- 1 What are SGA memory structures?
- 2 What are the memory structures of the Oracle?
- 3 What is Lgwr?
- 4 What is Oracle SGA memory?
What are SGA memory structures?
A system global area (SGA) is a group of shared memory structures that contain data and control information for one Oracle database instance. If multiple users are concurrently connected to the same instance, then the data in the instance’s SGA is shared among the users.
What are the memory structures of the Oracle?
The basic memory structures associated with Oracle include:
- Software Code Areas.
- System Global Area (SGA): the database buffer cache. the redo log buffer. the shared pool.
- Program Global Areas (PGA): the stack areas. the data areas.
- Sort Areas.
What are the components of the SGA?
The SGA consists of the following components.
- Database buffer cache.
- Redo log buffer.
- Shared pool.
- Java pool.
- Large pool (optional)
- Streams pool.
What is the algorithm used in SGA buffer?
The buffer cache uses its own version of the LRU algorithm.
What are the 3 files of physical structure of Oracle Database?
Introduction to Physical Storage Structures
- Data files and temp files. A data file is a physical file on disk that was created by Oracle Database and contains data structures such as tables and indexes.
- Control files. A control file is a root file that tracks the physical components of the database.
- Online redo log files.
What is fixed SGA in Oracle?
The fixed SGA is a component of the SGA that varies in size from platform to platform and release to release. It is “compiled” into the database. The fixed SGA contains a set of variables that point to the other components of the SGA and variables that contain the values of various parameters.
What is Oracle memory?
The Oracle Database In-Memory (Database In-Memory) feature set includes the In-Memory Column Store (IM column store), advanced query optimizations, and availability solutions. The Database In-Memory optimizations enable analytic queries to run orders of magnitude faster on data warehouses and mixed-use databases.
What is memory structure explain in detail?
Memory structures are often classified on the basis of accessibility of data and program memory: This term refers to the case where data and program are accessible through separate hardware. When applied to general-purpose RISC processors, this means that the data and program busses are separated.
What is Lgwr?
Log Writer process (LGWR) is a background Process that writes redo log entries sequentially into redo log file. Redo log entries are generated in the redo log buffer of the SGA. If the database has a multiplexed redo log, then LGWR writes the same redo log entries to all of the members of a redo log file group.
What is Oracle SGA memory?
The System Global Area (SGA) is a group of shared memory structures, known as SGA components, that contain data and control information for one Oracle Database instance. The SGA is shared by all server and background processes. Examples of data stored in the SGA include cached data blocks and shared SQL areas.
What is Oracle database structure with diagram?
An oracle database includes several different types of files: data files, control files, redo files, archive redo log files, parameter files, and password files. An oracle instance has two different sets of components: The set of background processes like PMON, SMON, RECO, etc.
How is the lgwr process used in SGA?
LGWr process writes the contents of log buffers present inside SGA(shared global area) to the logfiles present on the disk. The logfile marked as current will be used for the same in real time. The main focus is to capture all the change vectors that will change the database structure like DML operations (INSERT, UPDATE, DELETE).
When does the lgwr process in Oracle run?
Whenever a user commits the data, LGWr process will always run. Like I said, Oracle Architecture is designed to perform this way. Also when the buffer is one third full, it also provokes the LGWr to perform it’s duty.
What are the memory structures associated with Oracle?
The basic memory structures associated with Oracle Database include: The SGA is a group of shared memory structures, known as SGA components, that contain data and control information for one Oracle Database instance. The SGA is shared by all server and background processes.
What does PGA stand for in Oracle Database?
PGA is the memory reserved for each user process connecting to an Oracle Database and is allocated when a process is created and deallocated when a process is terminated. Private SQL Area: Contains data such as bind information and run-time memory structures.