Extent sizes for sbspaces

An extent in an sbspace consists of a collection of contiguous pages that store smart large object data.

The unit of allocation in an sbspace is an extent. The database server calculates the extent size for a smart large object from a set of heuristics, such as the number of bytes in a write operation. For example, if an operation asks to write 30 KB, the database server tries to allocate an extent the size of 30 KB.
Important: For most applications, you must use the values that the database server calculates for the extent size.

If you know the size of the smart large object, you can use one of the following functions to set the extent size. The database server allocates the entire smart large object as one extent (if an extent of that size is available in the chunk):

For information about tuning extent sizes, see smart large objects in the chapter on configuration effects on I/O utilization in your HCL Informix Performance Guide.


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