ILP Overview

QuestDB implements the InfluxDB line protocol to ingest data. QuestDB can listen for line protocol packets over TCP.

This page aims to provide examples for QuestDB experts setting up TCP without any client libraries, or those looking to implement a new client library yourself.

tip

For general QuestDB users, client libraries are available for a number of languages: ILP client libraries.

Examples#

We provide examples in a number of programming languages. See our ILP section of the "develop" docs.

Usage#

Syntax#

table_name,symbolset columnset timestamp\n

Element	Definition
`table_name`	Name of the table where QuestDB will write data.
`symbolset`	A set of comma-separated `name=value` pairs that will be parsed as symbol columns.
`columnset`	A set of comma-separated `name=value` pairs that will be parsed as non-symbol columns.
`timestamp`	UNIX timestamp. The default unit is nanosecond and is configurable via `line.tcp.timestamp`. The value will be truncated to microsecond resolution when parsed by QuestDB.

name in the name=value pair always corresponds to column name in the table.

note

Each ILP message has to end with a new line \n character.

Behavior#

When the table_name does not correspond to an existing table, QuestDB will create the table on the fly using the name provided. Column types will be automatically recognized and assigned based on the data.
The timestamp column is automatically created as designated timestamp with the partition strategy set to DAY. Alternatively, use CREATE TABLE to create the table with a different partition strategy before ingestion.
When the timestamp is empty, QuestDB will use the server timestamp.

Difference from InfluxDB#

QuestDB TCP Receiver uses ILP as both serialization and the transport format. InfluxDB on other hand uses HTTP as the transport and ILP as serialization format. For this reason the existing InfluxDB client libraries will not work with QuestDB.

Generic example#

Let's assume the following data:

timestamp	city	temperature	humidity	make
1465839830100400000	London	23.5	0.343	Omron
1465839830100600000	Bristol	23.2	0.443	Honeywell
1465839830100700000	London	23.6	0.358	Omron

The line protocol syntax for that table is:

readings,city=London,make=Omron temperature=23.5,humidity=0.343 1465839830100400000\n
readings,city=Bristol,make=Honeywell temperature=23.2,humidity=0.443 1465839830100600000\n
readings,city=London,make=Omron temperature=23.6,humidity=0.348 1465839830100700000\n

This would create table similar to this SQL statement and populate it.

CREATE TABLE readings (
  timestamp TIMESTAMP,
  city SYMBOL,
  temperature DOUBLE,
  humidity DOUBLE,
  make SYMBOL
) TIMESTAMP(timestamp) PARTITION BY DAY;

Irregularly-structured data#

InfluxDB line protocol makes it possible to send data under different shapes. Each new entry may contain certain tags or fields, and others not. QuestDB supports on-the-fly data structure changes with minimal overhead. Whilst the example just above highlights structured data, it is possible for InfluxDB line protocol users to send data as follows:

readings,city=London temperature=23.2 1465839830100400000\n
readings,city=London temperature=23.6 1465839830100700000\n
readings,make=Honeywell temperature=23.2,humidity=0.443 1465839830100800000\n

This would result in the following table:

timestamp	city	temperature	humidity	make
1465839830100400000	London	23.5	NULL	NULL
1465839830100700000	London	23.6	NULL	NULL
1465839830100800000	NULL	23.2	0.358	Honeywell

tip

Whilst we offer this function for flexibility, we recommend that users try to minimise structural changes to maintain operational simplicity.

Duplicate column names#

If line contains duplicate column names, the value stored in the table will be that from the first name=value pair on each line. For example:

trade,ticker=USD price=30,price=60 1638202821000000000\n

Price 30 is stored, 60 is ignored.

Name restrictions#

Both table name and column names are allowed to have spaces . These spaces have to be escaped with \. For example both of these are valid lines.

trade\ table,ticker=USD price=30,details="Latest price" 1638202821000000000\n

trade,symbol\ ticker=USD price=30,details="Latest price" 1638202821000000000\n

Table and column names must not contain any of the forbidden characters: \n,\r,?,,,:,",',\,/,\0,),(,+,*,~ and %.

Additionally, table name must not start or end with the . character. Column name must not contain . and -.

Symbolset#

Area of the message that contains comma-separated set of name=value pairs for symbol columns. For example in a message like this:

trade,ticker=BTCUSD,venue=coinbase price=30,price=60 1638202821000000000\n

symbolset is ticker=BTCUSD,venue=coinbase. Please note the mandatory space between symbolset and columnset. Naming rules for columns are subject to duplicate rules and name restrictions.

Symbolset values#

symbolset values are always interpreted as SYMBOL. Parser takes values literally so please beware of accidentally using high cardinality types such as 9092i or 1.245667. This will result in a significant performance loss due to large mapping tables.

symbolset values are not quoted. They are allowed to have special characters, such as (space), =, ,, \n, \r and \, which must be escaped with a \. Example:

trade,ticker=BTC\\USD\,All,venue=coin\ base price=30 1638202821000000000\n

Whenever symbolset column does not exist, it will be added on-the-fly with type SYMBOL. On other hand when the column does exist, it is expected to be of SYMBOL type, otherwise the line is rejected.

Columnset#

Area of the message that contains comma-separated set of name=value pairs for non-symbol columns. For example in a message like this:

trade,ticker=BTCUSD priceLow=30,priceHigh=60 1638202821000000000\n

columnset is priceLow=30,priceHigh=60. Naming rules for columns are subject to duplicate rules and name restrictions.

Columnset values#

columnset supports several values types, which are used to either derive type of new column or mapping strategy when column already exists. These types are limited by existing Influx Line Protocol specification. Wider QuestDB type system is available by creating table via SQL upfront. The following are supported value types: Integer, Long256, Float, String and Timestamp

Designated timestamp#

Designated timestamp is the trailing value of an ILP message. It is optional, and when present, is a timestamp in Epoch nanoseconds. When the timestamp is omitted, the server will insert each message using the system clock as the row timestamp.

warning

While columnset timestamp type units are microseconds, the designated timestamp units are nanoseconds. These are default units, which can be overridden via the line.tcp.timestamp configuration property.

Example of ILP message with desginated timestamp value

tracking,loc=north val=200i 1000000000\n

Example of ILP message sans timestamp

tracking,loc=north val=200i\n

note

We recommend populating designated timestamp via trailing value syntax above.

It is also possible to populate designated timestamp via columnset. Please see mixed timestamp reference.