In an Informix database that uses fragmented tables, where is the fragment information stored internally by the database engine?

Introduction / Context:
This question tests understanding of where Informix stores metadata about table fragmentation. Fragmentation information describes how data is distributed across dbspaces and is needed for query planning, backup, and administration. Knowing where this information resides helps administrators understand catalog structures and backup implications.

Given Data / Assumptions:

The database engine is Informix or compatible with its fragmentation model.

Tables may be fragmented by expression, round robin, or other schemes.

The engine must track which fragments exist and where they are located.

Different internal storage areas exist, such as system catalogs, logs, and reserved pages.

Concept / Approach:
Informix uses system catalog tables to store metadata about database objects, including tables, indexes, and fragmentation schemes. These catalog tables record fragment definitions, dbspace assignments, and related information. Physical logs and reserved pages have other purposes, such as tracking transactions or internal state, but do not primarily store fragmentation definitions.

Step-by-Step Solution:
1. Recall that system catalog tables in Informix hold definitions of tables, columns, indexes, and fragments. 2. Understand that physical logs record changes for recovery, not structural metadata. 3. Note that reserved pages store bootstrap and configuration information, not detailed fragmentation schemes. 4. The first page of a database tblspace describes basic tablespace information but not full fragment definitions. 5. Therefore, the correct answer is that fragment information is stored in system catalog tables.

Verification / Alternative check:
Database utilities and queries against catalog tables, such as systables and sysfragments, can be used to view fragment definitions. This confirms that metadata is stored in catalog tables rather than in log files.

Why Other Options Are Wrong:
Physical logs are used for transaction recovery and roll forward, not for storing structural definitions.
Reserved pages store low level engine configuration and are not the primary repository for detailed fragmentation metadata.
The first page of a tblspace includes control information but not complete fragment mapping the way catalog tables do.

Common Pitfalls:
Learners sometimes assume that any internal structure, such as logs or reserved pages, might hold structural metadata. In reality, catalog tables are designed to be queryable and to provide a single source of truth for object definitions. Understanding this helps when scripting administrative tasks.

Final Answer:
Fragment information is stored in the system catalog tables.