SAS Scalable Performance Data Server 4.5, Administrator'S Manual

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Table Metadata .mdf Very small 1
Table Data .dpf Large 1 to many
Segmented Index(es) .idx Medium to Large 0 or more
Global Index(es) .hbx Medium to Large 0 or more
Creating SPD Server Component Files
Which Component Files Are Created for SPD Server Tables?
At a minimum, an SPD Server table consists of two component files, the metadata .mdf
file and the data .dpf file. The size of the data file component depends on two factors: the
size of a table column and the number of columns.
The data .dpf component file can be many gigabytes in size. SPD Server is not constrained
by an operating system file system size limit. (Many readers are familiar with the 2-gigabyte
limit on file size that some UNIX systems impose.)
Which Component Files Are Created for Indexes on SPD Server
Tables?
The SPD Server index uses two index component files: the .hbx file and the .idx file.
The .hbx file maintains a global view of the index, and contains an entry for each key that
exists in the index. The .idx file maintains a segmented view of the index that includes a
list of all of the segments that each key is a member of. A bitmap is used to determine the
per-segment observations for each key.
The size of the .hbx file depends on the cardinality of the index keys. The higher the
cardinality of the index keys, the larger the .hbx file. The size of the .idx file is much more
difficult to determine because it depends on how the data for the index keys is distributed
across segments. An index key that is in many segments will require a larger segment list,
and larger segment lists require a larger number of per-segment bitmaps, as compared to
an index key that is found only in a small number of segments.
The best case scenario for creating an optimally sized .idx file occurs when the table is
sorted by the indexed columns, in order to minimize the number of segments that the key
is in. The worst case scenario for creating an optimally sized
.idx file occurs when the index
keys are in a large number of segments, with a low cardinality of rows for each segment.
Configuring LIBNAME Domain Disk Space
The SPD Server system administrator defines the primary file system for each LIBNAME
domain for the SPD Server user base. If desired, the system administrator can choose to
define initial and overflow storage locations for the
.dpf data component files as well as
the two index component ( .hbx and .idx ) files.
Example 1: Primary File System Storage for All Component Files
The primary file system is the base directory that you assign to the LIBNAME domain by
issuing a PATHNAME= statement in the SPD Server LIBNAME parameter file,
libnames.parm . Here is an example of a libnames.parm parameter file entry:
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Chapter 10 • Configuring Disk Storage for SPD Server