{"record":{"id":"68290301de3dc8f9","repo":"apache/cassandra","slug":"cannot-get-comparator-s-in-s-this-might-due-to","errorCode":null,"errorMessage":"Cannot get comparator %s in %s. This might due to a mismatch between the schema and the data read","messagePattern":"Cannot get comparator (.+?) in (.+?)\\. This might due to a mismatch between the schema and the data read","errorType":"exception","errorClass":"RuntimeException","httpStatus":null,"severity":"critical","filePath":"src/java/org/apache/cassandra/db/marshal/CompositeType.java","lineNumber":202,"sourceCode":"    @Override\n    public TypeSerializer<ByteBuffer> getSerializer()\n    {\n        return serializer;\n    }\n\n    protected <V> AbstractType<?> getComparator(int i, V value, ValueAccessor<V> accessor, int offset)\n    {\n        try\n        {\n            return types.get(i);\n        }\n        catch (IndexOutOfBoundsException e)\n        {\n            // We shouldn't get there in general we shouldn't construct broken composites\n            // but there is a few cases where if the schema has changed since we created/validated\n            // the composite, this will be thrown (see #6262). Those cases are a user error but\n            // throwing a more meaningful error message to make understanding such error easier. .\n            throw new RuntimeException(\"Cannot get comparator \" + i + \" in \" + this + \". \"\n                                     + \"This might due to a mismatch between the schema and the data read\", e);\n        }\n    }\n\n    protected <VL, VR> AbstractType<?> getComparator(int i, VL left, ValueAccessor<VL> accessorL, VR right, ValueAccessor<VR> accessorR, int offsetL, int offsetR)\n    {\n        return getComparator(i, left, accessorL, offsetL);\n    }\n\n    protected <V> AbstractType<?> getAndAppendComparator(int i, V value, ValueAccessor<V> accessor, StringBuilder sb, int offset)\n    {\n        return types.get(i);\n    }\n\n    @Override\n    public <V> ByteSource asComparableBytes(ValueAccessor<V> accessor, V data, Version version)\n    {\n        if (data == null || accessor.isEmpty(data))","sourceCodeStart":184,"sourceCodeEnd":220,"githubUrl":"https://github.com/apache/cassandra/blob/88fd0f6a0eaed8943f05ac9e8f947882b8ddc8f1/src/java/org/apache/cassandra/db/marshal/CompositeType.java#L184-L220","documentation":"CompositeType.getComparator(i) indexes into the composite's configured type list; if the serialized composite has more components than the current type list, IndexOutOfBoundsException is caught and rethrown as this RuntimeException. It signals that the on-disk composite was written under a different (older) schema than the one now being used to read it (CASSANDRA-6262).","triggerScenarios":"Reading a cell whose composite value has more parts than types.size() after the CompositeType definition was altered (e.g. columns dropped or the comparator redefined); calling getComparator(int i) with i beyond the type list.","commonSituations":"Schema changes to clustered-column comparators without rewriting SSTables; restoring snapshots under a modified schema; upgrades where the comparator definition drifted from data.","solutions":["Restore the original schema (re-add the removed composite types) so the data matches","Rewrite the affected SSTables (e.g. scrub/upgrade or REWRITE) under the current schema","Verify with sstablemetadata/sstabledump that the composite layout matches the schema","Restore from a backup taken before the schema change"],"exampleFix":null,"handlingStrategy":"try-catch","validationCode":null,"typeGuard":null,"tryCatchPattern":"try { type.getComparator(i); } catch (RuntimeException e) { if (e.getMessage().startsWith(\"Cannot get comparator\")) { /* schema/data mismatch: restore schema or rewrite sstables */ } else throw e; }","preventionTips":["Never alter composite/comparator definitions in place; create new tables","Keep schema backups before comparator changes","Audit SSTables with sstabledump after schema migrations"],"tags":["schema","composite","data-corruption"],"backgroundTag":"schema-mismatch-between-data-and-schema","analyzedSha":"88fd0f6a0eaed8943f05ac9e8f947882b8ddc8f1","analyzedAt":"2026-09-10T07:29:22.284Z","contentChangedAt":"2026-09-10T07:29:22.284Z","schemaVersion":2},"datasetVersion":"2026-09-17T15:17:12.973Z"}