MOLT Replicator Commands and Flags

This page lists the commands and the flags that you can use to configure a MOLT Replicator command execution.

Commands

MOLT Replicator provides the following commands:

Command	Description
pglogical	Replicate from PostgreSQL source to CockroachDB target using logical replication.
mylogical	Replicate from MySQL source to CockroachDB target using GTID-based replication.
oraclelogminer	Replicate from Oracle source to CockroachDB target using Oracle LogMiner.
start	Replicate from CockroachDB source to PostgreSQL, MySQL, or Oracle target (). Requires a CockroachDB changefeed with rangefeeds enabled.
make-jwt	Generate JWT tokens for authorizing changefeed connections in failback scenarios. Supports signing tokens with RSA or EC keys, or generating claims for external JWT providers. For details, refer to .
version	Display version information and Go module dependencies with checksums. For details, refer to .

For command-specific flags and examples, refer to MOLT Replicator’s and documentation.

Flags

This page lists all available flags for the MOLT Replicator commands: start, pglogical, mylogical, oraclelogminer, and make-jwt.

Flag	Commands	Type	Description
-a, --allow	make-jwt	STRING	One or more database.schema identifiers. Can be repeated for multiple schemas.
--allowUnsupportedOracleVersion	oraclelogminer	BOOL	Use at your own risk. Starts replication to CockroachDB from an Oracle major version outside of the instead of failing at startup. Unsupported versions are not supported by Cockroach Labs and may cause silent data corruption or permanent data loss in the worst case. Only use this flag if you fully accept the risk and can validate data integrity yourself. Default: false
--applyTimeout	start, pglogical, mylogical, oraclelogminer	DURATION	The maximum amount of time to wait for an update to be applied. Default: 30s
--assumeIdempotent	start	BOOL	Disable the extra staging table queries that debounce non-idempotent redelivery in changefeeds.
--backfillFromSCN	oraclelogminer	INT	The SCN of the earliest active transaction at the time of the initial snapshot. Ensures no transactions are skipped when starting replication from Oracle.
--bestEffortOnly	start	BOOL	Eventually-consistent mode; useful for high-throughput, skew-tolerant schemas with .
--bestEffortWindow	start	DURATION	Use an eventually-consistent mode for initial backfill or when replication is behind; 0 to disable. Default: 1h0m0s
--bindAddr	start	STRING	The network address to bind to. Default: ":26258"
--claim	make-jwt	BOOL	If true, print a minimal JWT claim instead of signing.
--collapseMutations	start, pglogical, mylogical	BOOL	Combine multiple mutations on the same primary key within each batch into a single mutation. Default: true
--defaultGTIDSet	mylogical	STRING	Required the first time replicator is run. The default GTID set, in the format source_uuid:min(interval_start)-max(interval_end), which provides a replication marker for streaming changes.
--dataDir	start, pglogical, mylogical, oraclelogminer	STRING	Base directory for replicator data (for example, metrics snapshots). Default: "replicator-data"
--disableAuthentication	start	BOOL	Disable authentication of incoming Replicator requests; not recommended for production.
--disableFKAwareScheduling	start, pglogical, mylogical, oraclelogminer	BOOL	Disable Replicator’s default foreign-key-aware scheduling, which serializes target transactions that touch foreign-key-related rows so that a parent and its child rows commit in order, preventing potential transient foreign-key violation errors. Default: false
--discard	start	BOOL	Dangerous: Discard all incoming HTTP requests; useful for changefeed throughput testing. Not intended for production.
--discardDelay	start	DURATION	Adds additional delay in discard mode; useful for gauging the impact of changefeed round-trip time (RTT).
--dlqTableName	start, pglogical, mylogical, oraclelogminer	IDENT	The name of a table in the target schema for storing dead-letter entries. Default: replicator_dlq
--enableCheckpointStream	start	BOOL	Enable checkpoint streaming (use an internal changefeed from the staging table for real-time updates), rather than checkpoint polling (query the staging table for periodic updates), for failback replication. Default: false (use checkpoint polling)
--enableParallelApplies	start, pglogical, mylogical, oraclelogminer	BOOL	Enable parallel application of independent table groups during replication. By default, applies are synchronous. When enabled, this increases throughput at the cost of higher target pool usage and memory usage. Default: false
--fetchMetadata	mylogical	BOOL	Fetch column metadata explicitly, for older versions of MySQL that do not support binlog_row_metadata.
--flushPeriod	start, pglogical, mylogical, oraclelogminer	DURATION	Flush queued mutations after this duration. Default: 1s
--flushSize	start, pglogical, mylogical, oraclelogminer	INT	Ideal batch size to determine when to flush mutations. Default: 1000
--gracePeriod	start, pglogical, mylogical, oraclelogminer	DURATION	Allow background processes to exit. Default: 30s
