MongoDB target

TwinCommit applies changes to MongoDB with bulkWrite upserts. The document _id comes from the source primary key. Each batch and its checkpoint document are written in one multi-document transaction, so delivery is exactly-once.

Supported: MongoDB 6.0, 7.0 and 8.x replica sets and sharded clusters · MongoDB Atlas.

Configuration

target:
  type: mongodb
  uri: mongodb+srv://twincommit:${MONGO_TARGET_PASSWORD}@cluster1.example.mongodb.net/
  database: replica
  id_field: _id            # single-column PKs map to _id; composite PKs become an embedded document
  nest: []                 # optional: embed child tables, see below

How apply works

• Inserts and updates become replaceOne with upsert: true, filtered on _id.
• Deletes become deleteOne.
• The batch and the checkpoint document in state_schema are committed in one transaction.

Embedding child tables

Use nest to embed rows from a child table as an array in the parent document:

  nest:
    - parent: SALES.ORDERS
      child: SALES.ORDER_LINES
      field: lines
      join: [ORDER_ID]

Roles

db.getSiblingDB("admin").createUser({
  user: "twincommit", pwd: "********",
  roles: [{ role: "readWrite", db: "replica" }]
})