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# PostgreSQL


<img src="https://netdata.cloud/img/postgres.svg" width="150"/>


Plugin: go.d.plugin
Module: postgres

<img src="https://img.shields.io/badge/maintained%20by-Netdata-%2300ab44" />

## Overview

This collector monitors the activity and performance of Postgres servers, collects replication statistics, metrics for each database, table and index, and more.


It establishes a connection to the Postgres instance via a TCP or UNIX socket.
To collect metrics for database tables and indexes, it establishes an additional connection for each discovered database.


This collector is supported on all platforms.

This collector supports collecting metrics from multiple instances of this integration, including remote instances.


### Default Behavior

#### Auto-Detection

By default, it detects instances running on localhost by trying to connect as root and netdata using known PostgreSQL TCP and UNIX sockets:

- 127.0.0.1:5432
- /var/run/postgresql/


#### Limits

Table and index metrics are not collected for databases with more than 50 tables or 250 indexes.
These limits can be changed in the configuration file.


#### Performance Impact

The default configuration for this integration is not expected to impose a significant performance impact on the system.


## Metrics

Metrics grouped by *scope*.

The scope defines the instance that the metric belongs to. An instance is uniquely identified by a set of labels.



### Per PostgreSQL instance

These metrics refer to the entire monitored application.

This scope has no labels.

Metrics:

| Metric | Dimensions | Unit |
|:------|:----------|:----|
| postgres.connections_utilization | used | percentage |
| postgres.connections_usage | available, used | connections |
| postgres.connections_state_count | active, idle, idle_in_transaction, idle_in_transaction_aborted, disabled | connections |
| postgres.transactions_duration | a dimension per bucket | transactions/s |
| postgres.queries_duration | a dimension per bucket | queries/s |
| postgres.locks_utilization | used | percentage |
| postgres.checkpoints_rate | scheduled, requested | checkpoints/s |
| postgres.checkpoints_time | write, sync | milliseconds |
| postgres.bgwriter_halts_rate | maxwritten | events/s |
| postgres.buffers_io_rate | checkpoint, backend, bgwriter | B/s |
| postgres.buffers_backend_fsync_rate | fsync | calls/s |
| postgres.buffers_allocated_rate | allocated | B/s |
| postgres.wal_io_rate | write | B/s |
| postgres.wal_files_count | written, recycled | files |
| postgres.wal_archiving_files_count | ready, done | files/s |
| postgres.autovacuum_workers_count | analyze, vacuum_analyze, vacuum, vacuum_freeze, brin_summarize | workers |
| postgres.txid_exhaustion_towards_autovacuum_perc | emergency_autovacuum | percentage |
| postgres.txid_exhaustion_perc | txid_exhaustion | percentage |
| postgres.txid_exhaustion_oldest_txid_num | xid | xid |
| postgres.catalog_relations_count | ordinary_table, index, sequence, toast_table, view, materialized_view, composite_type, foreign_table, partitioned_table, partitioned_index | relations |
| postgres.catalog_relations_size | ordinary_table, index, sequence, toast_table, view, materialized_view, composite_type, foreign_table, partitioned_table, partitioned_index | B |
| postgres.uptime | uptime | seconds |
| postgres.databases_count | databases | databases |

### Per repl application

These metrics refer to the replication application.

Labels:

| Label      | Description     |
|:-----------|:----------------|
| application | application name |

Metrics:

| Metric | Dimensions | Unit |
|:------|:----------|:----|
| postgres.replication_app_wal_lag_size | sent_lag, write_lag, flush_lag, replay_lag | B |
| postgres.replication_app_wal_lag_time | write_lag, flush_lag, replay_lag | seconds |

### Per repl slot

These metrics refer to the replication slot.

Labels:

| Label      | Description     |
|:-----------|:----------------|
| slot | replication slot name |

Metrics:

| Metric | Dimensions | Unit |
|:------|:----------|:----|
| postgres.replication_slot_files_count | wal_keep, pg_replslot_files | files |

### Per database

These metrics refer to the database.

