Difference between revisions of "C-ISAM Data Files"
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=Accessing C-ISAM Data Files= | =Accessing C-ISAM Data Files= | ||
Revision as of 16:53, 24 March 2009
Accessing C-ISAM Data Files
On UNIX and Linux platforms, Recital Terminal Developer, Recital Mirage Server and the Recital Database Server support access to Informix compliant C-ISAM files.
Data access is achieved through a C-ISAM Bridge. This requires the creation of a Bridge file and an empty Recital table that has the same structure as the C-ISAM file.
Creating the Recital Table Create a Recital table with the same structure as the C-ISAM file. The fields/columns in the structure file must exactly match the data type and length of those in the C-ISAM file. The Recital table will have one byte more in total record length due to the Recital record deletion marker.
To create the table, use the SQL CREATE TABLE command or the Recital Terminal Developer CREATE worksurface. The table should be given a ’.str’ file extension (rather than the default ’.dbf’) to signify that this is a structure file only.
Please see the end of this section for information on matching Informix and Recital data types.
Creating the Bridge File In Recital Terminal Developer, the Bridge File can be created using the CREATE BRIDGE worksurface. For Recital Database and Mirage Server clients, the Bridge File can be created in two ways: by using an ’ini’ file, or by the SQL CREATE BRIDGE command.
Maximums Widths The following maximum widths apply to the bridge elements:
Element | Maximum Width in Characters | Description |
---|---|---|
Type | 10 | Bridge type: CISAM |
External | 80 | External file name |
Metadata | 80 | Recital ’structure’ table name |
Alias | 10 | Alias name |
’ini’ file
Firstly, an ’ini’ file should be created on the server in the data directory where the C-ISAM file is held. The ini file has the following structure:
[bridge] bridgetype=<bridgetype> externalname=<name of the C-ISAM file> databasename=<name of the Recital structure table> alias=<the name to use to access your file>
e.g. cisamdemo.ini
[bridge] bridgetype=CISAM externalname=cisam.dat databasename=cisamstru.str alias=cisamdemo
NOTE: There should be no white space either side of the ’=’ signs.
The Bridge file can now be created from the ini file. This can be given a ’.dbf’ file extension (rather than the default ’.brg’) so that it can be accessed like a normal Recital table. The SQL EXECUTE IMMEDIATE command is used to run the Recital/4GL CREATE BRIDGE FROM command:
e.g.
create bridge cisamdemo.dbf from cisamdemo
CREATE BRIDGE (SQL) The CREATE BRIDGE SQL command defines and creates the bridge in one step:
e.g. exec sql CREATE BRIDGE cisamdemo.dbf TYPE "CISAM" EXTERNAL "cisamdemo.dat" METADATA "cisamdemo.str" ALIAS "cisamdemo";
//or
exec sql CREATE BRIDGE cisamdemo.dbf AS "TYPE=CISAM;EXTERNAL=cisamdemo.dat;METADATA=cisamdemo.str;ALIAS=cisamdemo";
Using the Bridge The Bridge can now be used. To access the C-ISAM file, use the ’alias’ specified in the Bridge definition.
e.g.
Select * from cisamdemo
Data Types
Informix | Recital |
---|---|
Byte | Numeric |
Char | Character |
Character | Character |
Date | Date |
Datetime | Character |
Decimal | Numeric |
Double Precision | Float |
Float | Real |
16 Bit Integer | Short |
Integer | Numeric |
Interval | Character |
32 Bit Long | Integer |
Money | Numeric |
Numeric | Numeric |
Real | Numeric |
Smallfloat | Numeric |
Smallint | Numeric |
Text | Unsupported |
Varchar | Character |