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Last Cache

content/shared/influxdb3-cli/create/last_cache.md

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The influxdb3 create last_cache command creates a last value cache, which stores the most recent values for specified columns in a table. Use this to efficiently retrieve the latest values based on key column combinations.

Usage

{{% code-placeholders "DATABASE_NAME|TABLE_NAME|AUTH_TOKEN|CACHE_NAME" %}}

<!--pytest.mark.skip-->
bash
influxdb3 create last_cache [OPTIONS] \
  --database DATABASE_NAME \
  --table TABLE_NAME \
  --token AUTH_TOKEN \
  CACHE_NAME

{{% /code-placeholders %}}

Arguments

  • CACHE_NAME: (Optional) Name for the cache. If omitted, InfluxDB automatically generates one.

Options

OptionDescription
-H--hostHost URL of the running {{< product-name >}} server (default is http://127.0.0.1:8181)
-d--database({{< req >}}) Name of the database to operate on
--token({{< req >}}) Authentication token
-t--table({{< req >}}) Table to create the cache for
--key-columnsComma-separated list of columns to use as keys in the cache--for example: foo,bar,baz
--value-columnsComma-separated list of columns to store as values in the cache--for example: foo,bar,baz
--countNumber of entries per unique key column combination to store in the cache
--ttlCache entries' time-to-live (TTL) in Humantime form--for example: 10s, 1min 30sec, 3 hours
--tls-caPath to a custom TLS certificate authority (for testing or self-signed certificates)
--tls-no-verifyDisable TLS certificate verification. Not recommended in production. Useful for testing with self-signed certificates
-h--helpPrint help information
--help-allPrint detailed help information

Option environment variables

You can use the following environment variables as substitutes for CLI options:

Environment VariableOption
INFLUXDB3_HOST_URL--host
INFLUXDB3_DATABASE_NAME--database
INFLUXDB3_AUTH_TOKEN--token
INFLUXDB3_TLS_NO_VERIFY--tls-no-verify

Prerequisites

Before creating a last value cache, ensure you’ve done the following:

  • Create a database.
  • Create a table with the columns you want to cache.
  • Have a valid authentication token.

Examples

A last value cache stores the most recent values from specified columns in a table.

Create a basic last value cache for one column

The following example shows how to track the most recent value for a single key (the last temperature for each room):

<!--pytest.mark.skip-->
bash
influxdb3 create last_cache \
  --database DATABASE_NAME \
  --table my_sensor_table \
  --token AUTH_TOKEN \
  --key-columns room \
  --value-columns temp \
  my_temp_cache

Create a last value cache with multiple keys and values

The following example shows how to:

  • Use multiple columns as a composite key
  • Track several values per key combination
  • Set a cache entry limit with --count
  • Configure automatic expiry with --ttl
<!--pytest.mark.skip-->
bash
influxdb3 create last_cache \
  --database DATABASE_NAME \
  --table my_sensor_table \
  --token AUTH_TOKEN \
  --key-columns room,sensor_id \
  --value-columns temp,hum \
  --count 10 \
  --ttl 1h \
  my_sensor_cache

Usage notes

  • Define the table schema to include all specified key and value columns.
  • Pass tokens using --token, unless you've set one through an environment variable.
  • Specify --count and --ttl to override the defaults; otherwise, the system uses default values.