apache/druid · error · UnsupportedOperationException

Vectorized matcher cannot make object matcher for ARRAY type

Error message

Vectorized matcher cannot make object matcher for ARRAY types

What it means

ArrayVectorValueMatcher cannot build an object-value matcher for ARRAY columns in the vectorized engine; comparing whole array objects against a match value is unsupported, so makeMatcher(Object, ColumnType) unconditionally throws UnsupportedOperationException.

Source

Thrown at processing/src/main/java/org/apache/druid/query/filter/vector/ArrayVectorValueMatcher.java:56

      VectorObjectSelector selector
  )
  {
    this.columnType = columnType;
    this.selector = selector;
  }

  @Override
  public VectorValueMatcher makeMatcher(@Nullable String value)
  {
    throw new UnsupportedOperationException(
        "Vectorized matcher cannot make string matcher for ARRAY types"
    );
  }

  @Override
  public VectorValueMatcher makeMatcher(Object matchValue, ColumnType matchValueType)
  {
    throw new UnsupportedOperationException(
        "Vectorized matcher cannot make object matcher for ARRAY types"
    );
  }

  @Override
  public VectorValueMatcher makeMatcher(DruidPredicateFactory predicateFactory)
  {
    final DruidObjectPredicate<Object[]> predicate = predicateFactory.makeArrayPredicate(columnType);
    return new BaseVectorValueMatcher(selector)
    {
      final VectorMatch match = VectorMatch.wrap(new int[selector.getMaxVectorSize()]);

      @Override
      public ReadableVectorMatch match(final ReadableVectorMatch mask, boolean includeUnknown)
      {
        final Object[] vector = selector.getObjectVector();
        final int[] selection = match.getSelection();

View on GitHub (pinned to 9b90983fd2)

Solutions

Use a DruidPredicateFactory matcher (makeMatcher(DruidPredicateFactory)) which is supported for array vectors, or filter on unnested columns.
Turn off vectorization for the query (set vectorize=false in the query context) to use the non-vectorized array comparison path.
Express the filter as an array-aware filter (e.g. via SQL ARRAY functions compiled to supported filters).

Example fix

// before
vectorMatcher.makeMatcher(arrayValueList, ColumnType.ofArray(...));
// after
vectorMatcher.makeMatcher(v -> v != null && v.equals(expectedArray)); // DruidPredicateFactory path, or disable vectorization

Defensive patterns

Strategy: validation

Validate before calling

if (columnType.isArray() && matchValue != null) { /* route to predicate-based or non-vectorized path */ }

Type guard

boolean supportsObjectMatcher = !columnType.isArray();

Try / catch

try { matcher = arrayMatcher.makeMatcher(matchValue, matchValueType); } catch (UnsupportedOperationException e) { matcher = null; /* fallback path */ }

Prevention

Avoid object-value equality filters on ARRAY columns under vectorization
Use predicate-factory matchers for array vectors
Force non-vectorized execution for array-equality queries

When it happens

Trigger: Vectorized selector/in-style filters supplying an object match value (e.g. a List for array comparison) against an ARRAY-typed column.

Common situations: Attempts to vectorize array-equality filters; internal engine paths choosing the vector engine for queries filtering ARRAY columns by value.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/1d5591fdf771e538. Report an issue: GitHub.