![]() ![]() That is, it is the master database within an Informix instance that keeps track of all databases within that instance. The sysmaster database is the database of databases. It does not present any unique backup requirements. When a table is partitioned across multiple dbspaces, the portion of the table that resides in a single dbspace is called a fragment. That is, you can restore a single dbspace. Although Informix backups usually are done on the instance level, restores can be done on the dbspace level. A dbspace contains one or more tblspaces. dbspaceĪ dbspace is a storage element that consists of one or more chunks. ![]() They may or may not be physically contiguous. That is, it is a logical grouping of the extents within a chunk that are allocated to a table. The space that a table occupies within a chunk. If not, it again will allocate another extent. It will try to allocate physically contiguous pages if it can. As a table grows, the existing extents that a table is using are used up, and Informix will allocate additional pages for that table. If it cannot allocate enough space in one contiguous section, other extents will be created as necessary. ![]() Informix then will allocate as many contiguous pages as possible to satisfy this request. When you create a table in Informix, you specify the amount of space in kilobytes. ExtentĪn extent is a logical grouping of at least four physically contiguous pages. PageĪn Informix page is a physically contiguous portion of a chunk. A chunk can be either a raw partition or a filesystem file. ChunkĪ chunk is a physical portion of disk on which Informix stores its data. BLOB spaceĪll Informix Binary Large Object (BLOB) data is kept inside the database, but there is a special dbspace for BLOB data. However, a DBA who isolated a database by putting it into a separate dbspace then could recover that database by recovering that dbspace. Informix cannot recover a single database inside an instance. When Informix is started or stopped, these processes appear and disappear. It is represented by one or more oninit processes. An Informix instance is a single connection to shared memory. ![]()
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