PostgreSQL

Plugin: go.d.plugin Module: postgres

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	postgres.connections_utilization	average total connection utilization over the last minute
postgres_acquired_locks_utilization	postgres.locks_utilization	average acquired locks utilization over the last minute
postgres_txid_exhaustion_perc	postgres.txid_exhaustion_perc	percent towards TXID wraparound
postgres_db_cache_io_ratio	postgres.db_cache_io_ratio	average cache hit ratio in db ${label:database} over the last minute
postgres_db_transactions_rollback_ratio	postgres.db_cache_io_ratio	average aborted transactions percentage in db ${label:database} over the last five minutes
postgres_db_deadlocks_rate	postgres.db_deadlocks_rate	number of deadlocks detected in db ${label:database} in the last minute
postgres_table_cache_io_ratio	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	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	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	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	postgres.table_bloat_size_perc	bloat size percentage in db ${label:database} table ${label:table}
postgres_table_last_autovacuum_time	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	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	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.

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

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 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 script from the Netdata config directory.

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.

Config options

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.	postgres://postgres:[email protected]: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.		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

Examples

TCP socket

An example configuration.

jobs:
  - name: local
    dsn: 'postgresql://[email protected]:5432/postgres'

Unix socket

An example configuration.

Config

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

Multi-instance

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

Local and remote instances.

Config

jobs:
  - name: local
    dsn: 'postgresql://[email protected]:5432/postgres'

  - name: remote
    dsn: 'postgresql://[email protected]:5432/postgres'

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].

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

• Switch to the netdata user.

  sudo -u netdata -s

• Run the go.d.plugin to debug the collector:

  ./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:

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:

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:

docker logs netdata 2>&1 | grep postgres