The sysmaster Database

The database server creates and maintains the sysmaster database. It is analogous to the system catalog for databases, which is described in the IBM® Informix® Guide to SQL: Reference. Just as a system catalog for every database managed by the database server keeps track of objects and privileges in the database, a sysmaster database for every database server keeps track of information about the database server.

The sysmaster database contains the system-monitoring interface (SMI) tables. The SMI tables provide information about the state of the database server. You can query these tables to identify processing bottlenecks, determine resource usage, track session or database server activity, and so on. This chapter describes these tables, which are slightly different from ordinary tables.

Warning: The database server relies on information in the sysmaster database. Do not change any of the tables in sysmaster or any of the data within the tables. Such changes could cause unpredictable and debilitating results.

The database server creates the sysmaster database when it initializes disk space. The database server creates the database with unbuffered logging. You cannot drop the database or any of the tables in it, and you cannot turn logging off.

As user informix on UNIX or a member of the Informix-Admin group on Windows, you can create SPL routines in the sysmaster database. (You can also create triggers on tables within sysmaster, but the database server never executes those triggers.)

Joins of multiple tables in sysmaster might return inconsistent results because the database server does not lock the tables during a join. You can join sysmaster tables with tables in other databases. However, to join sysmaster tables with tables in a nonlogging database, first make the nonlogging database the current database.