Catalog and Metadata

AngaraBase stores metadata for all database objects in a central registry — the SysCatalog. For users, access to metadata is provided via the sys.* system views and introspection functions.

Object Hierarchy

Database objects are organized in a strict hierarchy:

Instance → Database → Schema → Table → Column

Each level has a unique identifier in the SysCatalog. Tables belong to schemas, schemas to databases, and databases to the instance.

SysCatalog

SysCatalog is the central metadata registry. It stores information about:

tables, columns, and their data types
indexes and constraints
users, roles, and privileges
functions and aggregates
security policies (RLS)
statistics for the query optimizer

The SysCatalog is updated during DDL operations (CREATE, ALTER, DROP) and when statistics are gathered.

System Views (sys.*)

System views are read-only and do not require special privileges (with the exception of security-related views).

Instance Identification and State

View	Description
`sys.identity`	Instance identity: version, instance_id
`sys.health`	Server health status
`sys.settings`	Effective configuration (name, value). Secrets are not exposed

Data Structure

View	Description
`sys.tables`	All tables with metadata (schema, name, type, row count)
`sys.columns`	Columns for each table: column_name, data_type, nullable, etc.

Statistics

View	Description
`sys.table_stats`	Table-level statistics: stats_level_max, last_committed_rowid, mutation epochs
`sys.column_stats`	Column-level statistics: ndv_approx, min/max, null_count, histograms, MCV

Security and Access

View	Description
`sys.users`	User accounts
`sys.roles`	Roles
`sys.user_roles`	Assignments of users to roles
`sys.role_privileges`	Role privileges
`sys.object_grants`	Object-level grants
`sys.my_privileges`	Current user’s privileges
`sys.security_policies`	RLS policies
`sys.audit_log`	Audit log

Introspection Functions

AngaraBase provides a set of built-in functions for programmatic access to metadata.

Roles and Privileges

Function	Purpose
`angara_user_roles()`	Current user’s roles
`angara_role_privileges()`	Privileges of a given role
`angara_user_privileges()`	Effective user privileges
`angara_object_privileges()`	Privileges on a specific object
`angara_has_privilege()`	Check for a specific privilege

Security (RLS, audit, break-glass)

Function	Purpose
`angara_table_policies()`	RLS policies for a table
`angara_is_rls_active()`	Whether RLS is active for a table
`angara_effective_rls_predicate()`	The final RLS predicate for the current user
`angara_break_glass_status()`	Status of the break-glass session
`angara_audit_verify_chain()`	Verify the integrity of the audit chain

Diagnostics and Performance

Function / View	Purpose
`angara_stat_activity`	Active sessions and running queries
`angara_stat_statements`	Aggregated statistics for executed queries
`angara_top_queries()`	Top queries by resource consumption
`angara_stat_statements_reset()`	Reset query statistics

Practical Examples

Instance Information

SELECT * FROM sys.identity;

Checking Server Health

SELECT * FROM sys.health;

List All Tables

SELECT * FROM sys.tables;

Checking Security Settings

SELECT name, value FROM sys.settings WHERE name LIKE 'security.%';

Viewing Table Column Statistics

SELECT column_name, ndv_approx, null_count
FROM sys.column_stats
WHERE table_name = 'orders';

Checking Current User Privileges

SELECT * FROM sys.my_privileges;
SELECT angara_has_privilege('orders', 'SELECT');

Quickstart (sys.* examples) — first steps with system views
Security — security introspection functions
Diagnostics — monitoring and troubleshooting
Query Processing — how the optimizer uses catalog metadata

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