Ingres Files
An Ingres instance includes the following files:
• System files (executables)
• Database files
These files include the master database and user databases. The master database, iidbdb, stores information about all databases, their locations, and the users who can access them.
• Transaction log file
This file stores uncommitted transactions and buffers committed transactions before they are written to the database. Ingres uses one logical instance-wide log file. The file is circular and wraps when it encounters the physical end-of-file.
Each logical log file may consist of up to 16 physical disk files, referred to as partitions, which helps to alleviate I/O bottlenecks. To ensure that no committed transactions are lost if the primary transaction log devices fail, Ingres can maintain a backup of the primary transaction log file, also known as a dual log, on the storage locations you specify.
• Checkpoint files, journal files, dump files
Checkpoint, journal, and dump files provide for data recovery in case of a database disk failure.
Checkpoints alone provide for data recovery up to the time of the checkpoint.
Checkpoints and journals provide for recovery up to the time of failure.
Checkpoint, journal, and dump files provide online checkpoints.
• Temporary work files
Work files are temporary files created during external sorts and other DBMS Server operations that require large amounts of temporary file space.