Using Multiple Rdb DBMS Files

Example: Completing Setup and Metadata Creation Steps for Multiple Rdb DBMS Files

This example illustrates the setup and metadata creation steps for multiple Rdb DBMS files. The example assumes that an Rdb DBMS file with all tables is available as a template dictionary and for use in metadata creation. You can adapt this example to suit your needs.

1. Determine what Rdb files are needed. For this example, the file names are:

   CORPTABLES.RDB, 

   CORPDATA2006.RDB

   CORPDATA2007.RDB

   CORPDATA2008.RDB

   These files reside in the directory DISK$DUA0:[RDB].

   CORPTABLES is an empty DBMS template that is cloned for each year's data and provides a dictionary for use in the synonym creation process. In addition, logicals that match the physical file names are used to avoid the Rdb 31-character physical limit and to facilitate coding in case the location changes in the future.

2. To ensure that the logicals are always available (and known to the server at start up time), edit the following file

   EDACONF [.BIN]EDAENV.COM

   and add a logical name reference (of 31 characters or less) for each Rdb DBMS file to be accessed. For example:

   $ DEFINE CORPTABLES   DISK$DUA0:[RDB]CORPTABLES.RDB

   $ DEFINE CORPDATA2006 DISK$DUA0:[RDB]CORPDATA2006.RDB

   $ DEFINE CORPDATA2007 DISK$DUA0:[RDB]CORPDATA2007.RDB

   $ DEFINE CORPDATA2008 DISK$DUA0:[RDB]CORPDATA2008.RDB

   Save your changes.

   Note:

   • If a generic application setup batch file with the desired logical is available and does not force a process exit, you can call that batch file from EDAENV.COM and avoid the individual entries described above.
   • If the desired logicals are already available, you can skip this step altogether because the logicals are automatically issued when you boot your machine.
3. Assuming you have edited the EDAENV file as described in step 2, start or restart your server.
4. During Rdb adapter configuration, choose the standard options for enabling Rdb data access and supply the following logical name for the server:

   CORPTABLES:

   The resulting profile entry would looks as follows:

   ENGINE SQLRDB SET SERVER CORPTABLES:

5. Using the Web Console's edit facility or another editor, modify the global profile, edasprof.prf (or possibly a group or user profile if you are configuring for group or personal profile-based behavior) to add an ATTACH ALIAS command for each of the additional Rdb files. This step will make the Rdb database files visible as aliases to the default database. For this example, the following code was added after the SET SERVER line in the profile:

   ENGINE SQLRDB SET SERVER CORPTABLES:

   SQL RDB ATTACH 'ALIAS CORPDATA2006 FILENAME CORPDATA2006:' ;
   END
   SQL RDB ATTACH 'ALIAS CORPDATA2007 FILENAME CORPDATA2007:' ;
   END
   SQL RDB ATTACH 'ALIAS CORPDATA2008 FILENAME CORPDATA2008:' ;
   END 

   Note:

   • The semi-colon and END statements are required.
   • The ATTACH statements must follow the initial SET SERVER command. (Placement before the SET SERVER command will cause a crash.)
   • You can issue additional SET SERVER statements after the ATTACH statements.
6. At this point, if you have metadata from a prior installation it is good practice to determine if you can use your existing metadata as is, if you need to modify it, or if you need to create new (additional) metadata that is distinct from what already exists. Depending on your needs, you may be done or you may need to continue with either Step 7 or Step 8.
   • For new installations (that is, those with no prior metadata), continue with Step 7.
   • In releases prior to 7.6.8, a synonym was either prefixed or not prefixed depending on how the metadata was created or, possibly, edited at a later time for a specific value. If the metadata for a given table is available and the TABLENAME=value attribute in the Access File points at the appropriate SQL alias.tablename (or is not prefixed for data that uses the default connection), then there is no need to modify the given synonym in order to access the data. If all synonyms are of this type and no additional new metadata is desired, you are done.
   • If additional new synonyms are desired, or if prefixes on existing synonyms need to change, continue with Step 7 to create the new metadata and then go to Step 8 to edit the Access File TABLENAME=value for the existing and new synonyms.
7. Whether you are creating a synonym for the first time or re-creating a synonym that existed in a prior release, you can use the Web Console or the DMC synonym creation facility. When prompted, select the desired Rdb tables using the connection:

   CORPTABLES:

8. After any needed metadata has been created, edit the Access Files that needs to change (using the Web Console editor or another editor) to have a TABLENAME= value that is prefixed with the appropriate ALIAS reference.

   To complete this step from the Web Console, locate the synonym whose Access File you need to edit, click it, and select Edit Access File as Text from the menu.

   For instance, in the Access File TABLENAME entry for the 2007 Sales table initially looks like this:

   TABLENAME='RDB$HANDLE.SALES',

   The single quotation marks are required since the $ in RDB$HANDLE is regarded as a special character.

   The edited version would look as follows:

   TABLENAME='CORPDATA2007.SALES',

   In this instance, the single quotation marks are optional since CORPDATA2007 does not contain a special character.

9. Repeat step 8, as many time as necessary to account for all metadata whose access requires an ATTACH ALIAS command.

   Tip: As an alternative to editing each file individually, you can create a batch script that edits the RDB$HANDLE string for groups of files at one time.

Tip: An orderly approach is to create all of the synonyms, repeat the reconfiguration step as needed, then edit the Access Files.