InfluxDB Time Series Analysis¶

Software Overview¶

InfluxDB is an open-source distributed time-series and metrics database written in Go.

Industry Position¶

InfluxDB consistently holds the top position, leaving its closest competitor Kdb+ far behind by a margin of three Prometheus distances in the latest time-series database rankings.

Basic Concepts¶

• Database: Database

• Measurement: Data table, analogous to a table in MySQL.

• Field: Key-value pairs that record actual data in InfluxDB (mandatory and not indexed).
• Field Set: A collection of Field key-value pairs.
• Field Key: The key in the Field key-value pair.
• Field Value: The value in the Field key-value pair (the actual data).
• Tag: Key-value pairs used to describe Fields (optional but indexed).
• Tag Set: A collection of Tag key-value pairs.
• Tag Key: The key in the Tag key-value pair.
• Tag Value: The value in the Tag key-value pair.
• Timestamp: The date and time associated with a data point.

Advanced Concepts¶

• Retention Policy: Data storage duration (default is autogen, meaning permanent storage).

• Series: A time series composed of Retention Policy, Measurement, and Tag Set.

• Point: A set of Field Sets with the same Timestamp within a Series, which can also be understood as a row in a table.

• Line Protocol: A text format for writing data points into InfluxDB.

# Convert the above Point to Line Protocol
disk,host=a,path=/ free=40836976,used=20836976 1639238400000000000

Practical Operations¶

1. Software Installation¶

Add the Influxdata yum repository:

cat <<EOF | tee /etc/yum.repos.d/influxdb.repo
[influxdb]
name = InfluxDB Repository - RHEL \$releasever
baseurl = https://repos.influxdata.com/rhel/\$releasever/\$basearch/stable
enabled = 1
gpgcheck = 1
gpgkey = https://repos.influxdata.com/influxdb.key
EOF

yum -y install telegraf influxdb

systemctl start influxdb
systemctl start telegraf

2. Data Query¶

Since it's a local installation, use the influx command to directly enter the database (see more parameters with influx -h):

influx

Select the telegraf database and query data using the select command (query language is InfluxQL):

use telegraf
select * from system limit 3

The image shows 3 Points, each composed of four parts (measurement, timestamp, tag set, field set).

• Measurement

• name = system

• Timestamp

• time = 1637744500000000000 (nanoseconds)

• Tag Set

• host = df-solution-ecs-018

• Field Set

• load = 0, load15 = 0, load5 = 0.01, n_cpus = 4, n_users = 5, uptime = 1106990, uptime_format = 12days,19:29

3. Viewing Time Series¶

Use the show series command to view time series:

show series from cpu

You can see that there are 5 time series for the measurement cpu (cpu-total, cpu0, cpu1, cpu2, cpu3, all with the same host).

4. Time Series Testing¶

4.1 Adding inputs.tags (Plugin Tags)¶

Edit the main configuration file /etc/telegraf/telegraf.conf and add inputs.cpu.tags:

[[inputs.cpu]]
  percpu = true
  totalcpu = true
  collect_cpu_time = false
  report_active = false
[inputs.cpu.tags]
  cloud = 'aliyun'

Restart Telegraf:

systemctl restart telegraf

Use the show series command to view time series:

show series from cpu

You can see that the number of time series for the measurement cpu has increased from 5 to 10.

4.2 Deleting a Measurement¶

Use the drop command to delete a measurement:

drop measurement cpu

Use the show series command again to view time series:

show series from cpu

You can see that the number of time series for the measurement cpu has returned to 5 (cpu-total, cpu0, cpu1, cpu2, cpu3, with the same host/cloud).

4.3 Adding global_tags (Global Tags)¶

Edit the main configuration file /etc/telegraf/telegraf.conf and add global_tags:

[global_tags]
  user = 'admin'

Restart Telegraf:

systemctl restart telegraf

Use the show series command to view time series:

show series from cpu

You can see that the number of time series for the measurement cpu has increased from 5 to 10 again.

Use the show series command to view time series for other measurements:

show series from mem

You can see that the number of time series for the measurement mem has increased from 1 to 2.

Simple Analysis¶

• Retention Policy
• Using plugin tags will double the number of time series for that measurement.
• Using global tags will double the number of time series for that database.

• If the measurement remains unchanged, the more combinations of tags, the more time series.

• Measurement

• Once deleted, all time series under that measurement will be cleared.

• Tag

• Typically enumerable, such as hostname, status.
• Should not be random numbers; otherwise, it can lead to a large number of time series, such as container IDs, source IPs.