Technologies/PostgreSQL/postgresql.connection.max
PostgreSQLPostgreSQLMetric

postgresql.connection.max

Max connections allowed
Dimensions:None
Available on:OpenTelemetryOpenTelemetry (1)DatadogDatadog (1)
Interface Metrics (2)
OpenTelemetryOpenTelemetry
Configured maximum number of client connections allowed
Dimensions:None
DatadogDatadog
The maximum number of client connections allowed to this database.
Dimensions:None
Sources
postgresql.connection.maxgithub.com
postgresql.max_connectionsgithub.com

Technical Annotations (21)

Configuration Parameters (6)
pool_moderecommended: transaction
Returns connection after each transaction, recommended for most use cases
default_pool_sizerecommended: 20
Actual database connections per database/user pair
max_client_connrecommended: 1000
Maximum application connections to pooler
query_timeoutrecommended: 30
Kill queries running longer than 30 seconds to prevent connection starvation
max_connections
defines maximum simultaneous connections allowed
superuser_reserved_connectionsrecommended: 3
Connection slots reserved for superusers to maintain admin access during exhaustion
Error Signatures (2)
FATAL: sorry, too many clients alreadylog pattern
FATAL: remaining connection slots are reserved for non-replication superuser connectionslog pattern
CLI Commands (5)
SELECT query, calls, total_exec_time, mean_exec_time, rows FROM pg_stat_statements ORDER BY total_exec_time DESC LIMIT 20;diagnostic
ulimit -ndiagnostic
SELECT count(*), state FROM pg_stat_activity GROUP BY state;diagnostic
SELECT pid, usename, application_name, state, query_start, state_change FROM pg_stat_activity WHERE state = 'idle';diagnostic
SELECT pg_terminate_backend(pid) FROM pg_stat_activity WHERE state = 'idle' AND state_change < NOW() - INTERVAL '1 hour';remediation
Technical References (8)
PgBouncercomponent/etc/pgbouncer/pgbouncer.inifile pathcheck_postgrescomponentmax_connectionscomponent/etc/security/limits.conffile pathpg_stat_activitycomponentpg_terminate_backend()componentpostgresql.conffile path
Related Insights (7)
Connection limit exhaustion causes memory pressure and context-switching overheadcritical
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Connection count approaching max_connections causes connection failurescritical
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Insufficient file descriptor limit prevents server startupcritical
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Connection exhaustion prevents new client connectionscritical

Each PostgreSQL connection consumes 5-10MB RAM via fork model. At 200 connections: 1-2GB RAM overhead before queries run. At 500+ connections: excessive context-switching dominates query execution time. Database becomes unresponsive under concurrent load.

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Connection slots exhausted preventing new client connectionscritical
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Connection failure when requests exceed default 100 connection limitcritical
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Connection exhaustion blocks new client connectionscritical
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