PostgreSQL

Detailed information on the PostgreSQL state store component

This component allows using PostgreSQL (Postgres) as state store for Dapr.

Create a Dapr component

Create a file called postgres.yaml, paste the following and replace the <CONNECTION STRING> value with your connection string. The connection string is a standard PostgreSQL connection string. For example, "host=localhost user=postgres password=example port=5432 connect_timeout=10 database=dapr_test". See the PostgreSQL documentation on database connections for information on how to define a connection string.

If you want to also configure PostgreSQL to store actors, add the actorStateStore option as in the example below.

apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
  name: <NAME>
spec:
  type: state.postgresql
  version: v1
  metadata:
  # Connection string
  - name: connectionString
    value: "<CONNECTION STRING>"
  # Timeout for database operations, in seconds (optional)
  #- name: timeoutInSeconds
  #  value: 20
  # Name of the table where to store the state (optional)
  #- name: tableName
  #  value: "state"
  # Name of the table where to store metadata used by Dapr (optional)
  #- name: metadataTableName
  #  value: "dapr_metadata"
  # Cleanup interval in seconds, to remove expired rows (optional)
  #- name: cleanupIntervalInSeconds
  #  value: 3600
  # Max idle time for connections before they're closed (optional)
  #- name: connectionMaxIdleTime
  #  value: 0
  # Uncomment this if you wish to use PostgreSQL as a state store for actors (optional)
  #- name: actorStateStore
  #  value: "true"

Warning

The above example uses secrets as plain strings. It is recommended to use a secret store for the secrets as described here.

Spec metadata fields

Setup PostgreSQL

• Self-Hosted

1. Run an instance of PostgreSQL. You can run a local instance of PostgreSQL in Docker CE with the following command:

   This example does not describe a production configuration because it sets the password in plain text and the user name is left as the PostgreSQL default of “postgres”.

   docker run -p 5432:5432 -e POSTGRES_PASSWORD=example postgres

2. Create a database for state data. Either the default “postgres” database can be used, or create a new database for storing state data.

   To create a new database in PostgreSQL, run the following SQL command:

   CREATE DATABASE dapr_test;

Advanced

TTLs and cleanups

This state store supports Time-To-Live (TTL) for records stored with Dapr. When storing data using Dapr, you can set the ttlInSeconds metadata property to indicate after how many seconds the data should be considered “expired”.

Because PostgreSQL doesn’t have built-in support for TTLs, this is implemented in Dapr by adding a column in the state table indicating when the data is to be considered “expired”. Records that are “expired” are not returned to the caller, even if they’re still physically stored in the database. A background “garbage collector” periodically scans the state table for expired rows and deletes them.

The interval at which the deletion of expired records happens is set with the cleanupIntervalInSeconds metadata property, which defaults to 3600 seconds (that is, 1 hour).

• Longer intervals require less frequent scans for expired rows, but can require storing expired records for longer, potentially requiring more storage space. If you plan to store many records in your state table, with short TTLs, consider setting cleanupIntervalInSeconds to a smaller value, for example 300 (300 seconds, or 5 minutes).
• If you do not plan to use TTLs with Dapr and the PostgreSQL state store, you should consider setting cleanupIntervalInSeconds to a value <= 0 (e.g. 0 or -1) to disable the periodic cleanup and reduce the load on the database.

The column in the state table where the expiration date for records is stored in, expiredate, does not have an index by default, so each periodic cleanup must perform a full-table scan. If you have a table with a very large number of records, and only some of them use a TTL, you may find it useful to create an index on that column. Assuming that your state table name is state (the default), you can use this query:

CREATE INDEX expiredate_idx
    ON state
    USING btree (expiredate ASC NULLS LAST);

Related links

• Basic schema for a Dapr component
• Read this guide for instructions on configuring state store components
• State management building block

Last modified January 3, 2023: Update docs for PostgreSQL state store (#3033) (0d9b5a27)