# Nais Postgres reference > **Experimental feature** > This feature is an alpha feature, and is subject to API change, instability or removal. > See the [main Postgres page](/persistence/postgresql.md) for more information. This document describes all possible configuration values in the `Postgres` spec, commonly known as the `postgres.yaml` file. A `Postgres` is a logical database: pgrator creates its default `main` branch as a separate CNPG cluster. `spec.activeBranch` requests a local branch name; `status.activeBranch` is the observed selection. A requested branch must have an initialized, Ready, non-terminating CNPG cluster before pgrator updates observed status. This check is not an atomic cutover guarantee; verify workload connections when switching branches. ## activeBranch ActiveBranch selects the local branch name within this Postgres for normal workloads. When omitted, pgrator retains the current active branch. Type: `string`
Required: `false`
> **Example** > ```yaml > spec: > activeBranch: main > ``` ## extensions Extensions to enable in the Postgres database. Type: `array`
Required: `false`
> **Example** > ```yaml > spec: > extensions: > - name: postgis > ``` ### extensions[].name Name of the Postgres extension to enable. Type: `string`
Required: `true`
> **Example** > ```yaml > spec: > extensions: > - name: postgis > ``` ## highAvailability HighAvailability adds a third instance and enables synchronous replication. A cluster always runs a primary and a standby, so failover is available either way. What this adds is the guarantee that an acknowledged commit survives losing the primary, at the cost of write latency. Type: `boolean`
Required: `false`
> **Example** > ```yaml > spec: > highAvailability: true > ``` ## majorVersion MajorVersion of Postgres to use. Type: `enum`
Required: `true`
Allowed values: `16`, `17`, `18`
> **Example** > ```yaml > spec: > majorVersion: "18" > ``` ## resources Resources configures compute and disk for the Postgres cluster. Type: `object`
Required: `false`
> **Example** > ```yaml > spec: > resources: > cpu: 100m > diskSize: 10Gi > memory: 512Mi > ``` ### resources.cpu Cpu is the CPU resources for the Postgres cluster. Type: `integer` or `string`
Required: `false`
Pattern: `^(\+|-)?(([0-9]+(\.[0-9]*)?)|(\.[0-9]+))(([KMGTPE]i)|[numkMGTPE]|([eE](\+|-)?(([0-9]+(\.[0-9]*)?)|(\.[0-9]+))))?$`
> **Example** > ```yaml > spec: > resources: > cpu: 100m > ``` ### resources.diskSize DiskSize is the disk size for the Postgres cluster. Type: `integer` or `string`
Required: `false`
Pattern: `^(\+|-)?(([0-9]+(\.[0-9]*)?)|(\.[0-9]+))(([KMGTPE]i)|[numkMGTPE]|([eE](\+|-)?(([0-9]+(\.[0-9]*)?)|(\.[0-9]+))))?$`
> **Example** > ```yaml > spec: > resources: > diskSize: 10Gi > ``` ### resources.memory Memory is the memory resources for the Postgres cluster. Type: `integer` or `string`
Required: `false`
Pattern: `^(\+|-)?(([0-9]+(\.[0-9]*)?)|(\.[0-9]+))(([KMGTPE]i)|[numkMGTPE]|([eE](\+|-)?(([0-9]+(\.[0-9]*)?)|(\.[0-9]+))))?$`
> **Example** > ```yaml > spec: > resources: > memory: 512Mi > ```