RetroBBS - comp.lang.mumps - $Query error when globals are mapped at the subscript level

$Query error when globals are mapped at the subscript level

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Subject: $Query error when globals are mapped at the subscript level
From: aoneill5jhh@gmail.com (Alan O'Neill)
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by: Alan O'Neill - Mon, 14 Nov 2022 19:19 UTC

I believe there is a problem with the $q() function when globals are mapped in the global directory at the subscript level. Here's why.

I have two databases, which I'll call database A (DB-A) and database B (DB-B). They each contain a set of VistA FileMan files stored in a global named ^WEB, and the structure of these files is the same in both databases. We needed DB-B to look to DB-A for all nodes in ^WEB except for ^WEB(3309,*) and ^WEB(3315,*). For these two, DB-B needed to have its own local copy, which resulted in the following [partial] global directory layout for DB-B.

WEB WEB(3309) REG = DBA
SEG = DBA
FILE = /yottadb/dba/mumps.dat
WEB(3309) WEB(3309)++ REG = DEFAULT
SEG = DEFAULT
FILE = /yottadb/dbb/mumps.dat
WEB(3309)++ WEB(3315) REG = DBA
SEG = DBA
FILE = /yottadb/dba/mumps.dat
WEB(3315) WEB(3315)++ REG = DEFAULT
SEG = DEFAULT
FILE = /yottadb/dbb/mumps.dat
WEB(3315)++ WEBERROR REG = DBA
SEG = DBA
FILE = /yottadb/dba/mumps.dat

Here is a partial listing of ^WEB(3315,*) from DB-A:

DB-A>zwrite ^WEB(3315,*)
^WEB(3315,0)="Web System Profile^3315^19^18"
...snip...
^WEB(3315,"IP","pdd17.mycompany.edu",15)=""
^WEB(3315,"IP","wam.mycompany.edu",19)=""

Here is a partial listing of ^WEB(3315,*) in DB-B:

DB-B>zwrite ^WEB(3315,*)
^WEB(3315,0)="Web System Profile^3315^1^1"
...snip...
^WEB(3315,"IP","wam.mycompany.edu",1)=""

Using $q() on this final node in DB-B should return null (or a node in ^WEB that has a first subscript that is greater than 3315). Instead, it is returning the next node in ^WEB(3315,*) from DB-A.

DB-B>w $q(^WEB(3315,"IP","wam.mycompany.edu",1))
^WEB(3315,"IP","wam.mycompany.edu",19)

But that node does not exist in DB-B.

DB-B>w ^WEB(3315,"IP","wam.mycompany.edu",19)
%GTM-E-GVUNDEF, Global variable undefined: ^WEB(3315,"IP","wam.mycompany.edu",19)

Put another way, I would never expect the following line of MUMPS code to fail under any circumstance, yet as you'll see, it does.

DB-B>s g=$na(^WEB(3315)) f s g=$q(@g) q:g="" s x=@g
%GTM-E-GVUNDEF, Global variable undefined: ^WEB(3315,"IP","wam.mycompany.edu",19)

Reactor error - core dumped!

devel / comp.lang.mumps / $Query error when globals are mapped at the subscript level

Subject	Author
$Query error when globals are mapped at the subscript level	Alan O'Neill