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# Prometheus Collector for PGX Pool

This is a [Prometheus Collector](https://pkg.go.dev/github.com/prometheus/client_golang/prometheus#Collector) for [PGX Pool](https://pkg.go.dev/github.com/jackc/pgx/v5/pgxpool).

## Example Usage

```go
package main

import (
	"context"
	"log"
	"net/http"
	"os"

	"github.com/jackc/pgx/v5/pgxpool"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"

	"github.com/IBM/pgxpoolprometheus"
)

func main() {
	pool, err := pgxpool.Connect(context.Background(), os.Getenv("DATABASE_URL"))
	if err != nil {
		log.Fatal(err)
	}

	collector := pgxpoolprometheus.NewCollector(pool, map[string]string{"db_name": "my_db"})
	prometheus.MustRegister(collector)

	http.Handle("/metrics", promhttp.Handler())
	log.Fatal(http.ListenAndServe(":8080", nil))
}
```

## Metrics Collected

This collector provides metrics for all the stats produced by [pgxpool.Stat](https://pkg.go.dev/github.com/jackc/pgx/v5/pgxpool#Stat) all prefixed with `pgxpool`:

| Name                               | Description                                                                                                                                |
|------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------|
| pgxpool_acquire_count              | Cumulative count of successful acquires from the pool.                                                                                     |
| pgxpool_acquire_duration_ns        | Total duration of all successful acquires from the pool in nanoseconds.                                                                    |
| pgxpool_acquired_conns             | Number of currently acquired connections in the pool.                                                                                      |
| pgxpool_canceled_acquire_count     | Cumulative count of acquires from the pool that were canceled by a context.                                                                |
| pgxpool_constructing_conns         | Number of conns with construction in progress in the pool.                                                                                 |
| pgxpool_empty_acquire              | Cumulative count of successful acquires from the pool that waited for a resource to be released or constructed because the pool was empty. |
| pgxpool_empty_acquire_wait_time_ns | Cumulative time waited for successful acquires from the pool for a resource to be released or constructed because the pool was empty.      | 
| pgxpool_idle_conns                 | Number of currently idle conns in the pool.                                                                                                |
| pgxpool_max_conns                  | Maximum size of the pool.                                                                                                                  |
| pgxpool_max_idle_destroy_count     | Cumulative count of connections destroyed because they exceeded MaxConnIdleTime.                                                           |
| pgxpool_max_lifetime_destroy_count | Cumulative count of connections destroyed because they exceeded MaxConnLifetime.                                                           |
| pgxpool_new_conns_count            | Cumulative count of new connections opened.                                                                                                | 
| pgxpool_total_conns                | Total number of resources currently in the pool. The value is the sum of ConstructingConns, AcquiredConns, and IdleConns.                  |