DB2 is a Database Management System for the MVS Operating System where, DB2 is a subsystem of MVS Operating System.
The data changes can be made permanent by using COMMIT. It also permits data to be accessed by other applications who can reference the committed data
1. SMALLINT 2. INTEGER 3. FLOAT 4. DECIMAL 5. CHAR 6. VARCHAR 7. DATE 8. TIME
It is specified as a condition or criteria to ensure data integrity. A value to be inserted or updated to a table is tested by CHECK constraint. The CHECK constraints are created during the creation of the table.
The process that builds access paths to the DB2 table is known as bind. The bind uses Database Request Modules from the DB2 pre-compile step as input and produces an application plan. It checks for user authentication and validates SQL statements in the DBRM(s).
The buffer pool is a reserved main storage, which is to satisfy the buffering requirements for one or more table spaces or indexes. It can be made up of either 4K or 32K pages.
The physical database is managed by the DB2 component called Data manager. It invokes other system components to perform logging, locking etc.
STOGROUP is a named collection of DASD volumes, which is to be used by index spaces and table spaces of the database.
Predicate is an element of a search condition. It expresses or implies a search condition.
Declaration Generator is a facility that is used to form SQL statements that describes a table or view. At pre-compile time, the table or view descriptions are then used to check the validity of SQL statements.
Clustering index is a type of index, which locates the table rows and determines how to group the rows together in the tablespace.
More than one DB2 application process can access the same data at the same time, is known as concurrency. However, problems can happen such as, lost updates access to unrepeatable reads and uncommitted data.
Data manager can be considered as a component that is capable of managing the databases that are physically present and is capable of invoking other components associated with the system for performing functionalities like logging, locking and in performing other I/O operations.
DBRM stands for Database Request Module and is a component inside DB2, which is created by the pre compiler of DB2. This is a module that consists of SQL source statements that get extracted out of the application program. DBRMs form inputs that are helpful in the binding process.
Data page can be considered as a unit that is capable of retrieving data from the database. The database from which the data can be retrieved is in the form of 4 kilobytes or 32 kilobytes. The form in which data is retrieved depends on the way the table is defined inside the database. Data page also contains information regarding the catalog or user that are part of the database.
RCT is expanded as Resource – Control Table and is defined in the DB2/CICS region. This is the component that comprises of features that are gathered through macros of DSNCRCT. RCT matches with the transaction ID that of CICS, with the authorization ID that of DB2. This should also be matched with plan ID.
Tablespace that you are using is allocated only to STOGROUP, then you can enter the command ALTER STOGROUP for adding as well as deleting volume. REORG TABLESPACE and RECOVER TABLESPACE are statements that are helpful in creating new STOGROUP that can point towards the new volume. ALTER tablespace and REORG and RECOVER are statements used for altering and recovering the tablespace allocated in the memory.
Load utility is used to load data into tables.
Reorg utility is used for reorganization of data on physical storage.