Progress
Database Administration
Guide and Reference


Creating a Structure Description File

The structure description file is a text file you prepare that actually defines the database structure. It contains all of the information required by the PROSTRCT CREATE utility to create a database control area.

Use any text editor, such as vi, edit, or the Progress Procedure Editor, to create the structure description file. The name you give to the structure description file is usually the name of the database you define, with a .st extension.

The structure description file is made up of one or more lines of text that provide information about each storage area of the database. Each line of text is composed of tokens, which are text strings made up of alphanumeric characters that describe the following characteristics:

Example Structure Description File

The following example shows the information that is needed in a structure description (ST) file named sports2000.st to define a database with:

The following is a syntax description of the line format for a structure description (ST) file:

CR = blank line 
LINE = comment | areatype pathname [ sizeinfo ] 
comment = * | : | # 
areatype = a | b | d | t [ areainfo ] 
areainfo = [“areaname”[:areanum ][, recsPerBlock ]  ] 
		areaname = string 
		areanum = numeric value 
		recsPerBlock = numeric value 
pathname = . | string  | !”string 2" 
sizeinfo = extentType size 
		extentType = fixed (f) | raw device (r) | variable length (v) 
		size = numeric value > 32 

Note that you can comment the ST file and use blank lines. Precede comments with a pound sign (#), colon (:), or asterisk (*) in the first column of each comment line.

Example Structure Description File For Large Files

When creating a new database, large file processing is enabled if the ST file specifies a fixed length extent size or a maximum size for a variable length extent that is greater than 2 GB. The following example shows the ST file of a database with large file processing enabled.

# Sample Structure Description File: largedb.st 
# 
# largedb.st to create database largedb with large file processing enabled. 
# 
# A fixed length bi file of 1GB and a variable length bi file with a maximum 
# size of 4GB. 
# 
b tests/largedb.b1 f 1048576 
b tests/largedb.b2 v 4194304 
# 
# SCHEMA AREA with a fixed length file of 3GB and a variable length file with 
# a maximum size of 3GB. 
# 
d “Schema Area”:6,64 tests/largedb.d1 f 3145728 
d “Schema Area”:6,64 tests/largedb.d2 v 3145728 
# 
# TABLE AREA with a fixed length file of just over 2GB and a variable length 
# file with a maximum size of 1TB. 
# 
d “Table Area”:7,64 tests/largedb_7.d1 f 2097280 
d “Table Area”:7,64 tests/largedb_7.d2 
# 
# A fixed length ai file of 2GB and a variable length file with a maximum size 
# of 1TB. 
a tests/largedb.a1 f 2097152 
a tests/largedb.a2 
# 

For more information on enabling large file processing, see the "PROUTIL ENABLELARGEFILES Qualifier" section in Database Administration Utilities."

Defining Storage Areas and Extents

Define each storage area and extent on a separate line of text in the ST file. Each line is composed of tokens. The first token of each line identifies the type of storage area to be created. These tokens must be lowercase. Table 4–1 lists each token with the corresponding storage area type.

Table 4–1: ST File Tokens and Storage Areas 
Token
Type of Storage Area
a
After-image (AI) Area
b
Primary Recovery (BI) Area
d
Schema Area and Application Data Areas
t
Transaction Log (For Two-phase Commit)

Extent Pathnames and Naming Conventions

If the first token defines an application data storage area (d), add an area name after it. Then, the next token defines the file pathname. This pathname must represent a standard operating system file. The only pathname restrictions are those that might be imposed by your operating system’s create and read permissions for a particular file.

NOTE: In a structure description (ST) file, to specify a pathname that contains spaces (such as \usr1\misc data), precede the pathname with an exclamation point (!) and wrap the pathname in quotation marks ( “ “). For example, !”\usr1\misc data”.

The PROSTRCT CREATE utility is designed to allow the end user to specify the minimum amount of information necessary to create a database. Only the area type and extent location must be specified. A specific filename or file extension need not be provided.

The utility will generate filename and file extensions for all database files according to the following naming convention:

Rules For Creating Storage Areas and Extents

When you are defining storage areas and extents in order to create a new database:

Extent Length

You can specify a fixed-length or variable-length extent:


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