--healthCheckTimeout	start	DURATION	The timeout for the health check endpoint. Default: 5s
--httpResponseTimeout	start	DURATION	The maximum amount of time to allow an HTTP handler to execute. Default: 2m0s
--ignoreDeletionsForTable	pglogical	STRING	Drop DELETE mutations for the named tables before buffering, to avoid memory pressure from large batch deletions already handled by target-side TTLs.
--immediate	start	BOOL	Bypass staging tables and write directly to target; recommended only for KV-style workloads with no .
-k, --key	make-jwt	STRING	The path to a PEM-encoded private key to sign the token with.
--limitLookahead	start	INT	Limit number of checkpoints to be considered when computing the resolving range; may cause replication to stall completely if older mutations cannot be applied.
--logDestination	start, pglogical, mylogical, oraclelogminer	STRING	Write logs to a file. If not specified, write logs to stdout.
--logFormat	start, pglogical, mylogical, oraclelogminer	STRING	Choose log output format: "fluent", "text". Default: "text"
--maxRetries	start, pglogical, mylogical, oraclelogminer	INT	Maximum number of times to retry a failed mutation on the target (for example, due to contention or a temporary unique constraint violation) before treating it as a hard failure. Default: 10
--metricsAddr	start, pglogical, mylogical, oraclelogminer	STRING	A :port or host:port on which to serve metrics and diagnostics. The metrics endpoint is http://{host}:{port}/_/varz.
--metricsSnapshotCompression	start, pglogical, mylogical, oraclelogminer	STRING	Compression for snapshot files: "gzip" or "none". Default: "gzip"
--metricsSnapshotPeriod	start, pglogical, mylogical, oraclelogminer	DURATION	How often to periodically store a metrics snaphot to files (for example, 15s, 1m). Set to 0 to disable. Default: 0
--metricsSnapshotRetentionSize	start, pglogical, mylogical, oraclelogminer	STRING	Delete oldest snapshots when the total size of the metrics-snapshots directory in the --dataDir exceeds this (for example, 100MB, 1GiB). Either this flag or --metricsSnapshotRetentionTime (or both) must be enabled. Default: ""
--metricsSnapshotRetentionTime	start, pglogical, mylogical, oraclelogminer	DURATION	Delete snapshots older than this duration (for example, 24h, 168h). 0 to disable. Either this flag or --metricsSnapshotRetentionSize (or both) must be enabled. Default: 168h
--ndjsonBufferSize	start	INT	The maximum amount of data to buffer while reading a single line of ndjson input; increase when source cluster has large blob values. Default: 65536
--oracle-application-users	oraclelogminer	STRING	List of Oracle usernames responsible for DML transactions in the PDB schema. Enables replication from the latest-possible starting point. Usernames are case-sensitive and must match the internal Oracle usernames (e.g., PDB_USER).
-o, --out	make-jwt	STRING	A file to write the token to.
--parallelism	start, pglogical, mylogical, oraclelogminer	INT	The number of concurrent database transactions to use. Default: 16
--publicationName	pglogical	STRING	The publication within the source database to replicate.
--quiescentPeriod	start, pglogical, mylogical, oraclelogminer	DURATION	How often to retry deferred mutations. Default: 10s
--replicationProcessID	mylogical	UINT32	The replication process ID to report to the source database. Default: 10
--retireOffset	start, pglogical, mylogical, oraclelogminer	DURATION	How long to delay removal of applied mutations. Default: 24h0m0s
--retryInitialBackoff	start, pglogical, mylogical, oraclelogminer	DURATION	Initial delay before the first retry attempt when applying a mutation to the target database fails due to a retryable error, such as contention or a temporary unique constraint violation. Default: 25ms
--retryMaxBackoff	start, pglogical, mylogical, oraclelogminer	DURATION	Maximum delay between retry attempts when applying mutations to the target database fails due to retryable errors. Default: 2s
--retryMultiplier	start, pglogical, mylogical, oraclelogminer	INT	Multiplier that controls how quickly the backoff interval increases between successive retries of failed applies to the target database. Default: 2
--scanSize	start, pglogical, mylogical, oraclelogminer	INT	The number of rows to retrieve from the staging database used to store metadata for replication. Default: 10000
--schemaRefresh	start, pglogical, mylogical, oraclelogminer	DURATION	How often a watcher will refresh its schema. If this value is zero or negative, refresh behavior will be disabled. Default: 1m0s
--scn	oraclelogminer	INT	Required the first time replicator is run. The snapshot System Change Number (SCN) from the initial data load, which provides a replication marker for streaming changes.
--scnWindowSize	oraclelogminer	INT	The maximum size of SCN bounds per pull iteration from LogMiner. This helps prevent timeout errors when processing large SCN ranges. Set to 0 or a negative value to disable the cap. Default: 3250
--slotName	pglogical	STRING	Required. PostgreSQL replication slot name. Must match the slot name specified with --pglogical-replication-slot-name in the . Default: "replicator"
