What is oracle 10g1/2/2023 ![]() ![]() The logical layer of the database consists of the following elements: ![]() Oracle provides a mechanism for storing multiple copies of control files. ![]() One or more control files-Control files contain information used to start an instance, such as the location of datafiles and redo log files Oracle needs this information to start the database instance. If redo log information is lost, you cannot recover the system. The redo log files must perform well and be protected against hardware failures (through software or hardware fault tolerance). This information is used in the event of a system failure to reapply changes that have been made and committed but that might not have been made to the datafiles. Redo log files, known as the redo log, store a log of all changes made to the database. Two or more redo log files-Redo log files hold information used for recovery in the event of a system failure. The number of datafiles that can be configured is limited by the Oracle parameter MAXDATAFILES. Spreading tablespaces over many datafiles can have a significant positive effect on performance. The information for a single table can span many datafiles or many tables can share a set of datafiles. You can have as few as one datafile or as many as hundreds of datafiles. One or more datafiles-Datafiles store the information contained in the database. The physical layer of the database consists of three types of files: The physical layer consists of the files that reside on the disk the components of the logical layer map the data to these physical components. The Oracle database has a logical layer and a physical layer. ![]()
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