apache/beam · error · java.lang.UnsupportedOperationException

SideInputTable is a read-only metadata adapter and does not…

Error message

SideInputTable is a read-only metadata adapter and does not support snapshots.

What it means

SideInputTable wraps a frozen snapshot of Iceberg metadata for side-input use and deliberately rejects currentSnapshot(), since snapshot semantics require live metadata. Calling it throws UnsupportedOperationException. Use the snapshot captured at spec-creation time instead.

Solutions

  1. Obtain the snapshot from SerializableTableSpec / the original metadata rather than currentSnapshot().
  2. If the current snapshot is required, load the real table from the catalog instead of using SideInputTable.
  3. Guard with instanceof SideInputTable before calling snapshot methods.

Example fix

// before
Snapshot snap = sideInputTable.currentSnapshot();

// after
Snapshot snap = preloadedTable.currentSnapshot(); // catalog-backed table
Defensive patterns

Strategy: type-guard

Type guard

boolean hasCurrentSnapshot = !(table instanceof SideInputTable);

Try / catch

try {
  Snapshot s = table.currentSnapshot();
} catch (UnsupportedOperationException e) {
  if (!e.getMessage().contains("does not support snapshots")) throw e;
  // use the snapshot embedded in the SerializableTableSpec instead
}

Prevention

When it happens

Trigger: Calling table.currentSnapshot() on a SideInputTable deserialized inside a Beam worker.

Common situations: Code shared between live catalog tables and side-input tables; analytics helpers that always read the current snapshot; incorrect assumption that the adapter behaves like a full table.

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/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/985ff4ab6e609faf. Report an issue: GitHub.

Appendix: source

Thrown at sdks/java/io/iceberg/src/main/java/org/apache/beam/sdk/io/iceberg/SideInputTable.java:183

  @Override
  public FileIO io() {
    return spec.getFileIO();
  }

  @Override
  public EncryptionManager encryption() {
    return encryptionManager;
  }

  @Override
  public void refresh() {
    throw new UnsupportedOperationException(
        "SideInputTable is a read-only metadata adapter and does not support refresh.");
  }

  @Override
  public Snapshot currentSnapshot() {
    throw new UnsupportedOperationException(
        "SideInputTable is a read-only metadata adapter and does not support snapshots.");
  }

  @Override
  public Snapshot snapshot(long snapshotId) {
    throw new UnsupportedOperationException(
        "SideInputTable is a read-only metadata adapter and does not support snapshots.");
  }

  @Override
  public Iterable<Snapshot> snapshots() {
    throw new UnsupportedOperationException(
        "SideInputTable is a read-only metadata adapter and does not support snapshots.");
  }

  @Override
  public List<HistoryEntry> history() {
    throw new UnsupportedOperationException(

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