System tables

The system.* introspection tables — queries, query_log, parts, traces, transforms, subscriptions, memory_profile, and more.

NYXDB exposes its internal state as system.* tables you can query with ordinary SQL. Column lists below are from the engine's system-table definitions.

system.queries

Live, in-flight queries (keyed by query_id). It carries a deep per-stage timing breakdown (~90 columns); the most-used:

Column	Type	Meaning
`query_id`	UInt64	Identity
`statement`	String	SQL text
`state`	String	`running` / `streaming`
`started_ms`	UInt64	Start (epoch ms)
`elapsed_us`	UInt64	Wall-clock µs
`ttfb_us`	UInt64	Time to first byte
`rows_scanned` / `rows_returned`	UInt64	Scan vs output
`peak_memory_bytes`	UInt64	Peak tracked memory
`shards_total` / `shards_pruned`	UInt64	Shard pruning
`granules_total` / `granules_pruned`	UInt64	Granule pruning
`scan_us`, `op_filter_us`, `op_aggregate_us`, …	UInt64	Per-stage / per-operator µs

system.query_log

Completed queries with retention (keyed by query_id, retention by ended_ms). Mirrors system.queries plus ok ('0'/'1'), error (verbatim text), and exec_us.

SELECT query_id, exec_us, rows_returned, ok, error
FROM system.query_log
ORDER BY ended_ms DESC
LIMIT 20;

system.parts

Column	Type
`part_id`	String
`relation`	String
`shard_id`	UInt64
`rows`	UInt64
`size_bytes`	UInt64
`min_key` / `max_key`	String
`min_ts` / `max_ts`	UInt64
`disk`	String
`created_at_ms`	UInt64

system.traces

Execution spans with retention (keyed by trace_id, span_id).

Column	Type
`trace_id`, `span_id`, `parent_id`	UInt64
`type`	String (`query`, later `flush`/`compaction`/…)
`subject`, `name`, `kind`	String
`start_us`, `dur_us`, `dark_us`	UInt64
`thread_slot`	UInt64
`shard_id`	Int64 (`-1` if not shard-scoped)
`attrs`	String (`key=value;…`)

system.transforms

Ephemeral — rebuilt each refresh from the catalog and runtime.

Column	Type
`name`	String
`source` / `target`	String
`state`	String
`start`	String
`reflected_position`	String
`lag`	String (nullable)
`rows_emitted`	UInt64
`last_error`	String

Live streaming subscribers and PSI delivery health (keyed by subscription_id): query_id, client, user, psi_lane, psi_pending_events, psi_pending_bytes, psi_overflow_count, psi_delivery_lag_p50_us / _p95_us / _p99_us, and more.

system.memory_profile

Ephemeral top-N allocation sites, refreshed on a memory-pressure tier crossing (keyed by sequence, rank): bytes, allocations, trigger, backtrace. Empty on engines without allocator profiling.

Other system tables

system.metrics (gauges: name, value, description), system.events (counters), system.disks, system.storage_policies, system.column_stats, system.endpoints, system.grants, system.operator_grants, system.users, system.attributes, system.governance_log.

TODO-verify: system.functions and a system.tables catalog view — referenced by name but their column lists are not yet confirmed in the engine.