# System catalogs The system catalogs are the place where users can access schema metadata, such as information about tables and columns, and other bookkeeping information. Subsalt supports two standard system catalogs: `pg_catalog` and `information_schema`. All catalog tables are read-only, and can be queried with standard SQL statements. ### pg\_catalog `pg_catalog` is [Postgres' system catalog](https://www.postgresql.org/docs/current/catalogs.html) and contains information about tables, namespaces, data types, and many other entities. Subsalt supports the full schema for all tables for compatibility reasons, though some values don't apply to generative databases and aren't populated. ### information\_schema `information_schema` is the ANSI SQL standard system catalog and contains information about entities common to all relational databases (tables, columns, etc). Subsalt supports the [set of tables supported by Postgres](https://www.postgresql.org/docs/current/information-schema.html). --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.subsalt.io/configuration/creating-synthetic-databases/system-catalogs.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.