System

client.System() names the singleton system: no I/O, no failure, and no name, because one schema is one installation. Register declares the system’s own knobs, the built-in alert schedules and the metrics collector, and is safe to run on every startup. A stream’s Register creates the system with defaults if it is absent, so most programs never call it.

err := client.System().Register(ctx, &sqlstreams.SystemConfig{
	PartitionCountAlert: &sqlstreams.PartitionCountAlertConfig{ScheduleExpression: "0 * * * *"},
	MetricCollector:    &sqlstreams.MetricCollectorWorkerConfig{PollRate: 10 * time.Second},
})
if err != nil {
	return err
}

Verbs

verb	returns	notes
Register(ctx, cfg)	error	creates the schema and the control-plane tables when missing (SQL0064 when the role cannot); nil cfg is the defaults; a differing redeclaration replaces the stored worker rows
Get(ctx)	*System	the comma-ok read: (nil, nil) when no system is registered
Migrate(ctx, targetVersion)	error	moves the control-plane tables to a version (migrations)
MigrationVersion(ctx)	int64	the version the control-plane tables are at; ErrNotRegistered
MigrateStreams(ctx, targetVersion)	error	moves every registered stream to a version
Destroy(ctx, options)	error	deletes every stream, schedule, consumer group, worker, and the control-plane tables; ErrDestroyDisabled unless ClientConfig.AllowDestroy; ErrSystemLive and ErrStreamsRegistered unless DestroyOptions.Force
Bindings(ctx)	[]*Binding	every group’s effective binding set and any declarer still waiting, ordered by stream then group; a group reading the whole stream does not appear
Metrics()	*SystemMetricsHandle	no I/O; Metrics
Alerts()	*SystemAlertsHandle	no I/O; Alerts

CLI

sqlstreams system get reads the system registration. Add --quiet for an existence check: no output, exit 0 when registered, exit 1 when absent. --output json returns the system row, or null with exit 1 when absent; it cannot be combined with --quiet.

sqlstreams system binding list reads System().Bindings() across the installation. Use sqlstreams consumer binding get orders.created billing for one consumer’s binding declaration.

Config

SystemConfig

field	default	what it decides
PartitionCountAlert	its own defaults	the partition_count check: ScheduleExpression (@every 1m), Threshold (0, half the lock ceiling Postgres reports), PendingDuration and MaximumGap (two minutes each), and DisablePending (false)
CompactionReadCostAlert	its own defaults	the compaction_read_cost check; ScheduleExpression defaults to @every 1m; PendingDuration and MaximumGap default to two minutes; DisablePending defaults to false
WorkerLivenessAlert	its own defaults	the worker_liveness check; ScheduleExpression defaults to @every 1m; PendingDuration and MaximumGap default to two minutes; DisablePending defaults to false
MetricCollectorProgressAlert	its own defaults	the system-owned collector-progress check; fields below
MetricCollector	PollRate: 30s	how often the collector’s measurement pass runs; zero is the default, negative is rejected

A running collector keeps its rate until its next claim; restart the manager to apply a new one immediately.

MetricCollectorProgressAlertConfig

field	default	what it decides
ScheduleExpression	@every 1m	how often collector progress is checked
MaximumAge	0	zero uses max(two minutes, three declared collector poll intervals); a positive duration overrides it
PendingDuration	2m	required unhealthy duration during continuous manager lease coverage
DisablePending	false	permits immediate activation with current manager lease coverage

The default age follows the current collector declaration. An already-running collector keeps its previously claimed rate until its next claim.

Gotchas

• The system is a singleton and a handle anyway. The day that changes, the API grows by one parameter, client.System(name), and client.Stream[T](name) stays the default system’s shortcut.
• The manager is not here. It is a running subsystem with its own handle, client.Manager() (Manager).