Labels:

| Label      | Description     |
|:-----------|:----------------|
| database | database name |

Metrics:

| Metric | Dimensions | Unit |
|:------|:----------|:----|
| postgres.db_transactions_ratio | committed, rollback | percentage |
| postgres.db_transactions_rate | committed, rollback | transactions/s |
| postgres.db_connections_utilization | used | percentage |
| postgres.db_connections_count | connections | connections |
| postgres.db_cache_io_ratio | miss | percentage |
| postgres.db_io_rate | memory, disk | B/s |
| postgres.db_ops_fetched_rows_ratio | fetched | percentage |
| postgres.db_ops_read_rows_rate | returned, fetched | rows/s |
| postgres.db_ops_write_rows_rate | inserted, deleted, updated | rows/s |
| postgres.db_conflicts_rate | conflicts | queries/s |
| postgres.db_conflicts_reason_rate | tablespace, lock, snapshot, bufferpin, deadlock | queries/s |
| postgres.db_deadlocks_rate | deadlocks | deadlocks/s |
| postgres.db_locks_held_count | access_share, row_share, row_exclusive, share_update, share, share_row_exclusive, exclusive, access_exclusive | locks |
| postgres.db_locks_awaited_count | access_share, row_share, row_exclusive, share_update, share, share_row_exclusive, exclusive, access_exclusive | locks |
| postgres.db_temp_files_created_rate | created | files/s |
| postgres.db_temp_files_io_rate | written | B/s |
| postgres.db_size | size | B |

### Per table

These metrics refer to the database table.

Labels:

| Label      | Description     |
|:-----------|:----------------|
| database | database name |
| schema | schema name |
| table | table name |
| parent_table | parent table name |

Metrics:

| Metric | Dimensions | Unit |
|:------|:----------|:----|
| postgres.table_rows_dead_ratio | dead | percentage |
| postgres.table_rows_count | live, dead | rows |
| postgres.table_ops_rows_rate | inserted, deleted, updated | rows/s |
| postgres.table_ops_rows_hot_ratio | hot | percentage |
| postgres.table_ops_rows_hot_rate | hot | rows/s |
| postgres.table_cache_io_ratio | miss | percentage |
| postgres.table_io_rate | memory, disk | B/s |
| postgres.table_index_cache_io_ratio | miss | percentage |
| postgres.table_index_io_rate | memory, disk | B/s |
| postgres.table_toast_cache_io_ratio | miss | percentage |
| postgres.table_toast_io_rate | memory, disk | B/s |
| postgres.table_toast_index_cache_io_ratio | miss | percentage |
| postgres.table_toast_index_io_rate | memory, disk | B/s |
| postgres.table_scans_rate | index, sequential | scans/s |
| postgres.table_scans_rows_rate | index, sequential | rows/s |
| postgres.table_autovacuum_since_time | time | seconds |
| postgres.table_vacuum_since_time | time | seconds |
| postgres.table_autoanalyze_since_time | time | seconds |
| postgres.table_analyze_since_time | time | seconds |
| postgres.table_null_columns | null | columns |
| postgres.table_size | size | B |
| postgres.table_bloat_size_perc | bloat | percentage |
| postgres.table_bloat_size | bloat | B |

### Per index

These metrics refer to the table index.

Labels:

| Label      | Description     |
|:-----------|:----------------|
| database | database name |
| schema | schema name |
| table | table name |
| parent_table | parent table name |
| index | index name |

Metrics:

| Metric | Dimensions | Unit |
|:------|:----------|:----|
| postgres.index_size | size | B |
| postgres.index_bloat_size_perc | bloat | percentage |
| postgres.index_bloat_size | bloat | B |
| postgres.index_usage_status | used, unused | status |



