apache/druid · error · IllegalArgumentException

No such virtual column

Error message

No such virtual column[%s]

What it means

VirtualColumns throws IAE when a selector requests a virtual column by name that does not exist in the VirtualColumns instance. It is a lookup failure: getVirtualColumn returned null for the requested columnName, meaning no virtual column with that name was configured.

Solutions

1. Verify the column name is exactly the virtual column alias defined in the query/virtualColumns list (case-sensitive)
2. Add or correct the virtual column definition in the query's virtualColumns block so the name exists
3. If the column should be a regular column, remove it from the virtual-columns reference and use it directly

Example fix

// before
VirtualColumns.of("concat_expr") // referenced as "concat" in the filter
// after
// reference the alias exactly: filters on "concat_expr" or define the virtual column with the alias used in the query

if (!knownVirtualColumnNames.contains(columnName)) { throw new IllegalArgumentException("Unknown virtual column: " + columnName); }
VirtualColumns.of(...).getVirtualColumnForSelector(columnName);

try { VirtualColumn vc = virtualColumns.virtualColumnForSelector(name); } catch (IAE e) { /* fall back to regular column lookup */ }

When it happens

Trigger: Calling VirtualColumns.getVirtualColumnForSelector(columnName) (directly or via virtualColumn(...)) with a name that is not a registered virtualized column.

Common situations: Typo in the column name in a Druid query or ingestion spec; referencing a virtual column expression by its alias before it is defined; query referencing a column removed between query versions; SQL planner passing a name that only exists in a different VirtualColumns scope.

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

• No such sink
• Self-referential column
• A-Not-B requires at least 1 sketch
• Access-Check-Result
• Action [ ] failed for worker [ ] with status ( )

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/ee63dc62b7f6e06d. Report an issue: GitHub.

Appendix: source

Thrown at processing/src/main/java/org/apache/druid/segment/VirtualColumns.java:553

    // id doesn't matter as there is only one kind of "VirtualColumns", so use 0.
    return new CacheKeyBuilder((byte) 0).appendCacheablesIgnoringOrder(virtualColumns).build();
  }

  public boolean isEmpty()
  {
    return virtualColumns.isEmpty();
  }

  public List<String> getColumnNames()
  {
    return virtualColumnNames;
  }

  private VirtualColumn getVirtualColumnForSelector(String columnName)
  {
    VirtualColumn virtualColumn = getVirtualColumn(columnName);
    if (virtualColumn == null) {
      throw new IAE("No such virtual column[%s]", columnName);
    }
    return virtualColumn;
  }

  /**
   * Detects cycles in the dependencies of a {@link VirtualColumn}.
   *
   * @param virtualColumn virtual column to check
   * @param visited       null on initial call. Internally, this method operates recursively, and uses this parameter
   *                      to pass down the list of already-visited columns.
   */
  private void detectCycles(VirtualColumn virtualColumn, @Nullable Set<String> visited)
  {
    // Copy "visited" to avoid modifying it
    final Set<String> visitedCopy = visited == null
                                    ? Sets.newHashSet(virtualColumn.getOutputName())
                                    : Sets.newHashSet(visited);

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