apache/cassandra · error · InvalidRequestException

Invalid slice selection

Error message

Invalid slice selection: %s of type %s is not a collection

What it means

Thrown when preparing a slice selection (collection[lo..hi]) if the selected column's type, after unwrapping ReversedType, is not a CollectionType. Slice access over element ranges only exists for collections, so applying it to any other type is rejected.

Solutions

1. Confirm the column is a collection (list/set/map) before using [x..y] slice syntax
2. Select the full column and slice in application code
3. Cast or re-model the column as a collection if range access is genuinely needed

Example fix

// before
SELECT scalar_col[0..3] FROM ks.tbl;
// after
SELECT list_col[0..3] FROM ks.tbl;  -- list_col must be a list/set/map

// verify column is a collection before slice access
String type = getColumnType(keyspace, table, column);
if (!type.matches("(list|set|map).*")) throw new IllegalArgumentException(column + " is not a collection; cannot use [lo..hi]");

try { session.execute(sliceSelect); } catch (InvalidRequestException e) { if (e.getMessage().contains("is not a collection")) { /* fall back to selecting whole column */ } else throw e; }

When it happens

Trigger: SELECT mycol[0..5] or mycol['a'..'z'] where mycol's effective type is not a list/set/map.

Common situations: Using list-slice syntax on a scalar or UDT column; schema migration changed the column type; confusion between frozen and non-frozen collection slicing support.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• appendAll() can only be called on non-frozen collections
• Invalid element selection
• Cannot create index on
• Cannot create () index on frozen column . Frozen…
• Cannot create () index on . Non-collection columns only…

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/0a90f4abc2d123e3. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/cql3/selection/Selectable.java:1566

        @Override
        public String toString()
        {
            return String.format("%s[%s..%s]", selected, from == null ? "" : from, to == null ? "" : to);
        }

        public Selector.Factory newSelectorFactory(TableMetadata cfm, AbstractType<?> expectedType, List<ColumnMetadata> defs, VariableSpecifications boundNames)
        {
            // Note that a slice gives you the same type as the collection you applied it to, so we can pass expectedType for selected directly
            Selector.Factory factory = selected.newSelectorFactory(cfm, expectedType, defs, boundNames);
            ColumnSpecification receiver = factory.getColumnSpecification(cfm);

            AbstractType<?> type = receiver.type;
            if (receiver.isReversedType())
            {
                type = ((ReversedType<?>) type).baseType;
            }
            if (!(type instanceof CollectionType))
                throw new InvalidRequestException(String.format("Invalid slice selection: %s of type %s is not a collection", selected, type.asCQL3Type()));

            ColumnSpecification boundSpec = specForElementOrSlice(selected, receiver, ((CollectionType) type).kind, "Slice");

            // If from or to are null, this means the user didn't provide on in the syntax (we had c[x..] or c[..x]).
            // The equivalent of doing this when preparing values would be to use UNSET.
            Term f = from == null ? Constants.UNSET_VALUE : from.prepare(cfm.keyspace, boundSpec);
            Term t = to == null ? Constants.UNSET_VALUE : to.prepare(cfm.keyspace, boundSpec);
            f.collectMarkerSpecification(boundNames, cfm);
            t.collectMarkerSpecification(boundNames, cfm);
            return ElementsSelector.newSliceFactory(toString(), factory, (CollectionType)type, f, t);
        }

        public AbstractType<?> getExactTypeIfKnown(String keyspace)
        {
            AbstractType<?> selectedType = selected.getExactTypeIfKnown(keyspace);
            if (selectedType == null || !(selectedType instanceof CollectionType))
                return null;

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