Oracle Database - Wikipedia. Oracle Database (commonly referred to as Oracle RDBMS or simply as Oracle) is an object- relational database management system. SDL developed the original version of the Oracle software. The name Oracle comes from the code- name of a CIA- funded project Ellison had worked on while formerly employed by Ampex. An instance—identified persistently by an instantiation number (or activation id: SYS. V. Typical processes include PMON (the process monitor) and SMON (the system monitor). Oracle documentation can refer to an active database instance as a . The SGA typically holds cache information such as data- buffers, SQL commands, and user information. In addition to storage, the database consists of online redo logs (or logs), which hold transactional history. Processes can in turn archive the online redo logs into archive logs (offline redo logs), which provide the basis for data recovery and for the physical- standby forms of data replication using Oracle Data Guard. The Oracle RAC (Real Application Clusters) option uses multiple instances attached to a central storage array. 2 Oracle WebLogic Server Issues. This chapter describes issues associated with Oracle WebLogic Server. It includes the following topics: JDK 7 Certification. Microsoft SQL Server Migration Assistant (SSMA) for Oracle is a tool to automate migration from Oracle database to SQL Server and Azure SQL DB. Microsoft SQL Server Migration Assistant (SSMA) for Oracle is a tool to automate migration from Oracle database(s) to SQL Server, Azure SQL DB and Azure SQL Data. Developer.com, the Flagship of the Developer.com Network, is the developer's source for in-depth programming tutorials and relevant development news across all major. In version 1. 0g, grid computing introduced shared resources where an instance can use CPU resources from another node in the grid. The advantage of Oracle RAC is that the resources on both nodes are used by the database, and each node uses its own memory and CPU. Information is shared between nodes through the interconnect—the virtual private network. PL/SQL (Oracle Corporation's proprietary procedural extension to SQL), or the object- oriented language Java can invoke such code objects and/or provide the programming structures for writing them. Storage. Segments in turn comprise one or more extents. Extents comprise groups of contiguous data blocks. Data blocks form the basic units of data storage. A DBA can impose maximum quotas on storage per user within each tablespace. Specific partitions can then be added or dropped to help manage large data sets. Monitoring. The SYSTEM tablespace contains the data dictionary, indexes and clusters. A data dictionary consists of a special collection of tables that contains information about all user- objects in the database. Since version 8i, the Oracle RDBMS also supports . Version 1. 0g and later introduced the SYSAUX tablespace, which contains some of the tables formerly stored in the SYSTEM tablespace, along with objects for other tools such as OEM, which previously required its own tablespace. DBAs can manage these files manually or leave their administration to Oracle itself. Note that a datafile has to belong to exactly one tablespace, whereas a tablespace can consist of multiple datafiles. Redo log files, recording all changes to the database – used to recover from an instance failure. This tutorial shows you how to migrate a Microsoft SQL Server database to Oracle Database 11g using Oracle SQL Developer. Place the cursor over this icon to load and.Often, a database stores these files multiple times for extra security in case of disk failure. Identical redo log files are associated in a . They are necessary (for example) when applying changes to a standby database, or when performing recovery after a media failure. One can store identical archive logs in multiple locations. Tempfiles: These special datafiles serve exclusively for temporary storage data (used for example during large sorts or for global temporary tables)Control files, necessary for database startup. Oracle Corporation defines a control file as . After the installation process sets up sample tables, the user logs into the database with the username scott and the password tiger. The name of the SCOTT schema originated with Bruce Scott, one of the first employees at Oracle (then Software Development Laboratories), who had a cat named Tiger. Most recent. The information in the SGA consists of the following elements, each of which has a fixed size, established at instance startup: Every Oracle database has one or more physical datafiles, which contain all the database data. The data of logical database structures, such as tables and indexes, is physically stored in the datafiles allocated for a database. Datafiles have the following characteristics: One or more datafiles form a logical unit of database storage called a tablespace. A datafile can be associated with only one tablespace. Datafiles can be defined to extend automatically when they are full. Data in a datafile is read, as needed, during normal database operation and stored in the memory cache of Oracle Database. For example, if a user wants to access some data in a table of a database, and if the requested information is not already in the memory cache for the database, then it is read from the appropriate datafiles and stored in memory. Modified or new data is not necessarily written to a datafile immediately. To reduce the amount of disk