In which of the following is the size of the buffer used during an online backup defined ?
a. DB2_backupsz registry variable
b. DBM configuration of database instance.
c. DBM.INI file for the database instance
d. DB configuration for database being backed up.
Given the following :
CREATE TABLE tab1(col1 int CONSTRANT notnull CHECK(col1 IS NOT NULL), col2 CHAR(10)
which of the following will enforce uniqueness of col1 which currently does not contain duplicate values ?
a.Create primary key on col1.
b.Create unique index on col1
c.Create a cluster index on col1
d.Create unique constrant on col1
backbufsz : This parameter specifies the size of the buffer used when backing up the database when a value is not explicitly specified in the backup utility.
Here is the explanation:
If the statement was unique constraint, then Db2 will automatically create a unique index. Since it is notunique constraint a unique index has to be created. There is a difference between defining a unique constraint and creating a unique index. Both enforce uniqueness, a unique index allows nullable columns and generally cannot be used as a primary key.