## Alerts


The following alerts are available:

| Alert name  | On metric | Description |
|:------------|:----------|:------------|
| [ postgres_total_connection_utilization ](https://github.com/netdata/netdata/blob/master/src/health/health.d/postgres.conf) | postgres.connections_utilization | average total connection utilization over the last minute |
| [ postgres_acquired_locks_utilization ](https://github.com/netdata/netdata/blob/master/src/health/health.d/postgres.conf) | postgres.locks_utilization | average acquired locks utilization over the last minute |
| [ postgres_txid_exhaustion_perc ](https://github.com/netdata/netdata/blob/master/src/health/health.d/postgres.conf) | postgres.txid_exhaustion_perc | percent towards TXID wraparound |
| [ postgres_db_cache_io_ratio ](https://github.com/netdata/netdata/blob/master/src/health/health.d/postgres.conf) | postgres.db_cache_io_ratio | average cache hit ratio in db ${label:database} over the last minute |
| [ postgres_db_transactions_rollback_ratio ](https://github.com/netdata/netdata/blob/master/src/health/health.d/postgres.conf) | postgres.db_cache_io_ratio | average aborted transactions percentage in db ${label:database} over the last five minutes |
| [ postgres_db_deadlocks_rate ](https://github.com/netdata/netdata/blob/master/src/health/health.d/postgres.conf) | postgres.db_deadlocks_rate | number of deadlocks detected in db ${label:database} in the last minute |
| [ postgres_table_cache_io_ratio ](https://github.com/netdata/netdata/blob/master/src/health/health.d/postgres.conf) | postgres.table_cache_io_ratio | average cache hit ratio in db ${label:database} table ${label:table} over the last minute |
| [ postgres_table_index_cache_io_ratio ](https://github.com/netdata/netdata/blob/master/src/health/health.d/postgres.conf) | postgres.table_index_cache_io_ratio | average index cache hit ratio in db ${label:database} table ${label:table} over the last minute |
| [ postgres_table_toast_cache_io_ratio ](https://github.com/netdata/netdata/blob/master/src/health/health.d/postgres.conf) | postgres.table_toast_cache_io_ratio | average TOAST hit ratio in db ${label:database} table ${label:table} over the last minute |
| [ postgres_table_toast_index_cache_io_ratio ](https://github.com/netdata/netdata/blob/master/src/health/health.d/postgres.conf) | postgres.table_toast_index_cache_io_ratio | average index TOAST hit ratio in db ${label:database} table ${label:table} over the last minute |
| [ postgres_table_bloat_size_perc ](https://github.com/netdata/netdata/blob/master/src/health/health.d/postgres.conf) | postgres.table_bloat_size_perc | bloat size percentage in db ${label:database} table ${label:table} |
| [ postgres_table_last_autovacuum_time ](https://github.com/netdata/netdata/blob/master/src/health/health.d/postgres.conf) | postgres.table_autovacuum_since_time | time elapsed since db ${label:database} table ${label:table} was vacuumed by the autovacuum daemon |
| [ postgres_table_last_autoanalyze_time ](https://github.com/netdata/netdata/blob/master/src/health/health.d/postgres.conf) | postgres.table_autoanalyze_since_time | time elapsed since db ${label:database} table ${label:table} was analyzed by the autovacuum daemon |
| [ postgres_index_bloat_size_perc ](https://github.com/netdata/netdata/blob/master/src/health/health.d/postgres.conf) | postgres.index_bloat_size_perc | bloat size percentage in db ${label:database} table ${label:table} index ${label:index} |


## Setup

### Prerequisites

#### Create netdata user

Create a user with granted `pg_monitor`
or `pg_read_all_stat` [built-in role](https://www.postgresql.org/docs/current/predefined-roles.html).

To create the `netdata` user with these permissions, execute the following in the psql session, as a user with CREATEROLE privileges:

```postgresql
CREATE USER netdata;
GRANT pg_monitor TO netdata;
```

After creating the new user, restart the Netdata Agent with `sudo systemctl restart netdata`, or
the [appropriate method](https://github.com/netdata/netdata/blob/master/docs/netdata-agent/start-stop-restart.md) for your
system.



### Configuration

#### File

The configuration file name for this integration is `go.d/postgres.conf`.


You can edit the configuration file using the [`edit-config`](https://github.com/netdata/netdata/blob/master/docs/netdata-agent/configuration/README.md#edit-a-configuration-file-using-edit-config) script from the
Netdata [config directory](https://github.com/netdata/netdata/blob/master/docs/netdata-agent/configuration/README.md#the-netdata-config-directory).

```bash
cd /etc/netdata 2>/dev/null || cd /opt/netdata/etc/netdata
sudo ./edit-config go.d/postgres.conf
```
#### Options

The following options can be defined globally: update_every, autodetection_retry.


