Create a Last Value Cache

Use the influxdb3 create last_cache command to create a Last Value Cache (LVC). Provide the following:

• Database (-d, --database): (Required) The name of the database to associate the LVC with. You can also use the INFLUXDB3_DATABASE_NAME environment variable to specify the database.
• Token (--token): (Required) Your InfluxDB 3 Core

authentication token. You can also use the INFLUXDB3_AUTH_TOKEN environment variable to specify the token.

• Table (-t, --table): (Required) The name of the table to associate the LVC with.

• Key columns (--key-columns): Specify which columns to include in the primary key of the cache. Rows in the LVC are uniquely identified by their timestamp and key columns, so include all the columns you need to identify each row. These are typically tags, but you can use any columns with the following types:

  • String
  • Integer
  • Unsigned integer
  • Boolean

• Value columns (--value-columns): Specify which columns to cache as value columns. These are typically fields but can also be tags. By default, time and columns other than those specified as --key-columns are cached as value columns.

• Count (--count): The number of values to cache per unique key column combination. The supported range is [1-10]. The default count is 1.

• Time-to-Live (TTL) (--ttl): The time-to-live for cached values in humantime form. The default TTL is four hours.

• Cache name: A unique name for the cache. If you don’t provide one, InfluxDB automatically generates a cache name for you.

influxdb3 create last_cache \
  --database 
DATABASE_NAME
 \
  --token 
AUTH_TOKEN
 \
  --table 
TABLE_NAME
 \
  --key-columns 
KEY_COLUMNS
 \
  --value-columns 
VALUE_COLUMNS
 \
  --count 
COUNT
 \
  --ttl 
TTL
\
  
LVC_NAME

Use the HTTP API

To use the HTTP API to create a Last Value Cache, send a POST request to the /api/v3/configure/last_cache endpoint.

POST /api/v3/configure/last_cache

curl -X POST "https://localhost:8181/api/v3/configure/last_cache" \
  --header "Authorization: Bearer 
AUTH_TOKEN
" \
  --json '{
    "db": "
DATABASE_NAME
",
    "table": "
TABLE_NAME
",
    "name": "
LVC_NAME
",
    "key_columns": ["
KEY_COLUMNS
"],
    "value_columns": ["
VALUE_COLUMNS
"],
    "count": 
COUNT
,
    "ttl": 
TTL
  }'

Example

 curl -X POST "https://localhost:8181/api/v3/configure/last_cache" \
  --header "Authorization: Bearer 00xoXX0xXXx0000XxxxXx0Xx0xx0" \
  --json '{
    "db": "example-db",
    "table": "home",
    "name": "homeLastCache",
    "key_columns": ["room", "wall"],
    "value_columns": ["temp", "hum", "co"],
    "count": 5,
    "ttl": 14400
  }'

Response codes:

• 201 : Success. Last cache created.
• 400 : Bad request.
• 401 : Unauthorized.
• 404 : Cache not found.
• 409 : Cache already exists.

Replace the following:

• DATABASE_NAME: the name of the database to associate the LVC with

• AUTH_TOKEN: your InfluxDB 3 Core

  authentication token

• TABLE_NAME: the name of the table to associate the LVC with

• KEY_COLUMNS: a comma-delimited list of columns to use to unique identify each series–for example: room,wall

• VALUE_COLUMNS: a comma-delimited list of columns to cache as value columns–for example: temp,hum,co

• COUNT: the number of last values to cache per series–for example: 5

• TTL: the TTL of cached values in humantime form–for example: 10s, 1min 30sec, 3 hours

• LVC_NAME: a unique name for the LVC

The cache imports the distinct values from the table and starts caching them.