Userscript Quickstart

This quickstart guides you through creating, validating, and deploying your first userscript based on a cookbook example.

Before you begin

Install MOLT Replicator v1.3.0 or later for full compatibility with the userscript API.
Install a TypeScript-compatible IDE (for example, VS Code).

Step 1: Set up your environment

Create a new TypeScript file for your userscript in your IDE (for example, userscript.ts). For IDE autocomplete and type-checking support, optionally add the Replicator TypeScript definitions. For details, refer to Access this API.

Step 2: Write a userscript

Use the userscript cookbook as a starting point. The cookbook provides ready-to-use examples that you can copy and adapt. Copy and adapt a cookbook example that matches your use case. For example, adapt the template to filter a single table to exclude the audit_logs table from the public schema during replication:

import * as api from "replicator@v2";

const TARGET_SCHEMA_NAME = "defaultdb.public";
const TABLE_TO_SKIP = "audit_logs";

api.configureTargetSchema(TARGET_SCHEMA_NAME, {
  onRowUpsert: (row, meta) => {
    if (meta.table === TABLE_TO_SKIP) {
      return null; // Skip this table
    }
    return row;
  },
  onRowDelete: (row, meta) => {
    if (meta.table === TABLE_TO_SKIP) {
      return null;
    }
    return row;
  }
});

For details on the userscript API and handler functions, refer to the Userscript API.

When writing userscripts, follow the best practices.

Step 3: Use with Replicator

Include the --userscript flag to have MOLT Replicator apply the userscript. For example, to apply your userscript during PostgreSQL replication:

replicator pglogical \
--sourceConn $SOURCE \
--targetConn $TARGET \
--targetSchema defaultdb.public \
--slotName molt_slot \
--publicationName molt_fetch \
--stagingSchema defaultdb._replicator \
--stagingCreateSchema \
--userscript userscript.ts

Migration Considerations

MOLT Tools

Common Migration Approaches

Third-Party Migration Tools

Migrate Data Types

Userscript Quickstart

Before you begin

Step 1: Set up your environment

Step 2: Write a userscript

Step 3: Use with Replicator

See also

​Before you begin

​Step 1: Set up your environment

​Step 2: Write a userscript

​Step 3: Use with Replicator

​See also

Before you begin

Step 1: Set up your environment

Step 2: Write a userscript

Step 3: Use with Replicator

See also