FAQs(121 to 135)

121) What will the DB2 optimizer do?

A) The optimizer is a DB2 component that processes SQL statements and selects the access paths.

122) What is a page?

A) This is the unit of storage within a table space or indexspace that is accessed by DB2.

123) What is pagespace?

A) Pagespace refers to either to an unpartitioned table, to an index space, or to a single partition of a partitioned table of index space.

124) What is a predicate?

A) A predicate is an element of a search condition that expresses or implies a comparison operation.

125) What is a recovery log?

A) A recovery log is a collection of records that describes the sequence of events that occur in DB2. The information is needed for recovery in the event of a failure during execution.

126) What is a Resource Control Table(RCT)? Describe its characteristics.

A) The RCT is a table that is defined to a DB2/CICS region. It contains control characteristics which are assembled via the DSNCRCT macros. The RCT matches the CICS transaction ID to its associated DB2 authorization ID and plan ID(CICS attachment facility).

127) Where are plans stored?

A) Each plan is defined uniquely in the SYSIBM.SYSPLANS table to correspond to the transaction (s) that are to execute that plan.

128) What is meant by repeatable read?

A) When an application program executes with repeatable read protection, rows referenced by the program can?t be changed by other programs until the program reaches a commit point.

129) Describe what a storage group(STOGROUP) is?

A) A STOGROUP is a named collection of DASD volumes to be used by tablespaces and index spaces of databases. The volumes of STOGROUP must be of the same device type.

130) How would you move a tablespace (using STOGROUP) to a different DASD volume allocated to that tablespace?

A) If the tablespace used is only allocated to that STOGROUP:

- ALTER STOGROUP - add volume (new) delete volume(old)


Create a new STOGROUP that points to the new volume. ALTER the tablespace and REORG or RECOVER the


131) What is the format (internal layout) of ?TIMESTAMP??

A) This is a seven part value that consists of a date (yymmdd) and time(hhmmss and microseconds).

132) What is meant by a unit of recovery?

A) This is a sequence of operations within a unit of work(i.e., work done between commit points).

133) Can DASD types assigned to storage groups be intermixed(i.e., 3350s and 3380s)?

A) No

134) What are the three types of page locks that can be held?

A) Exclusive, update, and share.

135) Can DB2 be accessed by TSO users? If yes, which command is used to invoke DB2?

A) DB2 can be invoked by TSO users by using the DSN RUN command.