prestodb/presto · error · ParseError

{parse_error} ConnectorMergeTableHandle ConnectorMergeTable

Error message

{parse_error} ConnectorMergeTableHandle  ConnectorMergeTableHandle

What it means

This ParseError is thrown while deserializing JSON into a shared_ptr<ConnectorMergeTableHandle>. Here a JsonEncodedSubclass key reader raises json::parse_error while extracting the subclass key, re-thrown as ParseError labeled 'ConnectorMergeTableHandle'. The merge handle JSON (used for MERGE/MERGE-DELETE plans) is syntactically invalid before connector-protocol dispatch.

Source

Thrown at presto-native-execution/presto_cpp/presto_protocol/core/presto_protocol_core.cpp:7578

// UPDATE/MERGE deserialization on the worker (MergeHandle.from_json ->
// from_json_key(connectorMergeTableHandle) reaches here). Unlike the Delete/
// Insert handles there is no deserialize(ConnectorMergeTableHandle) overload
// on ConnectorProtocol, so the customSerializedValue branch is omitted.
void to_json(json& j, const std::shared_ptr<ConnectorMergeTableHandle>& p) {
  if (p == nullptr) {
    return;
  }
  String type = p->_type;
  getConnectorProtocol(type).to_json(j, p);
}

void from_json(const json& j, std::shared_ptr<ConnectorMergeTableHandle>& p) {
  String type;
  try {
    JsonEncodedSubclass keyReader;
    type = keyReader.getSubclassKey(j);
  } catch (json::parse_error& e) {
    throw ParseError(
        std::string(e.what()) +
        " ConnectorMergeTableHandle  ConnectorMergeTableHandle");
  }

  getConnectorProtocol(type).from_json(j, p);
}
} // namespace facebook::presto::protocol
namespace facebook::presto::protocol {
MergeHandle::MergeHandle() noexcept {
  _type = "MergeHandle";
}

void to_json(json& j, const MergeHandle& p) {
  j = json::object();
  j["@type"] = "MergeHandle";
  to_json_key(
      j,
      "tableHandle",

View on GitHub (pinned to 55bb57d202)

Solutions

1. Check that native execution supports the MERGE protocol version in use; align coordinator and native worker versions
2. Validate the merge handle JSON fragment with a standalone parser to find the syntax error
3. Fix the connector-side ConnectorMergeTableHandle JSON encoding
4. Log the full plan JSON for the MERGE statement and reproduce the parse in isolation

Example fix

// before
proto::from_json(mergeHandleJson, mergeHandle);
// after
json j = json::parse(mergeHandleJson);
if (!j.contains("type")) throw std::runtime_error("missing merge handle type");
proto::from_json(j, mergeHandle);

json j = json::parse(mergeHandleJson);
if (!j.is_object() || !j.contains("type")) {
  throw std::runtime_error("ConnectorMergeTableHandle JSON invalid: missing 'type'");
}
// also confirm native side supports the merge protocol
if (!supportsMergeProtocol()) throw std::runtime_error("native merge protocol not supported");

bool isWellFormedMergeHandleJson(const json& j) {
  return j.is_object() && j.contains("type") && j["type"].is_string();
}

try {
  proto::from_json(j, mergeHandle);
} catch (const ParseError& e) {
  LOG(ERROR) << "bad ConnectorMergeTableHandle JSON: " << e.what();
  throw;
}

When it happens

Trigger: from_json invoked when deserializing a MERGE plan fragment whose ConnectorMergeTableHandle JSON is malformed; the JsonEncodedSubclass key extraction fails before getConnectorProtocol(type) dispatch.

Common situations: Running MERGE statements with a coordinator/native version mismatch (merge support newer on one side); connector with broken merge-handle serialization; corrupted plan JSON.

Understand the failure class

Background: JSON parse error: "Unexpected token" / "not valid JSON" / "failed to parse" — what JSON parsers are really complaining about — this error's family across 45 libraries.

Related errors

• {parse_error} ConnectorIndexHandle ConnectorIndexHandle
• {parse_error} ColumnHandle ColumnHandle
• {parse_error} ConnectorTableLayoutHandle ConnectorTableLayo
• {parse_error} ConnectorInsertTableHandle ConnectorInsertTab
• (JsonMappingException cause message)

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/14e5a865cb63fa09. Report an issue: GitHub.