InfluxDB Line Protocol Overview

QuestDB implements the InfluxDB Line Protocol to ingest data.

The InfluxDB Line Protocol is for data ingestion only.

For building queries, see the Query & SQL Overview.

Each ILP client library also has its own language-specific documentation set.

This supporting document thus provides an overview to aid in client selection and initial configuration:

  1. Client libraries
  2. Configuration
  3. Authentication
  4. Transactionality caveat

Client libraries​

The quickest way to get started is to select your library of choice.

From there, its documentation will carry you through to implementation.

Client libraries are available for several languages:

If you'd like more context on ILP overall, please continue reading.

Enable or disable ILP​

If going over HTTP, ILP will use shared HTTP port 9000 (default) if the following is set in server.conf:

line.http.enabled=true

Configuration​

The HTTP receiver configuration can be completely customized using QuestDB configuration keys for ILP.

Configure the thread pools, buffer and queue sizes, receiver IP address and port, load balancing, and more.

For more guidance in how to tune QuestDB, see capacity planning.

Authentication​

note

Using QuestDB Enterprise?

Skip to advanced security features instead, which provides holistic security out-of-the-box.

InfluxDB Line Protocol supports authentication.

A similar pattern is used across all client libraries.

This document will break down and demonstrate the configuration keys and core configuration options.

Once a client has been selected and configured, resume from your language client documentation.

Configuration strings​

Configuration strings combine a set of key/value pairs.

Assembling a string connects an ILP client to a QuestDB ILP server.

The standard configuration string pattern is:


schema::key1=value1;key2=value2;key3=value3;

It is made up of the following parts:

  • Schema: One of the specified schemas in the base values section below
  • Key=Value: Each key-value pair sets a specific parameter for the client
  • Terminating semicolon: A semicolon must follow the last key-value pair

Client parameters​

Below is a list of common parameters that ILP clients will accept.

These params facilitate connection to QuestDB's ILP server and define client-specific behaviors.

Some are shared across all clients, while some are client specific.

See the Usage section for write examples that use these schemas.

warning

Any parameters tagged as SENSITIVE must be handled with care.

Exposing these values may expose your database to bad actors.

Core parameters​

  • schema: Specifies the transport method, with support for: http, https, tcp & tcps
  • addr: The address and port of the QuestDB server.

HTTP Parameters​

  • username: Username for HTTP authentication.
  • password (SENSITIVE): Password for HTTP Basic authentication.
  • token (SENSITIVE): Bearer token for HTTP Token authentication.
    • Open source HTTP users are unable to generate tokens. For TCP token auth, see the below section.
  • request_min_throughput: Expected throughput for network send to the database server, in bytes.
    • Defaults to 100 KiB/s
    • Used to calculate a dynamic timeout for the request, so that larger requests do not prematurely timeout.
  • request_timeout: Base timeout for HTTP requests to the database, in milliseconds.
    • Defaults to 10 seconds.
  • retry_timeout: Maximum allowed time for client to attempt retries, in milliseconds.
    • Defaults to 10 seconds.
    • Not all errors are retriable.

TCP Parameters​

  • username: Username for TCP authentication.
  • token (SENSITIVE): TCP Authentication d parameter.
    • token_x (SENSITIVE): TCP Authentication x parameter.
      • Used in C/C++/Rust/Python clients.
    • token_y (SENSITIVE): TCP Authentication y parameter.
      • Used in C/C++/Rust/Python clients.
  • auth_timeout: Timeout for TCP authentication with QuestDB server, in milliseconds.
    • Default 15 seconds.
TCP token authentication setup​

Create d, x & y tokens for client usage.

Prerequisites​
  • jose: C-language implementation of Javascript Object Signing and Encryption. Generates tokens.
  • jq: For pretty JSON output.
brew install jose
brew install jq
Server configuration​

Next, create an authentication file.