access and to increase performance, data is pooled in memory and written to the appropriate datafiles all at once. The instance writes redo log buffers to the redo log as quickly and efficiently as possible. The redo log aids in instance recovery in the event of a system failure. SGA stores shared- memory structures such as shared SQL areas in the library cache and internal information in the data dictionary. An insufficient amount of memory allocated to the shared pool can cause performance degradation. Large pool Optional area that provides large memory allocations for certain large processes, such as Oracle backup and recovery operations, and I/O server processes. Database buffer cache: Caches blocks of data retrieved from the database. KEEP buffer pool: A specialized type of database buffer cache that is tuned to retain blocks of data in memory for long periods of time. RECYCLE buffer pool: A specialized type of database buffer cache that is tuned to recycle or remove block from memory quicklyn. K buffer cache: One of several specialized database buffer caches designed to hold block sizes different from the default database block size. Java pool: Used for all session- specific Java code and data in the Java Virtual Machine (JVM)Streams pool: Used by Oracle Streams to store information required by capture and apply. When you start the instance by using Enterprise Manager or SQL*Plus, the amount of memory allocated for the SGA is displayed. If multiple applications issue the same SQL statement, each application can access the shared SQL area. This reduces the amount of memory needed and reduces the processing- time used for parsing and execution planning. Data dictionary cache. The data dictionary contains information such as: user information, such as user privilegesintegrity constraints defined for tables in the databasenames and datatypes of all columns in database tablesinformation on space allocated and used for schema objects. The Oracle instance frequently accesses the data dictionary to parse SQL statements. Oracle operation depends on ready access to the data dictionary—performance bottlenecks in the data dictionary affect all Oracle users. Because of this, database administrators must make sure that the data dictionary cache. Without enough memory for the data- dictionary cache, users see a severe performance degradation. Allocating sufficient memory to the shared pool where the data dictionary cache resides precludes this particular performance problem. Program Global Area. Every server or background process has its own PGA, the total of PGA elements is call Instance PGA. The size and content of the PGA depends on the Oracle- server options installed. This area consists of the following components: stack- space: the memory that holds the session's variables, arrays, and so onsession- information: unless using the multithreaded server, the instance stores its session- information in the PGA. In a multithreaded server, the session- information goes in the SGA.)private SQL- area: an area that holds information such as bind- variables and runtime- bufferssorting area: an area in the PGA that holds information on sorts, hash- joins, etc. DBAs can monitor PGA usage via the system view. Dynamic performance views. Typical operating environments might include – temporarily or permanently – some of the following individual processes (shown along with their abbreviated nomenclature). The default binary equivalent server parameter file (. Within an SQL- based environment, the views V$PARAMETER. Database administrators have limited access to Oracle- internal C structures via V$ views and their underlying X$ . Lungu and V. From Oracle. The researchers concluded that . Configurable destinations for such records can include: background dump (bdump) destination: contains files generated when an Oracle process experiences unexpected problems. Variations between versions cover the names of days and months, abbreviations, time- symbols (such as A. M. Critical Patch Updates (CPUs) and Security Alerts come out quarterly on the Tuesday closest to 1. Releases and versions. With the Oracle RDBMS 1. Oracle Corporation began using the . Instead, the letters . A fully featured edition of Oracle Database, it also allows purchase of add- on features in the form of Database Options and Management packs and imposes no limitation on server resources available to the database. Oracle Database XE is a separate product from the rest of Oracle Database product family. It provides a subset of Standard Edition functionality (lacking features such as Java Virtual Machine, managed backup and recovery and high availability), is community- supported and comes with its own license terms. It is available for purchase for Windows and Linux platforms only and does not include management packs. It was largely the same as the current SE2 offer, including Real Application Clusters option at no additional cost, however allowing twice as much CPU sockets in a server or a cluster. Standard Edition One (SE1), introduced with Oracle 1. SE and was licensed to run on single servers with a maximum of two CPU sockets. Oracle Corporation discontinued SE and SE1 with the 1. December 1, 2. 01. Technical Information for Software Developers. Anatomy of a Software Development Role: Data Scientist. The expansion of data requires a set of techniques and skills that are unlike historical approaches to data that we have been using.
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