IMAGE/SQL: Part 3 of 5
Fred White
Adager Corporation
Sun Valley, Idaho 83353-3000 U.S.A.
In Part 2, I discussed global defects in the program IMAGESQL.PUB.SYS (IMAGESQL) which make it difficult for Database Administrators (DBAs) to maintain their SQL DBEnvironments (DBEs) and their IMAGE/SQL databases (DBs).


Rather than advocating a total redesign of the DBE data structures and the IMAGESQL command set, I resigned myself to accepting the current design and simply recommended modifications intended to minimize the impact of these global defects and make the DBA's job easier.
In this part I discuss the current (July 1994) versions of the IMAGESQL commands “SET SQLDBE”, “SET TURBODB”, “ATTACH” and “ADD USER”.


“SET SQLDBE” is a parameter-setting command to which subsequent DBE-relative commands are applied. Implementation flaws include:


“SET TURBODB” is a parameter-setting command which (as recommended in Part 2 of N) should be available only to the database creator (DBC).
IMAGE is a top-down system. It is important for the DBC to review and perform all IMAGE-to-SQL mappings at the database (DB) level. (Refer to Part 2 of N where I suggested a “MAP” command for providing the functionality of the current UPDATE TYPE and SPLIT commands at the DB level.)
The ideal place for keeping DB level mapping information is in the root file. The SET TURBODB command should automatically generate that table (if not already present) and all manual mappings should be performed prior to attachment to a DBE.
(Note that the SET TURBODB command fails if the root file is currently being accessed exclusively or if the database is being accessed with a DBOPEN mode of 2, 3, 4, 6, 7 or 8.)


“ATTACH” is another command that only the DBC should be allowed to use (as mentioned in Part 2 of N). It has several defects:


“ADD USER”, in addition to needlessly requiring a DBOPEN PASSWORD (see Part 2 of N), has the following defects:

To be continued ...

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