Use Percona Link for MongoDB¶
Percona Link for MongoDB doesn’t automatically start data replication after the startup. It has the idle status indicating that it is ready to accept requests.
You can interact with Percona Link for MongoDB using the command-line interface or via the HTTP API. Read more about PLM API.
Before you start¶
Your target MongoDB cluster may be empty or contain data. PLM replicates data from the source to the target but doesn’t manage the target’s data. If the target already has the same data as the source, PLM overwrites it. However, if the target contains different data, PLM doesn’t delete it during replication. This leads to inconsistencies between the source and target. To ensure consistency, manually delete any existing data from the target before starting replication.
Start the replication¶
Start the replication process between source and target clusters. PLM starts copying the data from the source to the target. First it does the initial sync by cloning the data and then applying all the changes that happened since the clone start.
Then it uses the change streams to track the changes to your data on the source and replicate them to the target.
$ plm start
Expected output
{
"ok": true
}
Send a POST request to the /start endpoint:
$ curl -X POST http://localhost:2242/start
Start the filtered replication¶
You can replicate the whole dataset or specific namespaces - databases and collections. You can specify what namespaces to include and/or exclude from the replication.
To include or exclude a specific database and all collections it includes, pass it in the format mydb.*.
$ plm start \
--include-namespaces="db1.collection1,db2.collection2" \
--exclude-namespaces="db3.collection3"
Expected output
{
"ok": true
}
Send a POST request to the /start endpoint:
$ curl -X POST http://localhost:2242/start -d '{
"includeNamespaces": ["db1.collection1", "db2.collection2"],
"excludeNamespaces": ["db3.collection3"]
}'
Pause the replication¶
You can pause the replication at any moment. PLM stops the replication, saves the timestamp and enters the paused state. PLM uses the saved timestamp after you resume the replication.
$ plm pause
Send a POST request to the /pause endpoint:
$ curl -X POST http://localhost:2242/pause
Resume the replication¶
Resume the replication. PLM changes the state to running and copies the changes that occurred to the data from the timestamp it saved when you paused the replication. Then it continues monitoring the data changes and replicating them real-time.
$ plm resume
Send a POST request to the /resume endpoint:
$ curl -X POST http://localhost:2242/resume
The replication may fail for some reason, like lost connectivity or the like. In this case you can resume replication by adding the --from-failure flag to the resume command:
$ plm resume --from-failure
Send a POST request to the /resume endpoint:
$ curl -X POST http://localhost:2242/resume -d '{
"fromFailure": true
}'
Check the replication status¶
Check the current status of the replication process.
$ plm status
Send a GET request to the /status endpoint:
$ curl http://localhost:2242/status
Finalize the replication¶
When you no longer need / want to replicate data, finalize the replication. PLM stops replication, creates the required indexes on the target, and stops. This is a one-time operation. You cannot restart the replicaton after you finalized it. If you run the start command, PLM will start the replication anew, with the initial sync.
$ plm finalize
Send a POST request to the /finalize endpoint:
$ curl -X POST http://localhost:2242/finalize
Created: September 8, 2025