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Collectors are modular components in the PostgreSQL Server Exporter that gather specific types of metrics from your PostgreSQL database. Each collector focuses on a particular aspect of database monitoring, such as database size, replication status, or table statistics.

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How Collectors Work

When the exporter scrapes metrics from PostgreSQL:
  1. Each enabled collector queries PostgreSQL system views or functions
  2. The collector transforms the query results into Prometheus metrics
  3. Metrics are exposed at the /metrics endpoint
  4. Collectors run concurrently for efficient data collection
All metrics are prefixed with pg_ by default and include relevant labels for filtering and aggregation.

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Collector States

Each collector can be in one of two states:
  • Enabled by default - The collector runs automatically unless explicitly disabled
  • Disabled by default - The collector must be explicitly enabled to run
You can check the default state of each collector in the documentation pages below.

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Enabling and Disabling Collectors

Collectors are controlled using command-line flags with the format --collector.<name> or --no-collector.<name>.

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Enable a collector

postgres_exporter --collector.stat_statements

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Disable a collector

postgres_exporter --no-collector.database

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Using environment variables

You can also control collectors through environment variables, though command-line flags take precedence: 
export PG_EXPORTER_COLLECTOR_DATABASE=false

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Available Collectors

The following collectors are available in the PostgreSQL Server Exporter:

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Core Database Collectors

  • Database - Database size and connection limits
  • Locks - Lock counts by database and mode
  • Replication - Replication lag and status
  • WAL - Write-Ahead Log segments and size

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Statistics Collectors

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Deprecated Features

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Collector Performance

Each collector execution is tracked with the following metrics:
  • pg_scrape_collector_duration_seconds - Time taken to execute the collector
  • pg_scrape_collector_success - Whether the collector succeeded (1) or failed (0)
These metrics help you monitor the performance and reliability of individual collectors.

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Collection Timeout

You can set a global timeout for all collectors using the --collection.timeout flag: 
postgres_exporter --collection.timeout=30s
When the timeout is reached, the database connection is dropped to prevent connection exhaustion.
The default collection timeout is 1 minute. Set this value based on your database size and query complexity.

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