Getting started with InfluxDB OSS

With InfluxDB open source (OSS) installed, you’re ready to start doing some awesome things.In this section we’ll use the influx command line interface (CLI), which is included in allInfluxDB packages and is a lightweight and simple way to interact with the database.The CLI communicates with InfluxDB directly by making requests to the InfluxDB API over port 8086 by default.

Note: The database can also be used by making raw HTTP requests.See Writing Data and Querying Datafor examples with the curl application.

Creating a database

If you’ve installed InfluxDB locally, the influx command is available via the command line.Execute influx to start the CLI and automatically connect to the local InfluxDB instance(assuming you have already started the server with service influxdb start or by running influxd directly).The output should look like this:

  1. $ influx -precision rfc3339
  2. Connected to http://localhost:8086 version 1.7.x
  3. InfluxDB shell 1.7.x
  4. >

Notes:

  • The InfluxDB API runs on port 8086 by default.Therefore, influx will connect to port 8086 and localhost by default.If you need to alter these defaults, run influx —help.
  • The -precision argument specifies the format/precision of any returned timestamps.In the example above, rfc3339 tells InfluxDB to return timestamps in RFC3339 format (YYYY-MM-DDTHH:MM:SS.nnnnnnnnnZ).

The command line is now ready to take input in the form of the Influx Query Language (a.k.a InfluxQL) statements.To exit the InfluxQL shell, type exit and hit return.

A fresh install of InfluxDB has no databases (apart from the system internal),so creating one is our first task.You can create a database with the CREATE DATABASE <db-name> InfluxQL statement,where <db-name> is the name of the database you wish to create.Names of databases can contain any unicode character as long as the string is double-quoted.Names can also be left unquoted if they contain _only ASCII letters,digits, or underscores and do not begin with a digit.

Throughout this guide, we’ll use the database name mydb:

  1. > CREATE DATABASE mydb
  2. >

Notes:

  • default is a reserved InfluxQL keyword and cannot be used as a database name.
  • After hitting enter, a new prompt appears and nothing else is displayed.In the CLI, this means the statement was executed and there were no errors to display.If something goes wrong, an error is displayed. No news is good news!

Now that the mydb database is created, we’ll use the SHOW DATABASES statementto display all existing databases:

  1. > SHOW DATABASES
  2. name: databases
  3. name
  4. ----
  5. _internal
  6. mydb
  8. >

Note: The _internal database is created and used by InfluxDB to store internal runtime metrics.Check it out later to get an interesting look at how InfluxDB is performing under the hood.

Unlike SHOW DATABASES, most InfluxQL statements must operate against a specific database.You may explicitly name the database with each query,but the CLI provides a convenience statement, USE <db-name>,which will automatically set the database for all future requests. For example:

  1. > USE mydb
  2. Using database mydb
  3. >

Now future commands will only be run against the mydb database.

Writing and exploring data

Now that we have a database, InfluxDB is ready to accept queries and writes.

First, a short primer on the datastore.Data in InfluxDB is organized by “time series”,which contain a measured value, like “cpu_load” or “temperature”.Time series have zero to many points, one for each discrete sample of the metric.Points consist of time (a timestamp), a measurement (“cpu_load”, for example),at least one key-value field (the measured value itself, e.g.“value=0.64”, or “temperature=21.2”), and zero to many key-value tags containing any metadata about the value (e.g.“host=server01”, “region=EMEA”, “dc=Frankfurt”).

Conceptually you can think of a measurement as an SQL table,where the primary index is always time.tags and fields are effectively columns in the table.tags are indexed, and fields are not.The difference is that, with InfluxDB, you can have millions of measurements,you don’t have to define schemas up-front, and null values aren’t stored.

Points are written to InfluxDB using the InfluxDB line protocol, which follows the following format:

  1. <measurement>[,<tag-key>=<tag-value>...] <field-key>=<field-value>[,<field2-key>=<field2-value>...] [unix-nano-timestamp]

The following lines are all examples of points that can be written to InfluxDB:

  1. cpu,host=serverA,region=us_west value=0.64
  2. payment,device=mobile,product=Notepad,method=credit billed=33,licenses=3i 1434067467100293230
  3. stock,symbol=AAPL bid=127.46,ask=127.48
  4. temperature,machine=unit42,type=assembly external=25,internal=37 1434067467000000000

Note: For details on the InfluxDB line protocol, see InfluxDB line protocol syntax page.

To insert a single time series data point into InfluxDB using the CLI, enter INSERT followed by a point:

  1. > INSERT cpu,host=serverA,region=us_west value=0.64
  2. >

A point with the measurement name of cpu and tags host and region has now been written to the database, with the measured value of 0.64.

Now we will query for the data we just wrote:

  1. > SELECT "host", "region", "value" FROM "cpu"
  2. name: cpu
  3. ---------
  4. time                                     host         region   value
  5. 2015-10-21T19:28:07.580664347Z  serverA      us_west     0.64
  7. >

Note: We did not supply a timestamp when writing our point.When no timestamp is supplied for a point, InfluxDB assigns the local current timestamp when the point is ingested.That means your timestamp will be different.

Let’s try storing another type of data, with two fields in the same measurement:

  1. > INSERT temperature,machine=unit42,type=assembly external=25,internal=37
  2. >

To return all fields and tags with a query, you can use the * operator:

  1. > SELECT * FROM "temperature"
  2. name: temperature
  3. -----------------
  4. time                                     external      internal     machine    type
  5. 2015-10-21T19:28:08.385013942Z  25                37             unit42  assembly
  7. >

Warning: Using * without a LIMIT clause on a large database can cause performance issues.You can use Ctrl+C to cancel a query that is taking too long to respond.

InfluxQL has many features and keywords that are not covered here,including support for Go-style regex. For example:

  1. > SELECT  FROM /./ LIMIT 1

> SELECT * FROM "cpu" WHERE "value" > 0.9

This is all you need to know to write data into InfluxDB and query it back.To learn more about the InfluxDB write protocol,check out the guide on Writing Data.To further explore the query language,check out the guide on Querying Data.For more information on InfluxDB concepts, check out the Key Concepts page.