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[ravikumar_sri2001]

Hi Gurus,

Assume a Database with four levels and each level has only one Segement-type.i.e, (A-->B--->C---D) and assume that one-to-one relationship in consecutive levels. That is,

A1-->B1--->C1---D1
A2-->B2--->C2---D2
A3-->B3--->C3---D3 and so on.

a. Assume that position is established in C10. If we issue GU call with unqualified SSA in all levels , which occurance will it retrieve in "D".
Is it D1 or D10 ?.

b. Manual says "If IMS has a position established at the missing level, the SSA that IMS uses is derived from that position, as reflected in the DB PCB.". I assumed that this point is applicable for only segments with Key fields.

Suppose there is no key in segment "C" and position is established at C10. If we issue GU call with qualified SSA (A=A1 & B=B1) in first 2 levels and unqualified SSA in third level, how SSA for segment "C" will be built ?.


Thanks,
Ravikumar.

[YSMVS]

Hello Ravikumar,

The basic difference from GU and GN call is that all the references will be from beginning of the database for GU calls and it will be from the current posiition incase of GN call for unqualified calls.

So for your first question unless you qualify all the SSA all references will be from beginning of Database, so it would be D1.

For your second question the segments would be inserted into the database based on the insert rule. So the segment which would be fetched is the first occurence under B1.
_________________
Thanks,
YSMVS

[ravikumar_sri2001]

Hi YSMVS,

Following are the statements taken from IBM manual regarding GU call.

"If you leave out an SSA for one of the levels in a GU call that has multiple SSAs, IMS assumes an SSA for that level. The SSA that IMS assumes depends on current position:

a.If IMS has a position established at the missing level, the SSA that IMS uses is derived from that position, as reflected in the DB PCB.

b.If IMS does not have a position established at the missing level, IMS assumes an unqualified SSA for that level.

c.If IMS moves forward from a position established at a higher level, IMS assumes an unqualified SSA for that level.

d.If the SSA for the root level is missing, and IMS has position established on a root, IMS does not move from that root when trying to satisfy the call. "

My second question is related to GU call not ISRT call.

Thanks,
Ravikumar.

[ravikumar_sri2001]

Hi Gurus,

I just started learning IMS. I got struck up with these GU call doubts. Please help me to understand GU call.

Thanks,
Ravikumar.