--sourceConn	pglogical, mylogical, oraclelogminer	STRING	The source database’s connection string. When replicating from Oracle, this is the connection string of the Oracle container database (CDB).
--sourcePDBConn	oraclelogminer	STRING	Connection string for the Oracle pluggable database (PDB). Only required when using an Oracle multitenant configuration. --sourceConn must be included.
--sourceSchema	oraclelogminer	STRING	Required. Source schema name on Oracle where tables will be replicated from.
--stageDisableCreateTableReaderIndex	start, pglogical, mylogical, oraclelogminer	BOOL	Disable the creation of partial covering indexes to improve read performance on staging tables. Set to true if creating indexes on existing tables would cause a significant operational impact. Default: false
--stageMarkAppliedLimit	start, pglogical, mylogical, oraclelogminer	INT	Limit the number of mutations to be marked applied in a single statement. Default: 100000
--stageSanityCheckPeriod	start, pglogical, mylogical, oraclelogminer	DURATION	How often to validate staging table apply order (-1 to disable). Default: 10m0s
--stageSanityCheckWindow	start, pglogical, mylogical, oraclelogminer	DURATION	How far back to look when validating staging table apply order. Default: 1h0m0s
--stageUnappliedPeriod	start, pglogical, mylogical, oraclelogminer	DURATION	How often to report the number of unapplied mutations in staging tables (-1 to disable). Default: 1m0s
--stagingConn	start, pglogical, mylogical, oraclelogminer	STRING	The staging database’s connection string.
--stagingCreateSchema	start, pglogical, mylogical, oraclelogminer	BOOL	Automatically create the staging schema if it does not exist.
--stagingIdleTime	start, pglogical, mylogical, oraclelogminer	DURATION	Maximum lifetime of an idle connection. Default: 1m0s
--stagingJitterTime	start, pglogical, mylogical, oraclelogminer	DURATION	The time over which to jitter database pool disconnections. Default: 15s
--stagingMaxLifetime	start, pglogical, mylogical, oraclelogminer	DURATION	The maximum lifetime of a database connection. Default: 5m0s
--stagingMaxPoolSize	start, pglogical, mylogical, oraclelogminer	INT	The maximum number of staging database connections. Default: 128
--stagingSchema	start, pglogical, mylogical, oraclelogminer	STRING	Name of the CockroachDB schema that stores replication metadata. Required each time replicator is rerun after being interrupted, as the schema contains a checkpoint table that enables replication to resume from the correct transaction. Default: _replicator.public
--standbyTimeout	pglogical	DURATION	How often to report WAL progress to the source server. Default: 5s
--targetApplyQueueSize	pglogical, oraclelogminer	INT	Size of the apply queue that buffers mutations before they are written to the target database. Larger values can improve throughput, but increase memory usage. This flag applies only to PostgreSQL and Oracle sources, and replaces the deprecated --copierChannel and --stageCopierChannelSize flags.
--targetConn	start, pglogical, mylogical, oraclelogminer	STRING	The target database’s connection string.
--targetIdleTime	start, pglogical, mylogical, oraclelogminer	DURATION	Maximum lifetime of an idle connection. Default: 1m0s
--targetJitterTime	start, pglogical, mylogical, oraclelogminer	DURATION	The time over which to jitter database pool disconnections. Default: 15s
--targetMaxLifetime	start, pglogical, mylogical, oraclelogminer	DURATION	The maximum lifetime of a database connection. Default: 5m0s
--targetMaxPoolSize	start, pglogical, mylogical, oraclelogminer	INT	The maximum number of target database connections. Default: 128
--targetSchema	pglogical, mylogical, oraclelogminer	STRING	Required. The SQL database schema in the target cluster to update. CockroachDB schema names must be fully qualified in the format database.schema.
--targetStatementCacheSize	start, pglogical, mylogical, oraclelogminer	INT	The maximum number of prepared statements to retain. Default: 128
--taskGracePeriod	start, pglogical, mylogical, oraclelogminer	DURATION	How long to allow for task cleanup when recovering from errors. Default: 1m0s
--timestampLimit	start, pglogical, mylogical, oraclelogminer	INT	The maximum number of source timestamps to coalesce into a target transaction. Default: 1000
--tlsCertificate	start	STRING	A path to a PEM-encoded TLS certificate chain.
--tlsPrivateKey	start	STRING	A path to a PEM-encoded TLS private key.
--tlsSelfSigned	start	BOOL	If true, generate a self-signed TLS certificate valid for localhost.
--userscript	start, pglogical, mylogical, oraclelogminer	STRING	The path to a TypeScript configuration script. For example, --userscript 'script.ts'. For more information, refer to .
--userscriptQueueSize	start, pglogical, mylogical, oraclelogminer	INT	The number of mutations that can be buffered in the queue between the userscript source acceptor and the core sequencer’s copier. Tune this value to avoid replication bottlenecks when using userscripts. Default: 1000
-v, --verbose	start, pglogical, mylogical, oraclelogminer	COUNT	Increase logging verbosity. Use -v for debug logging or -vv for trace logging.