apache/cassandra · error · InvalidRequestException

Duplicate column ' ' in CLUSTERING ORDER BY clause for table

Error message

Duplicate column '%s' in CLUSTERING ORDER BY clause for table '%s'

What it means

The CLUSTERING ORDER BY clause lists the same column more than once. The Raw builder tracks clustering order in a map keyed by column; put returning a non-null previous value means the column appeared twice, which makes the ordering ambiguous, so the statement is rejected.

Solutions

List each clustering column exactly once in CLUSTERING ORDER BY
Remove the duplicate entry, keeping the desired direction
Ensure all clustering columns that need non-default order are mentioned once each

Example fix

// before
CREATE TABLE t (a int, c int, PRIMARY KEY (a, c)) WITH CLUSTERING ORDER BY (c ASC, c DESC);
// after
CREATE TABLE t (a int, c int, PRIMARY KEY (a, c)) WITH CLUSTERING ORDER BY (c DESC);

Defensive patterns

Strategy: validation

Validate before calling

const orderCols = orderBy.map(o => o.column.toLowerCase());
if (new Set(orderCols).size !== orderCols.length) throw new Error('Duplicate column in CLUSTERING ORDER BY');

Try / catch

try { session.execute(ddl); } catch (e) { if (/in CLUSTERING ORDER BY/.test(e.message)) { /* de-duplicate the ORDER BY list and retry */ } else throw e; }

Prevention

List each clustering column once in CLUSTERING ORDER BY
De-duplicate ordering directives when merging DDL fragments
Cross-check ORDER BY columns against declared clustering columns

When it happens

Trigger: WITH CLUSTERING ORDER BY (c ASC, c DESC) in DDL; calling extendClusteringOrder twice for the same column identifier while building the statement raw.

Common situations: Generated DDL merging ordering directives from multiple sources; hand-written ORDER BY accidentally repeating a clustering column under different spellings that resolve to the same identifier.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/61f8a707f162542b. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/cql3/statements/schema/CreateTableStatement.java:678

        }

        public void setPartitionKeyColumns(List<ColumnIdentifier> columns)
        {
            if (null != partitionKeyColumns)
                throw ire("Multiple PRIMARY KEY specified for table '%s' (exactly one required)", name);

            partitionKeyColumns = columns;
        }

        public void markClusteringColumn(ColumnIdentifier column)
        {
            clusteringColumns.add(column);
        }

        public void extendClusteringOrder(ColumnIdentifier column, boolean ascending)
        {
            if (null != clusteringOrder.put(column, ascending))
                throw ire("Duplicate column '%s' in CLUSTERING ORDER BY clause for table '%s'", column, name);
        }
    }

    /**
     * Class encapsulating the properties of a column, which are its type and mask.
     */
    private final static class ColumnProperties
    {
        public final AbstractType<?> type;
        public final CQL3Type cqlType; // we keep the original CQL type for printing fully qualified user type names

        @Nullable
        public final ColumnMask mask;

        public ColumnProperties(AbstractType<?> type, CQL3Type cqlType, @Nullable ColumnMask mask)
        {
            this.type = type;
            this.cqlType = cqlType;

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