16.3 System Catalog Reference

The system catalog is a set of read-only tables for querying Machbase server metadata and current operational status with SQL. It contains two types of tables.

Type	Prefix	Description
Metadata tables	`M$`	Schema information, including table definitions, columns, indexes, and users
Virtual tables (dynamic views)	`V$`	Current operational status, including sessions, running queries, memory, and storage

General Rules

All system catalog tables are read-only. INSERT, UPDATE, and DELETE return errors.
M$ tables automatically reflect DDL operations (CREATE, ALTER, and DROP).
V$ tables reflect live server status and return current values on each query.
Use the following queries to list all tables.

-- List all metadata tables
SELECT name FROM m$tables ORDER BY name;

-- List all virtual tables
SELECT name FROM v$tables WHERE name LIKE 'V$%' ORDER BY name;

Subsections

Section	Description
Metadata Table Dictionary	Schema metadata tables such as M$SYS_TABLES and M$SYS_COLUMNS
Virtual Table Dictionary	Dynamic views such as V$SESSION, V$STMT, and V$PROPERTY
Per-tag Statistics Views	Time- and distance-axis schemas and queries for `V$<TABLE>_STAT`
V$ROLLUP Dictionary	Rollup job status view columns
V$STORAGE_MOUNT_* Dictionary	Mounted backup database view columns
Complete Virtual Table Reference	All entries from the original 8.5 virtual table reference

Last updated on Sep 9, 2026