SQL/MX 2.x Installation and Management Guide (H06.10+, J06.03+)

Creating an SQL/MX Database
HP NonStop SQL/MX Installation and Management Guide—544536-007
7-4
Resource Forks
For more information about file naming, see the SQL/MX Reference Manual.
Resource Forks
NonStop SQL/MX maintains substantial information about data files in companion files
known as resource forks. Resource forks are located in the same volume and
subvolume as data files and have the same name as their corresponding data file, with
the final “0” (zero) changed to “1” (one).
Resource forks contain similar information to Guardian file labels, but have the
capacity to store a much greater variety and quantity of information. Examples of data
fork/resource fork pairs are:
•
$DATA.ZSDADMM8.WDE6TI00 / $DATA.ZSDADMM8.WDE6TI01
•
$DATA.ZSDADMM8.HEPQTI00 / $DATA.ZSDADMM8.HEPQTI01
•
$DATA.ZSDADMM8.SS8BSI00 / $DATA.ZSDADMM8.SS8BSI01
Data files are sometimes referred to as data forks to distinguish them from resource
forks. Under normal circumstances, you are not expected or permitted to refer explicitly
to resource forks by name. The one significant exception is TMF recovery using
Guardian file names.
Designating Wild Cards in SQL/MX Schema Names
An SQL/MX schema has a designated subvolume in which every partition belonging to
that schema must reside. Therefore, in general, a Guardian wild card of the form
$*.subvolume.* can serve as convenient shorthand for every Guardian file in the
SQL/MX schemas whose schema subvolume is subvolume.
For more information about the CREATE SCHEMA statement, see the SQL/MX
Reference Manual.
Using the LOCATION Clause
Both CREATE TABLE and CREATE INDEX include a LOCATION clause for specifying
the physical locations of partitions. The complete syntax for this LOCATION clause is:
LOCATION [\node.]$volume[.subvolume.file-name]
[NAME partition-name]
Note. If you do not specify a subvolume name for a schema’s partitions when you
create a schema, NonStop SQL/MX provides a unique subvolume name by default. In
doing this, NonStop SQL/MX establishes and maintains a one-to-one correspondence
between schemas and subvolumes, which is desirable when you use subvolume wild
cards. Unless you have a compelling reason for specifying your own subvolume
names, you should allow NonStop SQL/MX to choose them for you. Otherwise, it is
your responsibility to preserve this one-to-one correspondence. In addition, all files in a
schema subvolume are SQL/MX files. The DP2 process does not allow other types of
files to be created in a schema subvolume.