<details open><summary>Config options</summary>

| Name | Description | Default | Required |
|:----|:-----------|:-------|:--------:|
| update_every | Data collection frequency. | 5 | no |
| autodetection_retry | Recheck interval in seconds. Zero means no recheck will be scheduled. | 0 | no |
| dsn | Postgres server DSN (Data Source Name). See [DSN syntax](https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNSTRING). | postgres://postgres:postgres@127.0.0.1:5432/postgres | yes |
| timeout | Query timeout in seconds. | 2 | no |
| collect_databases_matching | Databases selector. Determines which database metrics will be collected. Syntax is [simple patterns](https://github.com/netdata/netdata/tree/master/src/go/pkg/matcher#simple-patterns-matcher). |  | no |
| max_db_tables | Maximum number of tables in the database. Table metrics will not be collected for databases that have more tables than max_db_tables. 0 means no limit. | 50 | no |
| max_db_indexes | Maximum number of indexes in the database. Index metrics will not be collected for databases that have more indexes than max_db_indexes. 0 means no limit. | 250 | no |

</details>

#### Examples

##### TCP socket

An example configuration.

```yaml
jobs:
  - name: local
    dsn: 'postgresql://netdata@127.0.0.1:5432/postgres'

```
##### Unix socket

An example configuration.

<details open><summary>Config</summary>

```yaml
jobs:
  - name: local
    dsn: 'host=/var/run/postgresql dbname=postgres user=netdata'

```
</details>

##### Unix socket (custom port)

Connect to PostgreSQL using a Unix socket with a non-default port (5433).

<details open><summary>Config</summary>

```yaml
jobs:
  - name: local
    dsn: 'host=/var/run/postgresql port=5433 dbname=postgres user=netdata'

```
</details>

##### Multi-instance

> **Note**: When you define multiple jobs, their names must be unique.

Local and remote instances.


<details open><summary>Config</summary>

```yaml
jobs:
  - name: local
    dsn: 'postgresql://netdata@127.0.0.1:5432/postgres'

  - name: remote
    dsn: 'postgresql://netdata@203.0.113.0:5432/postgres'

```
</details>



## Troubleshooting

### Debug Mode

**Important**: Debug mode is not supported for data collection jobs created via the UI using the Dyncfg feature.

To troubleshoot issues with the `postgres` collector, run the `go.d.plugin` with the debug option enabled. The output
should give you clues as to why the collector isn't working.

- Navigate to the `plugins.d` directory, usually at `/usr/libexec/netdata/plugins.d/`. If that's not the case on
  your system, open `netdata.conf` and look for the `plugins` setting under `[directories]`.

  ```bash
  cd /usr/libexec/netdata/plugins.d/
  ```

- Switch to the `netdata` user.

  ```bash
  sudo -u netdata -s
  ```

- Run the `go.d.plugin` to debug the collector:

  ```bash
  ./go.d.plugin -d -m postgres
  ```

### Getting Logs

If you're encountering problems with the `postgres` collector, follow these steps to retrieve logs and identify potential issues:

- **Run the command** specific to your system (systemd, non-systemd, or Docker container).
- **Examine the output** for any warnings or error messages that might indicate issues.  These messages should provide clues about the root cause of the problem.

#### System with systemd

Use the following command to view logs generated since the last Netdata service restart:

```bash
journalctl _SYSTEMD_INVOCATION_ID="$(systemctl show --value --property=InvocationID netdata)" --namespace=netdata --grep postgres
```

#### System without systemd

Locate the collector log file, typically at `/var/log/netdata/collector.log`, and use `grep` to filter for collector's name:

```bash
grep postgres /var/log/netdata/collector.log
```

**Note**: This method shows logs from all restarts. Focus on the **latest entries** for troubleshooting current issues.

#### Docker Container

If your Netdata runs in a Docker container named "netdata" (replace if different), use this command:

```bash
docker logs netdata 2>&1 | grep postgres
```


