[Music] hello everyone and welcome back to another video in the course of dbms in this video we will be discussing about the database system environment we have already seen briefly an illustration of a database system environment in our first video here we will be discussing in detail the types of software components in the database system this diagram shows the different component modules in dbms let us look into each of these modules in detail as i mentioned in the previous video once the database design is completed the schemas have to be defined by the database administrator and the database designers so the dpa and its staff uses data definition language or ddl to specify these schemas now the ddl compiler processes the schema definition that is specified in the data definition language and stores these definition or description of the schema in the catalog we know that the catalog contains information like the file size data types storage details of the files constraints etc these modules access the catalog whenever required next we have the query compiler that handles high level queries this query compiler analyzes and interprets the queries by creating a database access code and then it calls a runtime database processor for executing that code then we have the pre-compiler that extracts dml commands or the data manipulation language commands from an application program that is this pre-compiler extracts all the dml commands from the application program written in a host programming language like c c plus plus java etc and these extracted dml commands are sent to the dml compiler where dml compiler is used for compilation of the dml commands into an object code for access to the database so here the dml compiler compiles the extracted dml commands into an object code and other than the dml commands the rest of the program is sent to the host language compiler then the object code and the rest of the program are linked together to form the compiled or the canned transactions and we have learned earlier the canned transactions are used by the parametric or the nav users and this compiled or the canned transactions then generates a call to the runtime database processor and a runtime database processor handles any kind of database accesses at runtime this runtime database processor receives retrieval or update requests and it carries them on the store database finally we have the store data manager and this module of the dbms controls access to the information that is stored on the disk and this module carries out data transfer between the disk and the main memory once the data is in the main memory then it can be processed by other dbms modules and also it can be processed by the application programs so that is all about the different component modules in dbms in addition to these modules most database management systems have database system utilities that help the database administrator to manage the database system let us look at few common utilities and their functions so the common utilities have the following types of functions the first one is loading this utility is used to load existing data files into the database and the source format of the data file and the target or the destination data file format or structure are mentioned to the utility and based on that the utility automatically reformats the data and stores it in the database the next utility that we have is the backup utility this utility creates a backup copy of the database and with this backup copy we can restore the database in case of any kind of system failures incremental backups are also often used in incremental backups only changes since the previous backup are recorded though this is complex it saves space the next type of utility that we have is the file reorganization utility this utility is used to reorganize a database file into a different file organization and why is this required to improve performance next performance monitoring utility as the name suggests monitors the database usage and provides the complete statistics of the performance of the database to the database administrator and the database administrator uses these statistics to decide whether or not to reorganize files to improve performance so these are the different system utilities that we have seen there are other utilities too for sorting files for monitoring the access by the users and for performing other functions next let us look at the other tools that we have there are many other tools available to the database designers the database administrators and also the users we have the case tools or the computer aided software engineering tools that are used during the design of the database another tool called the data dictionary or data repository system is used to store catalog information it also stores other information like descriptions of the application program user information etc so such a system is also called an information repository because it has information that can be accessed directly by the users or the database administrators when required this data dictionary is similar to the dbms catalog just that it has more variety of information which is accessed by the users rather than the dbms software next we have the application development environments as the name clearly suggests these systems provides an environment for developing database applications for example the j builder system power builder system etc dbms also needs the communication software where it allows the users remote access to the database through computer terminals or workstations or their local personal computers they're connected to the database site through phone lines or local area networks or lan etc so these are the different tools that we have in dbms that are available to the database designers and the database administrators with this we come to the end of this video this was all about the database system environment which included the different component modules of dbms the database system utilities and the different tools hope you understood these concepts thank you [Applause] [Music]