Only elliptic curve (P-256) are supported (key type ec-p-256-sha256):

testUser1 ec-p-256-sha256 fLKYEaoEb9lrn3nkwLDA-M_xnuFOdSt9y0Z7_vWSHLU Dt5tbS1dEDMSYfym3fgMv0B99szno-dFc1rYF9t0aac
# [key/user id] [key type] {keyX keyY}

Generate an authentication file using the jose utility:

jose jwk gen -i '{"alg":"ES256", "kid": "testUser1"}' -o /var/lib/questdb/conf/full_auth.json

KID=$(cat /var/lib/questdb/conf/full_auth.json | jq -r '.kid')
X=$(cat /var/lib/questdb/conf/full_auth.json | jq -r '.x')
Y=$(cat /var/lib/questdb/conf/full_auth.json | jq -r '.y')

echo "$KID ec-p-256-sha256 $X $Y" | tee /var/lib/questdb/conf/auth.txt

Once created, reference it in the server configuration:

/path/to/server.conf
line.tcp.auth.db.path=conf/auth.txt
Client keys​

For the server configuration above, the corresponding JSON Web Key must be stored on the clients' side.

When sending a fully-composed JWK, it will have the following keys:

{
  "kty": "EC",
  "d": "5UjEMuA0Pj5pjK8a-fa24dyIf-Es5mYny3oE_Wmus48",
  "crv": "P-256",
  "kid": "testUser1",
  "x": "fLKYEaoEb9lrn3nkwLDA-M_xnuFOdSt9y0Z7_vWSHLU",
  "y": "Dt5tbS1dEDMSYfym3fgMv0B99szno-dFc1rYF9t0aac"
}

The d, x and y parameters generate the public key.

For example, the Python client would be configured as outlined in the Python docs.

Auto-flushing behavior​

  • auto_flush: Enable or disable automatic flushing (on/off).

    • Default is “on” for clients that support auto-flushing (all except C, C++ & Rust).

  • auto_flush_rows: Auto-flushing is triggered above this row count.

    • Defaults to 75,000 for HTTP, and 600 for TCP.
    • If set, this implies “auto_flush=on”.

  • auto_flush_interval: Auto-flushing is triggered after this time period has elapsed since the last flush, in milliseconds.

    • Defaults to 1 second
    • This is not a periodic timer - it will only be checked on the next row creation.

  • auto_flush_bytes Auto-flushing is triggered above this buffer size.

    • Disabled by default.

Network configuration​

Optional.

  • bind_interface: Specify the local network interface for outbound connections.
    • Not to be confused with the QuestDB port in the addr param.

TLS configuration​

  • tls_verify: Toggle verification of TLS certificates. Default is on.
  • tls_roots: Specify the source of bundled TLS certificates.
    • The defaults and possible param values are client-specific.
      • In Rust and Python this might be “webpki”, “os-certs” or a path to a “pem” file.
      • In Java this might be a path to a “jks” trust store.
      • tls_roots_password Password to a configured tls_roots if any.
        • Passwords are sensitive! Manage appropriately.
  • tls_ca: Path to single certificate authourity, not supported on all clients.
    • Java for instance would apply tls_roots=/path/to/Java/key/store

Buffer configuration​

  • init_buf_size: Set the initial (but growable) size of the buffer in bytes.
    • Defaults to 64 KiB.
  • max_buf_size: Sets the growth limit of the buffer in bytes.
    • Defaults to 100 MiB.
    • Clients will error if this is exceeded.
  • max_name_len: The maximum alloable number of UTF-8 bytes in the table or column names.
    • Defaults to 127.
    • Related to length limits for filenames on the user's host OS.

Transactionality caveat​

As of writing, the HTTP endpoint does not provide full transactionality in all cases.

Specifically:

  • If an HTTP request contains data for two tables and the final commit fails for the second table, the data for the first table will still be committed. This is a deviation from full transactionality, where a failure in any part of the transaction would result in the entire transaction being rolled back.

  • When adding new columns to a table, an implicit commit occurs each time a new column is added. If the request is aborted or has parse errors, this commit cannot be rolled back.