InfluxDB data Retention Policies and influxdbretention

InfluxDB data Retention Policies and influxdbretention

InfluxDB can process thousands of data records per second. To save all the data, it will occupy a lot of storage space. Sometimes we may not need to store all the historical data. Therefore, influxDB introduces a Retention policy to allow us to customize the Retention time of data. For more details about InfluxDB, see the InfluxDB series learning tutorial directory.

InfluxDB technology exchange group: 580487672 (click to join)

I. Description of InfluxDB data retention policies

The Data Retention Policy (RP) of InfluxDB is used to define the time when data is stored in InfluxDB, or to define the data stored during a certain period.

A database can have multiple retention policies, but each policy must be unique.

Ii. InfluxDB data retention policy objective

InfluxDB does not provide data deletion operations. Therefore, the data retention policy is defined to control the data volume.

Therefore, the purpose of defining a data retention policy is to enable InfluxDB to know which data can be discarded to process data more efficiently.

Iii. InfluxDB data retention policy operations

1) query Policy

You can use the following statement to view the existing database policies:

> SHOW RETENTION POLICIES ON telegrafname    duration    shardGroupDuration    replicaN    defaultdefault    0        168h0m0s        1        true

As you can see, telegraf has only one policy. The meaning of each field is as follows:

Name -- name, which is default

Duration-duration, 0 indicates Unlimited

ShardGroupDuration -- the storage time of shardGroup. shardGroup is a basic storage structure of InfluxDB. The query efficiency of data later than this time should be reduced.

ReplicaN -- Full name: REPLICATION, number of replicas

Default -- whether it is the default policy

2) create a policy

> CREATE RETENTION POLICY "2_hours" ON "telegraf" DURATION 2h REPLICATION 1 DEFAULT> SHOW RETENTION POLICIES ON telegrafname    duration    shardGroupDuration    replicaN    defaultdefault    0        168h0m0s        1        false2_hours    2h0m0s        1h0m0s            1        true

The preceding statement can be used to add a policy. In this example, a two-hour policy is added to the telegraf database. The Policy Name Is 2_hours, the duration is 2 hours, the copy is 1, and the Default policy is set.

Because the policy named default is no longer a default policy, you must explicitly add the Policy Name "default" When querying tables using the default policy ".

> select * from "default".cpu limit 2name: cpu---------time            cpu        host                host_id    usage_guest    usage_guest_nice    usage_idle   usage_iowait        usage_irq    usage_nice        usage_softirq    usage_steal    usage_system        usage_user1467884670000000000    cpu-total    ResourcePool-0246-billing07        0        0            99.79994164175388    0            0        0.06251823446523729    0        0        0.12920435125646068    0.0083357646034517271467884670000000000    cpu9        billing07                0        0            97.79338014069532    1.8054162487519367    0        0            0        0        0.10030090272883943    0.3009027081135398

3) modify the policy

Modify the policy using the following statement:

> ALTER RETENTION POLICY "2_hours" ON "telegraf" DURATION 4h DEFAULT> show retention POLICIES on telegrafname    duration    shardGroupDuration    replicaN    defaultdefault    0        168h0m0s        1        false2_hours    4h0m0s        1h0m0s            1        true

We can see that the modified policy has changed.

4) deletion policy

The deletion of policies in InfluxDB is as follows:

> drop retention POLICY "2_hours" ON "telegraf"> show retention POLICIES on telegrafname    duration    shardGroupDuration    replicaN    defaultdefault    0        168h0m0s        1        false

We can see that the policy named 2_hours has been deleted.

IV. Other Instructions

POLICY: the keyword "POLICY" should be in upper case and the keyword "POLICY" should be in lower case.

When a table uses a policy that is not the Default policy, you must explicitly specify the policy name during the operation. Otherwise, an error occurs.

 

Now, we will introduce you to the InfluxDB Retention Policies first. If you have any questions, please leave a message to discuss them.

For more details about InfluxDB, see the InfluxDB series learning tutorial directory.

InfluxDB technology exchange group: 580487672 (click to join)