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Naming Conventions and File Extensions
Omnidex uses a standard set of file extensions, suffixes,
when dealing with file types specific to the software, some
required and some optional. Following is a list of required
and recommended file extensions:
.src |
Omnidex Environment Source File - Recommended, assumed
if omitted. |
.env |
Omnidex Environment File
(Compiled Environment Source File)
Required, assumed if omitted. |
.tdf |
Tab-Delimited File
Recommended. |
.ost |
Omnidex Stand-Alone Table
Required. |
.ofx |
Offset Index
Required. |
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Limitations
- Each filespec, including the full path and file name,
is limited to 255 characters in length. This is a POSIX
limitation.
- Where multiple files are allowed, there is no limit as
to the number of files passed, as long as each individual
filespec adheres to the 255 character limit.
- When using environment variables, the output of the translation
of the environment variables is limited to 255 characters.
- When using the contents of a file, the output of the file
is limited to 255 characters.
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Environment Variables
Environment variables can be used anywhere that file names
are used. They can be passed in place of, or in conjunction
with, a file name.
Omnidex supports operating system syntax as well as its own,
universal syntax, for using environment variables.
For example, assume the environment variable APPLICATION_HOME
has been set to point to the main application directory on
a server. The syntax to reference that environment variable,
in the INDEXPREFIX declaration in the Omnidex Environment
file for example, is as follows:
Windows Syntax
INDEXPREFIX %APPLICATION_HOME% "\idx\orders"
UNIX Syntax
INDEXPREFIX $APPLICATION_HOME "/idx/orders"
Omnidex Universal Syntax
INDEXPREFIX {$APPLICATION_HOME "/idx/orders"}
This last example will translate the line to the proper operating
system syntax.
Note that it is not possible to use system commands like "cat"
or "type" when using the Omnidex Universal Syntax.
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Passing Multiple File Names
Omnidex supports the use of multiple files in some places
like the PHYSICAL clause of the TABLE section in the Omnidex
Environment file. Multiple file names can be passed in two
ways:
- using a wildcard character
- using a comma-separated list of files
Wildcard Character
The syntax for passing multiple file names with a wildcard
card character is much like the operating system syntax. Each
file must adhere to the 255 character length
limit, however, there is no limit to the number of files
that can be included with this wildcard character.
For example, assume there are serveral .dat files in the
same directory, they can be referenced by:
data/*.dat
data/sales*.dat
sales2003.*
*.*
Comma-Separated List
Multiple files can be passed using a comma-separated list
of file names. Each file spec must adhere to the 255 character
length limit, however, there is no limit to the number of
files that can be passed in the comma-separated list.
PHYSICAL "data/sales1.dat,data/sales2.dat,data/sales3.dat,data/sales4.dat"
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Using File Contents as Arguments
Omnidex supports the use of file contents as an argument.
To accomplish this, use the system command, cat on Unix and
type on Windows, to display the contents of a text file to
the screen. Omnidex will use the value output with this command
as the argument value where used.
For example, the default user name can be stored in a file
(username.txt) and passed using the cat or type system command.
USER type "username.txt"
The contents of username.txt are used at the USER argument.
Note that it is not possible to use these system commands
in conjunction with the Omnidex Universal syntax.
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Examples
Environment Variables
In this example, you want to make Omnidex put all of the
Omnidex index files into the idx sub-directory
of the main application directory, c:\omnidex,
and prefix these index files with the filename "orders".
In this example, an environment variable called APPLICATION_HOME
points to this main application directory. You'll set the
INDEXPREFIX clause of the DATABASE
statement in the Omnidex Environment file to use this environment
variable, as follows:
INDEXPREFIX "%APPLICATION_HOME%\idx\orders"
This will cause all of the index files to be created
as follows:
c:\omnidex\idx\orders0A
c:\omnidex\idx\orders0B
c:\omnidex\idx\orders0C
...
The above example is on a Windows machine, however, the same
can be accomplished on a Unix machine using Unix syntax.
Multiple Environment Variables can be concatenated together
to form a single argument value. For example, assume the following
environment variables have been set:
APPLICATION_HOME = "/usr/omnidex/"
DATA_FILES = "datafiles/currentyear/"
SALES_DATA = "sales.dat"
The PHYSICAL clause of the TABLE
section in the Omnidex Environment file can look like this:
PHYSICAL "{$APPLICATION_HOME$DATA_FILES$SALES_DATA}"
Multiple Files Using a Wildcard Character
In this example, there are several .dat files located in
the data subdirectory of the application's home directory.
These .dat files are going to be defined together as a single
table Physical clause of the Table section in the Omnidex
Environment file.
TABLE Sales
 PHYSICAL
"{$APPLICATION_HOME /data/*.dat}"
Multiple Files Using a Comma-Separated List of Files
The previous example can also be accomplished by concatenating
all of the filenames together into a comma-separted list.
TABLE Sales
PHYSICAL
{"data/january.dat,data/february.dat,data/march.dat,data/april.dat,
data/may.dat,data/june.dat,data/july.dat,data/august.dat,data/september.dat,
data/october.dat,data/november.dat,data/december.dat"}
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