InfluxDB

Configuration

/etc/influxdb/influxdb.conf

[http]
  auth-enabled = true
Schema Design

official tutorial: InfluxDB schema design

Data Elements

  • timstamp
  • measurement
  • tag key
  • tag value
  • field key
  • field value

Where to store data (tag or field)

tag value

  • 資料型式只能是 string
  • 資料長度不宜過長
  • 資料唯一性的筆數不宜過多

field value

  • 資料型式可以是 strings, floats, integers, or boolean。
    NOTE: 如果是 strings,寫入資料時必須包含雙引號
  • 不支援 GROUP BY 的查詢語法
  • 適合儲存唯一性的資料
  • 一次寫入多筆資料時,每筆的所有 field value 的組合不可有重複,否則會寫入失敗。
  • field 資料不會有 index,如果查詢的語法用到 field,效率會很差。

 

Management

Create a new user and database

influx
> CREATE USER admin WITH PASSWORD 'adminpass' WITH ALL PRIVILEGES
> exit

influx -username admin -password adminpass
> set password for admin = 'newpass'
>
> create database mmap_nmon with duration 180d
> create user mon with password 'thisispassword'
> grant ALL on mmap_nmon to mon
> show GRANTS for mon

Login to InfluxDB

# In the shell
influx -username admin -password thisispass

# In the InfluxDB CLI
> auth
username:
password
InfluxQL
> show databases
name: databases
name
----
_internal
nmon_reports
nmon2influxdb_log

> show users
user  admin
----  -----
admin true
mon   false

> use nmon_reports
Using database nmon_reports
> show measurements
name: measurements
name
----
CPU_ALL
DISKAVGRIO
DISKAVGWIO
DISKBSIZE
DISKBUSY
DISKREAD
DISKREADSERV
DISKRIO
DISKRXFER
DISKSERV
...

Retention Policy

# for current database
> show retention policies
name    duration  shardGroupDuration replicaN default
----    --------  ------------------ -------- -------
autogen 8760h0m0s 168h0m0s           1        true

# for specified database
> show retention policies on nmon2influxdb_log
name          duration shardGroupDuration replicaN default
----          -------- ------------------ -------- -------
autogen       0s       168h0m0s           1        false
log_retention 48h0m0s  24h0m0s            1        true

# Create a policy
> CREATE RETENTION POLICY "one_day_only" ON "NOAA_water_database" DURATION 1d REPLICATION 1

# Alter the policy
> ALTER RETENTION POLICY "what_is_time" ON "NOAA_water_database" DURATION 3w SHARD DURATION 2h DEFAULT

# Delete a policy
> DROP RETENTION POLICY "what_is_time" ON "NOAA_water_database"

Verify the account

curl -G http://localhost:8086/query -u mon:thisispassword --data-urlencode "q=SHOW DATABASES"
{"results":[{"statement_id":0,"series":[{"name":"databases","columns":["name"],"values":[["mmap_nmon"]]}]}]}

查詢表資訊

SHOW MEASUREMENTS  --查詢當前資料庫中含有的表
SHOW FIELD KEYS --查看當前資料庫所有表的欄位
SHOW series from pay --查看key數據
SHOW TAG KEYS FROM "pay" --查看key中tag key值
SHOW TAG VALUES FROM "pay" WITH KEY = "merId" --查看key中tag 指定key值對應的值
SHOW TAG VALUES FROM cpu WITH KEY IN ("region", "host") WHERE service = 'redis'
DROP SERIES FROM  WHERE ='' --刪除key
SHOW CONTINUOUS QUERIES   --查看連續執行命令
SHOW QUERIES  --查看最後執行命令
KILL QUERY  --結束命令
SHOW RETENTION POLICIES ON mydb  --查看保留數據
show series cardinality on mydb --資料庫總筆數

查詢資料

SELECT * FROM /.*/ LIMIT 1  --查詢當前資料庫下所有表的第一行記錄
select * from pay  order by time desc limit 2
select * from  db_name."POLICIES name".measurement_name --指定查詢資料庫下資料保留中的表資料 POLICIES name資料保留

刪除資料

delete from "query" --刪除表所有資料,則表就不存在了
drop MEASUREMENT "query"   --刪除表(注意會把資料保留刪除使用delete不會)
DELETE FROM cpu
DELETE FROM cpu WHERE time < '2000-01-01T00:00:00Z'
DELETE WHERE time < '2000-01-01T00:00:00Z'
DROP DATABASE “testDB” --刪除資料庫
DROP RETENTION POLICY "dbbak" ON mydb --刪除保留資料為dbbak資料
DROP SERIES from pay where tag_key='' --刪除key中的tag

函數使用

  • mean: 平均值
  • sum: 總和
  • min: 最小值
  • max: 最大值
  • count: 總個數
  • difference: 差異數 (前後筆資料的比較)
  • non_negative_difference: 正差異數 (前後筆資料的比較)
select * from pay   order by time desc limit 2
select mean(allTime) from pay where time >= today() group by time(10m) time_zone(+8)
select * from pay time_zone(+8) limit 2
SELECT sum(allTime) FROM "pay" WHERE time > now() - 10s
select count(allTime) from pay  where time > now() - 10m  group by time(1s)

select difference("commit_sql") from "snapdb2" where time > now() - 1h limit 10
select non_negative_difference(*) from "snapdb2" where time > now() - 1h limit 10
select non_negative_difference(/commit_sql|rollback_sql/) from "snapdb2" where time > now() - 1h limit 10

User and Privileges

> CREATE USER "todd" WITH PASSWORD '123456'

> SHOW GRANTS for "todd"

> SET PASSWORD FOR "todd" = 'newpassword'

> GRANT READ ON "NOAA_water_database" TO "todd"
> GRANT ALL ON "NOAA_water_database" TO "todd"

> REVOKE ALL PRIVILEGES FROM "todd"
> REVOKE ALL ON "NOAA_water_database" FROM "todd"
> REVOKE WRITE ON "NOAA_water_database" FROM "todd"

> DROP USER "todd"

Covert timestamp to normal datetime

influx -precision rfc3339
# Or, in CLI
> precision rfc3339

Convert InfluxData to csv format

# With CLI
# There is also useful -precision option to set format of timestamp.
influx -database 'database_name' -execute "SELECT * FROM table_name" -format csv > test.csv

influx -username your_user_if_any -password "secret!" -database 'db_name' -host 'localhost' -execute 'SELECT * FROM "db_name"."your_retention_policy_or_nothing"."your_measurement_name" WHERE time > '\''2017-09-05'\'' and time < '\''2017-09-05T23:59:59Z'\'' AND other_conditions_if_required' -format 'csv' > /tmp/your_measurement_name_20170905.csv

# With HTTP-API
# Samples:
# "q=SELECT * FROM \"mymeasurement\" where time > now() - 130d"
# "q=SELECT * FROM \"mymeasurement\" where (time < now() - 130d) and  (time > now() - 260d)"
curl -G 'http://localhost:8086/query' --data-urlencode "db=mydb" --data-urlencode "epoch=#timeunit" --data-urlencode "q=SELECT * FROM \"mymeasurement\" " -H "Accept: application/csv" >  mytargetcsv.csv

Tag Query

> show tag values from {measurement} with key={key}
> show tag values from {measurement} with key={key} where {tag-key}={tag-value}

 

Services
systemctl start influxdb
systemctl enable influxdb
Learning

 

 


Revision #35
Created Thu, May 20, 2021 5:22 AM by Admin
Updated Wed, Sep 29, 2021 2:19 AM by Admin