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molt-replicator

Replicates ongoing database changes from PostgreSQL, MySQL, or Oracle to CockroachDB via CDC.

2|1|Updated Mar 11, 2026
Search Tags:#postgresql#database migration#replication#mysql#cdc#cockroachdb#cutover
One-click install
npx skills add https://github.com/cockroachdb/cursor-plugin --skill molt-replicator-cockroachdb
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: molt-replicator
Source: https://github.com/cockroachdb/cursor-plugin/tree/main/skills/cockroachdb-onboarding-and-migrations/molt-replicator
Command: npx skills add https://github.com/cockroachdb/cursor-plugin --skill molt-replicator-cockroachdb

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve? After an initial bulk data load with molt fetch, source databases keep receiving writes. This Skill guides you through setting up continuous change-data-capture replication so your CockroachDB target stays in sync until cutover, eliminating manual delta-migration guesswork. ## Core Features & Use Cases - Multi-source CDC replication: Configure pglogical for PostgreSQL, mylogical for MySQL, oraclelogminer for Oracle, plus Kafka, object storage, and CockroachDB CDC sources. - Staged apply architecture: Buffer changes in a _replicator staging schema on the target cluster before applying them to target tables, with dead-letter-queue support for failed rows. - Full cutover workflow: Step-by-step guidance from molt fetch bulk load through publication/slot setup, preflight connectivity checks, lag monitoring via Prometheus metrics, and final cutover. - Use Case: You are migrating a production PostgreSQL database to CockroachDB. After running molt fetch for the initial load, use this Skill to start replicator pglogical, monitor replication lag on the metrics endpoint, and execute a low-lag cutover. ## Quick Start Ask the AI to walk you through starting replicator pglogical against your source PostgreSQL and target CockroachDB after a molt fetch load, including staging database creation and lag monitoring.

Frequently Asked Questions about molt-replicator

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I replicate changes from PostgreSQL to CockroachDB after molt fetch?▼

Run replicator pglogical with --publicationName matching the publication molt fetch created (default molt_fetch), plus --sourceConn, --stagingConn, and --targetConn. Create the _replicator staging database on the target first, then monitor lag via the Prometheus metrics endpoint.

What is the difference between molt fetch and replicator?▼

molt fetch performs the one-time bulk data load, while replicator is a separate binary that continuously captures and applies ongoing changes. The data-load-and-replication mode in molt fetch is deprecated; run replicator directly after fetch completes.

Does replicator support MySQL and Oracle sources?▼

Yes, replicator mylogical handles MySQL sources requiring ROW binlog format and GTID mode, and replicator oraclelogminer handles Oracle requiring archive log mode and supplemental logging. It also supports Kafka, cloud object storage, and CockroachDB CDC sources.

Why is my replication slot name mismatch causing failures?▼

The --publicationName and --slotName on replicator must match what molt fetch created. molt fetch defaults the publication to molt_fetch but has no default slot name, while replicator defaults --slotName to replicator, so set both explicitly on both sides.

What are the limitations of running replicator long-term?▼

Replicator holds an open replication slot on the source, which blocks WAL cleanup and can grow source disk usage. The dead-letter-queue table also grows over time and needs periodic purging, and there is no built-in alerting so you must configure external alerts on the metrics endpoint.

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