Unauthorized to execute splitVector command

Error message

Unauthorized to execute splitVector command: {}, fallback to SampleSplitter

What it means

SplitVectorSplitStrategy runs the splitVector command to compute chunk-sized split keys. If MongoDB rejects the command with error code 13 (Unauthorized) via MongoCommandException, the strategy logs this warning and falls back to SampleBucketSplitter. The user lacks privileges to execute splitVector on the collection.

Solutions

Grant the connector user privileges to run splitVector (e.g. clusterManager role or a custom role with splitVector action).
Or select the SampleSplitter strategy explicitly instead of splitVector.
Test manually: db.runCommand({splitVector: "db.coll", keyPattern: {...}, maxChunkSizeBytes: N}).
Note some managed services disallow splitVector entirely — use sampling there.

Example fix

// mongosh: grant splitVector-capable role
use admin
db.grantRolesToUser("seaTunnelUser", [{role: "clusterManager", db: "admin"}])

Defensive patterns

Strategy: validation

Validate before calling

// mongosh: probe splitVector privilege upfront
const r = db.runCommand({splitVector: 'mydb.mycoll', keyPattern: {userId: 1}, maxChunkSizeBytes: 64*1024*1024});
print('ok=' + r.ok + ' errmsg=' + (r.errmsg || ''));

Prevention

Grant splitVector privilege (or clusterManager role) to the CDC user.
On managed services that block splitVector, choose the SampleSplitter strategy by default.
Pre-flight the command in mongosh with the exact keyPattern/chunk size.

When it happens

Trigger: split() calls splitVector(...) and the server responds with MongoCommandException errorCode == 13, e.g. user without splitVector privilege on the target namespace.

Common situations: Minimal-privilege users that can read data but not run admin/diagnostic commands; splitVector requires specific privileges often missing for app users; restricted deployments (Atlas, managed services) blocking splitVector.

Understand the failure class

Background: Permission denied / not authorized / 403 Forbidden: access-control rejections when the caller lacks the required role, grant, or ownership — this error's family across 18 libraries.

Authentication and authorization failures — expired tokens, bad credentials, and missing scopes.

Related errors

AI-assisted analysis of apache/seatunnel@cf67b549a7 (2026-09-10). Data as JSON: /api/errors/a2984334295bb171. Report an issue: GitHub.

Appendix: source

Thrown at seatunnel-connectors-v2/connector-cdc/connector-cdc-mongodb/src/main/java/org/apache/seatunnel/connectors/seatunnel/cdc/mongodb/source/splitters/SplitVectorSplitStrategy.java:67

@Slf4j
public enum SplitVectorSplitStrategy implements SplitStrategy {
    INSTANCE;

    @Override
    public Collection<SnapshotSplit> split(@Nonnull SplitContext splitContext) {
        MongoClient mongoClient = splitContext.getMongoClient();
        TableId collectionId = splitContext.getCollectionId();
        int chunkSizeMB = splitContext.getChunkSizeMB();

        BsonDocument keyPattern = new BsonDocument(ID_FIELD, new BsonInt32(1));

        BsonDocument splitResult;
        try {
            splitResult = splitVector(mongoClient, collectionId, keyPattern, chunkSizeMB);
        } catch (MongoCommandException e) {
            if (e.getErrorCode() == UNAUTHORIZED_ERROR) {
                log.warn(
                        "Unauthorized to execute splitVector command: {}, fallback to SampleSplitter",
                        e.getErrorMessage());
            } else {
                log.warn(
                        "Execute splitVector command failed: {}, fallback to SampleSplitter",
                        e.getErrorMessage());
            }
            return SampleBucketSplitStrategy.INSTANCE.split(splitContext);
        }

        if (!isCommandSucceed(splitResult)) {
            log.warn(
                    "Could not calculate standalone splits: {}, fallback to SampleSplitter",
                    splitResult.getString("errmsg"));
            return SampleBucketSplitStrategy.INSTANCE.split(splitContext);
        }

        BsonArray splitKeys = splitResult.getArray("splitKeys");

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