Start here
What Trellara is
PostgreSQL already moves changes. Logical replication decodes the WAL, streams committed changes to a subscriber, and does it well enough that most teams need nothing else. Trellara exists for what happens after that stops being enough.
What it does
Trellara consumes native logical replication through the standard protocol and adds three things Postgres does not provide:
- It moves retention pressure off your primary. A stalled consumer holds a replication slot, and the slot holds WAL on the database serving your customers. Trellara publishes to a durable boundary of its own and only then advances the source checkpoint, so a stalled consumer stalls against Trellara's disk rather than yours.
- It keeps the transaction boundary. A committed PostgreSQL transaction stays one unit through capture, transport and apply, rather than dissolving into independent row events that nobody reassembles.
- It can prove convergence. Row counts, primary-key checksums and source-to-target watermarks, compared on demand, returning evidence rather than a lag number.
What it is not
Trellara has no transformation engine, no scheduler, no catalog of its own, no phone-home telemetry, and no requirement that you adopt a different PostgreSQL distribution. It moves what Postgres committed and proves where it landed.
It is also not a replacement for logical replication. It is a consumer of it. If native replication stops working, Trellara stops working.
What it touches
| Question | Answer |
|---|---|
| What is installed in the database? | Nothing. Capture uses pgoutput over the standard replication protocol, so it works on managed PostgreSQL where extensions are not permitted. |
| What does the first command do? | trellara-check is strictly read-only. It creates no publication, no slot, no checkpoint and no target state. |
| Where does data go? | Between your source, your durable log or broker, and your destinations. Nothing is sent to us; there is no hosted component in the open-source path. |
| What runs where? | Ordinary processes in your network — a VPC, a Kubernetes cluster, a back-office server, or a laptop. |
| What does it need a broker for? | Nothing, to start. The local durable log is a disk-backed segment log; Kafka or Redpanda is the scale-out option when you already run one. |
The parts
| Component | Role |
|---|---|
trellara-check | Read-only source diagnostic. Grades slot posture, WAL retention risk and capture readiness. The binary is deliberately tiny so it can be run on a call. |
trellara relay | Decodes pgoutput, assembles committed transactions into envelopes, publishes them durably, then advances the source checkpoint. |
| Durable log | Disk-backed segment log with fsync, offset index, per-consumer cursors, torn-tail detection and large-transaction spill — or Kafka/Redpanda in its place. |
trellara applier | Applies each source transaction atomically at the target. Data, dedup record and checkpoint commit in one target transaction. |
| Proof plane | Watermarks, checksums, snapshot-handoff state, quarantine records, epochs, and an exportable evidence package. |
Whether you need it
One PostgreSQL source, one target, both always online, one team owning the schema? Use native logical replication. It is free, it is in the database, it keeps getting better, and it is one fewer thing to operate.
Trellara starts earning its place when there is more than one database, when nodes go offline, when a stalled consumer would be an incident, or when someone asks whether last night's numbers are complete and the honest answer is that nobody can tell. The next page is the long-form version of that argument, written against us.
Where the name comes from
A trellis is a lattice you build so that something else can grow along it in an order you chose. It carries no fruit of its own, it does not replace the plant, and you notice it only when it is missing — at which point everything it was holding is on the ground.
That is the position Trellara is trying to occupy above PostgreSQL logical replication. The database does the growing. Trellara is the structure that keeps what it produces in order, in one piece, and where you can see it.