A set is an owner record and, optionally, its member records. There are three types of pointers: next, prior and owner, but only next is required. There are five possible orders for arrangements of sets; they are: first - insert at beginning, last - insert at end of set, next - insert after current of set, prior - insert prior to current of set and sorted - insert according to sort value.

Algis kantautas

• Mar 21st, 2007

A.By Codasyl conception SET is data chain between Owner and Member record. B.Pointers: NEXT,PRIOR,OWNER(direct adresation to OWNER_RECORD from MEMBER).At least NEXT pointer is requered to navigate via set.C. Number of sets really  is unlimited.

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IDD is the Integrated Data Dictionary. It contains information about the elements, record types, sets, maps and dialogues within the database.

Algis Kantautas

• Mar 21st, 2007

Integrated Dictionary Directory. IDD - it is metaschema where are stored other "entities" of IDMS components -  elements, records, maps,dialogs,areas, subschemas, schemas.

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Calc is based on a symbolic value which is used to determine the target page. Via mode is for members only. Via records are stored near to their owners. In direct mode the target is specified by the user and is stored as close as possible to that page.

rohit

• Mar 8th, 2007

three modes calc,via,direstcalc: here any fileld value in the record is converted into a combination of page no and line no by means of a hashing algo... to be  staright one can access the record...

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Region is used synonymously with area. It is a group of logically contiguous pages.

test

• Jun 23rd, 2005

Regarding Server Move

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A run-unit is a logical unit of work; it is analogous to a CICS task.

A junction record is a member record type that allows for many-to-many relationship between its two owner records. For a school database the CLASS record is a junction for the TEACHER and SUBJECT record types.

It rolls back (reverses) all database updates to the point of the last rollback or to the beginning of the run-unit.

It releases all database resources, terminates database processes, writes statistical information to IDMS and logs the checkpoint.

It generates a bind run-unit and binds all the records for the sub-schema the program is referencing.

Autostatus is a protocol mode which causes the expansion of each DML statement to include a perform IDMS-Status statement.

It places a record in the database based on the location mode specified.

It will connect to all sets where it is defined as an automatic member. The store requires that currency be established for all these set occurrences.

The old joke - where the programmer thinks he is, but the DBMS knows he is not. Currency is the location within the database during run-unit execution. There are four levels of currency: current of run-unit is the record occurrence of the last successful find or obtain; current of record type is for the most recent of each record type; current of record set is the most recent within each set and...

Store the record then connect it to each set where it is a manual member.

Mandatory and optional.

Erase cancels the membership of a record in specific set occurrences and removes only the named record. Erase permanent removes the specific record and all mandatory occurrences it owns. It disconnects all optional members. Erase selective removes the record, all mandatory members and all optional members not connected to other sets. It disconnects those that are connected. Erase all removes the...

Locks may be shared or exclusive. Shared means that other run units can retrieve the record but can not modify it. Exclusive means that other run units can neither retrieve nor modify it. Record locks may be implicit or explicit. Implicit locks are set in the ready statement usage clause. Explicit locks are set using either the keep statement or keep option of the find/obtain command.

Locks are released by a change in currency or by a commit, rollback or finish command.

Nn29 means that two run units are waiting to set locks on the same record and are in deadlock.

Find tells you whether the record is actually in the database. If it is not found you save the overhead of an obtain.