IMS DB Tough Questions (1 of 3)

1. In DL/I Database elements are organized in hierarchical structure. There are max 255 segments and 15 levels are possible in a database
2. Q2)Top-Down-Left-Right is the approach data can be accessed-This is called sequential processing
3. Q3)For Random processing, key(sequence) field is required. Through concatenated key (from root segment to the segment that you want), randomly record can be accessed.
4. Q4)DL/I acts as middle layer between Application program and database. Read all imsdb posts here.
5. Q5)DBD tells complete structure of the database. PSB is program’s view of the database. That means, for a DBD, multiple PSBs are possible.
   1. Q6)PROCOPT=G,R,I etc (check my part-1 for more on this)states access permissions on the database. Also, we can call as locks.
6. Q7)ACB-also called access control block.It merges PSBs and DBDs into IMS-internal format when application program starts to execution.

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