Kbase 17792: AS/400 Join Logical Files And The Progress/400 DataServer
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
1/7/2005 |
|
Status: Unverified
GOAL:
Does Progress/400 DataServer architecture support the use of DB2/400 Join Logical files?
FIX:
It has recently been uncovered that the Progress/400 DataServer architecture cannot fully support the use of DB2/400 Join Logical files. There have been scenarios where OS/400 limitation prevents the DataServer from functioning as expected.
The Progress environment has a concept of RECID that is similar in nature to the DB2/400 concept of relative record numbers. Each record read from a DB2/400 file has a relative record number that is unique for the file being read. However, since a join logical file is joining two or more physical files into one "view", the relative record returned is that of the primary file. There is a very good
possibility that the same relative record number (RRN) is returned when reading a join logical file.
This problem can be illustrated using the two files below.
customers orders
--------- ---------
custnum custid
name ordernum
contact orderdate
The records in the file are as follows:
CUSTOMERS:
RRN custnum name contact
--- ------- -------------------- -------------
1 15 Hoopla Basketball Robert Johns
2 16 Thundering Surf Inc. Fran Horan
3 17 High Tide Sailing Angela Tackle
ORDERS:
RRN custid ordernum orderdate
--- ------ -------- ---------
1 15 58 01/29/93
2 16 23 01/12/93
3 16 41 01/20/93
4 16 134 03/09/93
5 17 112 02/29/93
6 17 154 03/18/93
The joined file is created using customer as the primary and custnum
is joined to custid in orders. When the join file is read, one record
will be returned for each record in the secondary file.
When the join file is read the following data is returned:
Row RRN custnum name contact ordernum orderdate
--- --- ------- -------------------- ------------- -------- ---------
1 1 15 Hoopla Basketball Robert Johns 58 01/29/93
2 2 16 Thundering Surf Inc. Fran Horan 23 01/12/93
3 2 16 Thundering Surf Inc. Fran Horan 41 01/20/93
4 2 16 Thundering Surf Inc. Fran Horan 134 03/09/93
5 3 17 High Tide Sailing Angela Tackle 112 01/29/93
6 3 17 High Tide Sailing Angela Tackle 154 03/18/93
As displayed, non unique relative record numbers are returned. This
in itself is a problem so the Progress/400 DataServer constructs a
unique RRN whenever a joined logical file record is read. This newly
constructed unique number is returned to the client as a RECID. The
client can then function properly except in the following instance:
When a browser is used and a reposition is attempted, the client sends
a read request to the server using a RECID. Since the RECID is built
and not a real number, the join file is repositioned to the wrong
record. Since the RECID returned to the client is never "correct",
the client cannot use it to achieve expected results. This problem is
an OS/400 limitation and cannot be corrected in the Progress environment.