionReferences)
    {
        // analyze statement
        Analysis analysis = session.getRuntimeStats()
                .recordWallAndCpuTime(ANALYZE_TIME_NANOS, () -> analyze(session, statement, parameters, warningCollector, query, viewDefinitionReferences));

        final VariableAllocator planVariableAllocator = new VariableAllocator();
        LogicalPlanner logicalPlanner = new LogicalPlanner(
                session,
                idAllocator,

View on GitHub (pinned to 55bb57d202)

Solutions

1. Use TYPE LOGICAL or TYPE DISTRIBUTED with EXPLAIN (FORMAT JSON)
2. Drop the TYPE clause so the default (distributed) plan type is used
3. Render unsupported plan types with the default text format instead of JSON

Example fix

// before
EXPLAIN (TYPE VALIDATE, FORMAT JSON) SELECT 1;
// after
EXPLAIN (TYPE DISTRIBUTED, FORMAT JSON) SELECT 1;

EnumSet<ExplainType.Type> jsonSupported = EnumSet.of(ExplainType.Type.LOGICAL, ExplainType.Type.DISTRIBUTED);
if (!jsonSupported.contains(explainType)) {
    throw new IllegalArgumentException("FORMAT JSON only supports TYPE LOGICAL or TYPE DISTRIBUTED");
}

boolean supportsJsonPlan(ExplainType.Type type) { return type == ExplainType.Type.LOGICAL || type == ExplainType.Type.DISTRIBUTED; }

try { return explainer.getJsonExplainPlan(...); } catch (PrestoException e) { if (e.getErrorCode().getCode() == NOT_SUPPORTED.toErrorCode().getCode()) { /* fall back to text format */ } else { throw e; } }

When it happens

Trigger: Running 'EXPLAIN (FORMAT JSON, TYPE <unsupported>) ...' where the explain TYPE is not LOGICAL or DISTRIBUTED, e.g. TYPE VALIDATE or TYPE IO with FORMAT JSON.

Common situations: Combining EXPLAIN FORMAT JSON with plan types that only have text renderings; copying an EXPLAIN invocation and changing FORMAT without adjusting TYPE.

Understand the failure class

Background: Presto NOT_SUPPORTED error: what "not supported" means and how to fix it — this error's family across 3 libraries.

Related errors

• INVALID_TABLE_PROPERTY
• NOT_SUPPORTED
• NOT_SUPPORTED
• NOT_SUPPORTED
• NOT_SUPPORTED

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/50884d025a2001e7. Report an issue: GitHub.