Configuration Reference

Configuration Reference

All ulak GUC parameters use the ulak. prefix. Set them in postgresql.conf or via ALTER SYSTEM. Parameters with POSTMASTER context require a full server restart to take effect. Parameters with SIGHUP context only need a configuration reload (SELECT pg_reload_conf();). Parameters with SUSET context require superuser privileges.

There are 57 parameters in total across 15 categories.

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Worker Settings

These parameters control background worker processes. Both require a server restart after changes.

Parameter	Type	Default	Range	Context	Description
ulak.workers	int	4	1-32	POSTMASTER	Number of background worker processes
ulak.worker_restart_delay	int	5s	1-300	POSTMASTER	Delay in seconds before restarting a crashed worker

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General Settings

Parameter	Type	Default	Range	Context	Description
ulak.database	string	"postgres"	--	SIGHUP	Database name that background workers connect to
ulak.log_level	enum	warning	error, warning, info, debug	SIGHUP	Extension log verbosity level

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Queue & Polling

Parameter	Type	Default	Range	Context	Description
ulak.poll_interval	int	500ms	100-60000	SIGHUP	Queue polling frequency in milliseconds
ulak.batch_size	int	200	1-1000	SIGHUP	Number of messages processed per batch cycle
ulak.max_queue_size	int	1000000	0-INT_MAX	SIGHUP	Backpressure threshold; 0 disables the limit

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Retry & Backoff

ulak uses a linear backoff strategy. The delay for retry N is calculated as: min(retry_base_delay + (N * retry_increment), retry_max_delay).

Parameter	Type	Default	Range	Context	Description
ulak.default_max_retries	int	10	0-1000	SIGHUP	Default maximum number of delivery attempts
ulak.retry_base_delay	int	10s	1-3600	SIGHUP	Base delay in seconds for backoff calculation
ulak.retry_max_delay	int	300s	1-86400	SIGHUP	Maximum backoff delay in seconds
ulak.retry_increment	int	30s	1-3600	SIGHUP	Linear backoff increment in seconds per retry

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Stale Recovery

Parameter	Type	Default	Range	Context	Description
ulak.stale_recovery_timeout	int	300s	60-3600	SIGHUP	Timeout in seconds after which in-flight messages are considered stuck and eligible for recovery

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Circuit Breaker

The circuit breaker protects endpoints from being overwhelmed during failures. After the threshold is reached, the circuit opens and no messages are dispatched until the cooldown period elapses and a half-open probe succeeds.

Parameter	Type	Default	Range	Context	Description
ulak.circuit_breaker_threshold	int	10	1-1000	SIGHUP	Consecutive failures required to open the circuit
ulak.circuit_breaker_cooldown	int	30s	5-3600	SIGHUP	Cooldown period in seconds before a half-open probe is attempted

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HTTP Settings

Parameter	Type	Default	Range	Context	Description
ulak.http_timeout	int	10s	1-300	SIGHUP	Total HTTP request timeout in seconds
ulak.http_connect_timeout	int	5s	1-60	SIGHUP	TCP connection timeout in seconds
ulak.http_max_redirects	int	0	0-20	SIGHUP	Maximum number of HTTP redirects to follow; 0 disables redirects
ulak.http_ssl_verify_peer	bool	true	--	SIGHUP	Enable SSL peer certificate verification
ulak.http_ssl_verify_host	bool	true	--	SIGHUP	Enable SSL hostname verification
ulak.http_allow_internal_urls	bool	false	--	SUSET	Allow dispatching to internal/private IP addresses (SSRF bypass); requires superuser
ulak.http_batch_capacity	int	200	1-1000	SIGHUP	HTTP batch buffer size
ulak.http_max_connections_per_host	int	10	1-100	SIGHUP	Maximum concurrent connections per host
ulak.http_max_total_connections	int	25	1-200	SIGHUP	Maximum total concurrent HTTP connections
ulak.http_flush_timeout	int	30000ms	1000-300000	SIGHUP	Batch flush timeout in milliseconds
ulak.http_enable_pipelining	bool	true	--	SIGHUP	Enable HTTP/2 multiplexing for improved throughput
ulak.capture_response	bool	false	--	SIGHUP	Store HTTP response body with dispatch result
ulak.response_body_max_size	int	65536	0-10485760	SIGHUP	Maximum response body size to capture in bytes

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Payload & CloudEvents

Parameter	Type	Default	Range	Context	Description
ulak.max_payload_size	int	1048576	1024-104857600	SIGHUP	Maximum message payload size in bytes (default 1 MB)
ulak.cloudevents_source	string	"/ulak"	--	SIGHUP	Source URI used in CloudEvents envelope

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Retention

Parameter	Type	Default	Range	Context	Description
ulak.event_log_retention_days	int	30	1-365	SIGHUP	Number of days to retain event log entries
ulak.dlq_retention_days	int	30	1-3650	SIGHUP	Number of days to retain dead letter queue messages
ulak.archive_retention_months	int	6	1-120	SIGHUP	Number of months to retain archive partitions

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Kafka Settings

Requires the extension to be compiled with ENABLE_KAFKA=1.

