# QuestDB Wire Protocol (QWP)

Server-side configuration for QWP ingestion and query endpoints.

QWP is QuestDB's columnar binary protocol for high-throughput data ingestion
(`/write/v4`) and streaming query results (`/read/v1`) over WebSocket and UDP.
These properties control protocol limits and the UDP receiver. WebSocket
ingestion and egress share the HTTP server's network settings (port, TLS,
worker threads); see
[HTTP server configuration](/docs/configuration/http-server/) for those.

## Protocol limits

### qwp.max.rows.per.table

- **Default**: `1000000`
- **Reloadable**: no

Maximum number of rows per table block in a single QWP message. The server
rejects batches that exceed this limit with a parse error.

### qwp.max.tables.per.connection

- **Default**: `10000`
- **Reloadable**: no

Maximum number of distinct tables a single connection may write to. The
server rejects messages referencing additional tables once this limit is
reached.

## UDP receiver

:::note

The QWP UDP receiver is a fire-and-forget ingestion path for metrics
workloads where occasional message loss is acceptable. It is disabled by
default. For reliable ingestion, use the WebSocket transport.

:::

### qwp.udp.bind.to

- **Default**: `0.0.0.0:9007`
- **Reloadable**: no

IP address and port the UDP receiver binds to. The default listens on all
network interfaces on port 9007.

### qwp.udp.commit.interval

- **Default**: `2000` (milliseconds)
- **Reloadable**: no

Time interval between commits for data received over UDP. Lower values
reduce the window of uncommitted data at the cost of more frequent I/O.

### qwp.udp.enabled

- **Default**: `false`
- **Reloadable**: no

Enable or disable the QWP UDP receiver.

### qwp.udp.join

- **Default**: `224.1.1.1`
- **Reloadable**: no

Multicast group address the UDP receiver joins. Only relevant when
`qwp.udp.unicast` is `false`.

### qwp.udp.max.uncommitted.datagrams

- **Default**: `1048576`
- **Reloadable**: no

Maximum number of uncommitted datagrams before the receiver forces a commit,
regardless of the time-based commit interval.

### qwp.udp.msg.buffer.size

- **Default**: `65536` (bytes)
- **Reloadable**: no

Size of each message buffer allocated for the UDP receiver.

### qwp.udp.msg.count

- **Default**: `10000`
- **Reloadable**: no

Number of message buffers to pre-allocate. Higher values absorb larger
bursts at the cost of more memory.

### qwp.udp.own.thread

- **Default**: `true`
- **Reloadable**: no

When `true`, the UDP receiver runs in a dedicated thread with a busy-spin
loop for lowest latency. When `false`, the receiver uses the shared worker
pool.

### qwp.udp.own.thread.affinity

- **Default**: `-1` (no affinity)
- **Reloadable**: no

CPU core affinity for the dedicated UDP receiver thread. A value of `-1`
lets the OS schedule the thread. Only applies when `qwp.udp.own.thread` is
`true`.

### qwp.udp.receive.buffer.size

- **Default**: `-1` (OS default)
- **Reloadable**: no

OS-level socket receive buffer size in bytes. A value of `-1` uses the
operating system's default. Increase this if you observe datagram drops
under high throughput.

### qwp.udp.unicast

- **Default**: `true`
- **Reloadable**: no

When `true`, the UDP receiver operates in unicast mode. When `false`, it
joins the multicast group specified by `qwp.udp.join`.