{"record":{"id":"c8ff23e753418c4c","repo":"apache/druid","slug":"stringfirstaggregator-does-not-support-getlong-c8ff23","errorCode":null,"errorMessage":"StringFirstAggregator does not support getLong()","messagePattern":"StringFirstAggregator does not support getLong\\(\\)","errorType":"exception","errorClass":"java.lang.UnsupportedOperationException","httpStatus":null,"severity":"error","filePath":"processing/src/main/java/org/apache/druid/query/aggregation/firstlast/first/StringFirstBufferAggregator.java","lineNumber":121,"sourceCode":"    }\n  }\n\n  @Override\n  public Object get(ByteBuffer buf, int position)\n  {\n    return StringFirstLastUtils.readPair(buf, position);\n  }\n\n  @Override\n  public float getFloat(ByteBuffer buf, int position)\n  {\n    throw new UnsupportedOperationException(\"StringFirstAggregator does not support getFloat()\");\n  }\n\n  @Override\n  public long getLong(ByteBuffer buf, int position)\n  {\n    throw new UnsupportedOperationException(\"StringFirstAggregator does not support getLong()\");\n  }\n\n  @Override\n  public double getDouble(ByteBuffer buf, int position)\n  {\n    throw new UnsupportedOperationException(\"StringFirstAggregator does not support getDouble()\");\n  }\n\n  @Override\n  public void close()\n  {\n    // no resources to cleanup\n  }\n\n  @Override\n  public void inspectRuntimeShape(RuntimeShapeInspector inspector)\n  {\n    inspector.visit(\"timeSelector\", timeSelector);","sourceCodeStart":103,"sourceCodeEnd":139,"githubUrl":"https://github.com/apache/druid/blob/9b90983fd291f26935af934383ce360473179e4d/processing/src/main/java/org/apache/druid/query/aggregation/firstlast/first/StringFirstBufferAggregator.java#L103-L139","documentation":"StringFirstBufferAggregator's per-group cell holds a serialized string pair, so getLong(ByteBuffer,int) is unsupported and always throws UnsupportedOperationException. Numeric long reads of string-first aggregates are invalid.","triggerScenarios":"Calling getLong(buf, position) on a StringFirstBufferAggregator — e.g. code path assuming long-typed aggregator output, or outputType LONG configured for stringFirst with buffer aggregation enabled.","commonSituations":"Vectorized/buffered group-by queries with a numeric outputType on stringFirst; generic result-reading utilities calling getLong for all aggregators.","solutions":["Use get(buf, position) to obtain the deserialized string pair.","Correct the outputType or post-aggregator to expect a string.","Switch to longFirst aggregation when a numeric earliest value is required.","Branch on aggregator type before calling numeric getters."],"exampleFix":"// before\nlong v = bufAggregator.getLong(buf, pos);\n// after\nObject v = bufAggregator.get(buf, pos); // SerializablePairLongString","handlingStrategy":"type-guard","validationCode":"if (bufAggregator instanceof StringFirstBufferAggregator) {\n  Object v = bufAggregator.get(buf, position);\n} else {\n  long v = bufAggregator.getLong(buf, position);\n}","typeGuard":"boolean supportsLong(BufferAggregator a) {\n  return !(a instanceof StringFirstBufferAggregator);\n}","tryCatchPattern":"try {\n  return agg.getLong(buf, pos);\n} catch (UnsupportedOperationException e) {\n  Object pair = agg.get(buf, pos);\n  return pair == null ? 0L : Long.parseLong(String.valueOf(((SerializablePairLongString) pair).rhs));\n}","preventionTips":["Do not declare LONG outputType for stringFirst in buffered queries.","Use longFirst for long results.","Branch on aggregator type in generic result readers."],"tags":["druid","aggregation","buffer-aggregator","unsupported-getter"],"backgroundTag":"unsupported-operation","analyzedSha":"9b90983fd291f26935af934383ce360473179e4d","analyzedAt":"2026-09-07T13:32:30.957Z","contentChangedAt":"2026-09-07T13:32:30.957Z","schemaVersion":2},"datasetVersion":"2026-09-14T05:17:10.506Z"}