ASA Getting Started
The Architecture of Database Applications
Inside Adaptive Server Anywhere
All the information in an Adaptive Server Anywhere database is usually stored in a single database file, which can be copied from one machine to another. It is possible to make databases of several files, but this is generally only required for very large databases.
In addition to the database file, Adaptive Server Anywhere uses two other files when it is running a database. These are the transaction log and the temporary file.
The database file Internally, the database file is composed of pages: fixed size areas of disk. The data access layer reads and writes data one page at a time. Many pages hold the data that is in the database tables, but other pages hold index information, information about the distribution of data within the database, and so on.
The transaction log The transaction log is a separate file that contains a record of all the operations performed on the database. Normally, it has the same name as the database file, except that it ends with the suffix .log instead of .db. It has three important functions.
Record operations on your data to enable recovery You can recreate your database from a backup together with the transaction log if the database file is damaged.
Improve performance By writing information to the transaction log, the database server can safely process your statements without writing to the database file as frequently.
Enable database replication SQL Remote and the MobiLink client utility use this file to replicate the changes to your database on portable computers which are occasionally connected to the network.
The temporary file The temporary file is opened when the database server starts, and is closed down when the server stops. As its name suggests, the temporary file is used while the server is running to hold temporary information. The temporary file does not hold information that needs to be kept between sessions.
The temporary file is stored in your temporary directory. The location of this directory is generally identified by your TEMP environment variable.