Parameter	Type	Default	Range	Context	Description
ulak.kafka_delivery_timeout	int	30000ms	5000-300000	SIGHUP	Delivery confirmation timeout in milliseconds
ulak.kafka_poll_interval	int	100ms	10-1000	SIGHUP	Producer poll interval in milliseconds
ulak.kafka_flush_timeout	int	5000ms	1000-60000	SIGHUP	Batch flush timeout in milliseconds
ulak.kafka_batch_capacity	int	64	16-1024	SIGHUP	Maximum pending messages in producer buffer
ulak.kafka_acks	string	"all"	0, 1, -1, all	SIGHUP	Broker acknowledgment level
ulak.kafka_compression	string	"snappy"	none, gzip, snappy, lz4, zstd	SIGHUP	Message compression algorithm

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MQTT Settings

Requires the extension to be compiled with ENABLE_MQTT=1.

Parameter	Type	Default	Range	Context	Description
ulak.mqtt_keepalive	int	60s	10-600	SIGHUP	Keep-alive interval in seconds
ulak.mqtt_timeout	int	5000ms	1000-60000	SIGHUP	Operation timeout in milliseconds
ulak.mqtt_default_qos	int	0	0-2	SIGHUP	Default MQTT Quality of Service level
ulak.mqtt_default_port	int	1883	1-65535	SIGHUP	Default broker port

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Redis Settings

Requires the extension to be compiled with ENABLE_REDIS=1.

Parameter	Type	Default	Range	Context	Description
ulak.redis_connect_timeout	int	5s	1-60	SIGHUP	Connection timeout in seconds
ulak.redis_command_timeout	int	30s	1-300	SIGHUP	Command execution timeout in seconds
ulak.redis_default_db	int	0	0-15	SIGHUP	Default Redis database index
ulak.redis_default_port	int	6379	1-65535	SIGHUP	Default Redis server port

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AMQP Settings

Requires the extension to be compiled with ENABLE_AMQP=1.

Parameter	Type	Default	Range	Context	Description
ulak.amqp_connection_timeout	int	10s	1-300	SIGHUP	Connection timeout in seconds
ulak.amqp_heartbeat	int	60s	0-600	SIGHUP	Heartbeat interval in seconds; 0 disables heartbeats
ulak.amqp_frame_max	int	131072	4096-2097152	SIGHUP	Maximum AMQP frame size in bytes
ulak.amqp_delivery_timeout	int	30000ms	5000-300000	SIGHUP	Publisher confirm timeout in milliseconds
ulak.amqp_batch_capacity	int	64	16-1024	SIGHUP	Batch buffer size for pending messages
ulak.amqp_ssl_verify_peer	bool	true	--	SIGHUP	Enable SSL peer certificate verification

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NATS Settings

Requires the extension to be compiled with ENABLE_NATS=1.

Parameter	Type	Default	Range	Context	Description
ulak.nats_delivery_timeout	int	5000ms	1000-60000	SIGHUP	JetStream acknowledgment timeout in milliseconds
ulak.nats_flush_timeout	int	10000ms	1000-300000	SIGHUP	Batch flush timeout in milliseconds
ulak.nats_batch_capacity	int	64	16-1024	SIGHUP	Batch buffer size for pending messages
ulak.nats_reconnect_wait	int	2000ms	100-60000	SIGHUP	Reconnect backoff delay in milliseconds
ulak.nats_max_reconnect	int	60	-1 to 10000	SIGHUP	Maximum reconnect attempts; -1 for infinite

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Production Configuration Example

# postgresql.conf — ulak production settings
shared_preload_libraries = 'ulak'

ulak.database = 'myapp'
ulak.workers = 8
ulak.batch_size = 200
ulak.poll_interval = 250
ulak.max_queue_size = 500000

ulak.default_max_retries = 15
ulak.circuit_breaker_threshold = 5
ulak.circuit_breaker_cooldown = 60

ulak.http_timeout = 30
ulak.http_ssl_verify_peer = true
ulak.http_allow_internal_urls = false

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See Also

• Getting Started -- Installation and first steps
• SQL API Reference -- Complete function reference
• Architecture -- Internal design and worker model
• Security -- RBAC roles and access control
• Protocol: HTTP | Kafka | MQTT | Redis | AMQP | NATS