Overview of Database Management System (DBMS) Part – 7

Data Dictionary or Data Directory

An individual can describe a data dictionary or data directory as a Database Management system (DBMS) module which keeps the description of information appearances as well as associations. An individual might recall that this “information about information” was considered as metadata. The Database Management system (DBMS) data dictionary or data directory offers the Database Management system (DBMS) with its self-describing distinctive. In use, the data dictionary or data directory is be similar to the replica of the business’s whole information group, as well as is a vital component in the information management function.

The two (2) key categories of data dictionary or data directory are – combined as well as standalone. A combined data dictionary or data directory is involved with the Database Management System (DBMS). For an instance, every relational Database Management System (DBMS) contain an in built data dictionary or data directory which is regularly opened as well as simplified by the Relational Database Management System (RDBMS). Additional Database Management System (DBMS) particularly the outdated types, does not have an in built data dictionary or data directory in its place the Database Administrator (DBA) has to use third party standalone data dictionary or data directory systems.

Data dictionaries or data directories can be categorized as an active or passive data dictionary or data directory too. An active data dictionary or data directory is spontaneously updated by the Database Management System (DBMS) with every single database access, in that way keeping its access data current. While a passive data dictionary or data directory is not spontaneously updated in addition it generally needs a batch process to be executed. Data dictionary or data directory access data is normally castoff by means of the Database Management System (DBMS) intended for query optimization determination.

In data dictionary or data directory the foremost function is to stock the definition of every items which network with the database. Combined data dictionaries or data directories try to bound their metadata to the data managed by means of the Database Management System (DBMS). Standalone data dictionary or data directory systems are generally more flexible as well as permit the Database Administrators (DBA) to define plus handle every organization’s information, irrespective of whether they are computerized or not. Whatsoever the data dictionary or data directory format may be, its presence offers database developer as well as end users with a much better-quality skill to connect. Furthermore, the data dictionary or data directory is the tool which assistances the Database Administrator to solve the information conflicts.

Though, there is no regular layout for the data stored in the data dictionary or data directory more than a few structures are common. For an instance, the data dictionary or data directory usually stocks explanations of all the below listed things:

· Information features which are describe in every tables or relations of all databases. Precisely the data dictionary or the data directory stocks the name, presentation format, data types, inner storing arrangements, as well as authentication guidelines. The data dictionary or data directory expresses where a component is castoff, and by whom it is castoff.

· Tables or relations describe in all databases. For an instance, the data dictionary or data directory is possibly to stock the name of the table or relation designer, the date of formation, right of use permissions, the number of columns or attribute.

· Indexes describe for every single database tables or relations. For every index the Database Management System (DBMS) stocks as a minimum – the index name, the attributes or columns castoff, the position of the index, the particular index features as well as the formation date.

· Describe databases like who formed every single database, the date of formation, where the database is sited, who is the Database Administrator (DBA) is.

· Who are the end users as well as who are or is the administrators of the database.

· Software package which has right of using the database counting the screen presentations, report layouts, application organizations, Structured Query Language (SQL) queries.

· Right of using approval for every end users of every databases.

Associations between the information components where the components includes whether the association is obligatory or else noncompulsory, the connectivity as well as cardinality.

If the data dictionary or data directory can be systematized to contain information outside to the Database Management System (DBMS) itself, it develops a particularly flexible for more overall commercial resource organization. The organization of such a widespread data dictionary or data directory, as a consequence, makes it likely to handle the practice as well as distribution of every single business information irrespective whether it has its origins in the database information. This is the reason why a number of managers think through the data dictionary or data directory to be the main element of the data resource organization function. In addition this is why the data dictionary or data directory may be defined as the data resource dictionary or directory too.

The metadata kept in the data dictionary or data directory is frequently the foundations for checking the database usage as well as the right to use of the database by the end users. The data kept in the database is generally grounded on the relational table or relation arrangement, as a consequence, allowing the Database Administrator (DBA) to query the database with Structured Query Language (SQL) code. For an instance, Structured Query Language (SQL) code can be castoff to mine data about the end users of the exact table or relation or about the right to use of specific end users.

Database Administrators (DBA) and Database End Users

The main aim of a database application is to recover data from as well as stock fresh data in the database. Individuals who work with a database can be classified as database end users or database administrators (DBA).

Database Administrator (DBA)

One of the chief causes of making using of Database Management Systems (DMBS) is to centralize the management of both the information as well as the software programs which access that information. An individual who own such type of significant control over the database application is known as a Database Administrator (DBA). The roles of a Database Administrator (DBA) are comprised of:

· Schema description – The Database Administrator (DBA) forms the new database schema by means of implementing a group of information description code in Data Definition Language (DDL).

· The Database Administrator (DBA) defines the storing arrangement as well as right to use description of the information.

· Schema as well as physical association alteration – The Database Administrator (DBA) transmits the alterations to the schema in addition to physical association to imitate the altering wants of the business, otherwise to change the physical association to increase the performance.

· Allowing the approval for information access – By allowing dissimilar kinds of permission, the database administrator (DBA) can control which portions of the database several end users can access. The approval data is saved in a distinct system structure which the database application refers every time somebody tries to access the information in the application.

· Routine upkeep – the Database Administrator (DBA) is responsible for an upkeep of the database application too. Instances of the database administrator’s routine upkeep jobs are:

o From time to time taking back up of the database, either in the tapes or in the remote servers, to stop data loss in case of any tragedies.

o Safeguarding that sufficient free disk space is obtainable for standard processes, as well as improving the disk space as and when essential.

o Observing jobs executing on the database application as well as confirming that performance is not ruined by means of very expensive jobs given in to by certain end users.

In the upcoming part we will be discussing the Database End Users plus End User Interfaces and the Database Management System (DBMS) Architecture plus Information Independence.