Automatic memory management enables Oracle Database to manage and tune the database memory automatically. In automatic memory management mode, management of the shared global area (SGA) and program global area (instance PGA) memory is handled completely by Oracle Database.
- What is difference between SGA and PGA?
- What is the purpose of SGA in Oracle?
- What is automatic memory management in Oracle?
- Why PGA is used in Oracle?
- What is large pool in Oracle?
- What is UGA in Oracle?
- What is Sga_target and Sga_max_size?
- What is difference between AMM and ASMM in Oracle?
- What is the shared pool in Oracle?
- What is library cache?
- How many buffers comprise a SGA?
- What is UGA memory?
- What is PGA aggregate limit?
- What is Java pool in Oracle?
- What is PGA in Oracle architecture?
- What is Oracle schedule?
- What is difference between PGA and UGA in Oracle?
- What is buffer cache in Oracle?
- What is Data Dictionary cache in Oracle?
- What is Oracle Smon?
- What is AMM and ASMM?
- What is shared memory in Oracle?
- What is automatic memory management?
- What is PGA aggregate target?
- What is the difference between Memory_target and Memory_max_target?
- What is SGA max size?
- What is memory target?
- How do I reduce the memory usage in Oracle?
- What is DB cache size?
What is difference between SGA and PGA?
1 Answer. The SGA is a memory structure on the server that contains pools to hold code, SQL, classes, cursors, etc. and caches to hold data. … The PGA is a shared memory area for a user server process and is used for temporary storage and work areas.
What is the purpose of SGA in Oracle?
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 automatic memory management in Oracle?
With automatic memory management, the Oracle instance dynamically tunes all memory components to optimize performance as the workload changes. To enable automatic memory management: Start SQL*Plus and connect to the database as SYSDBA .
Why PGA is used in Oracle?
A Program Global Area (PGA) is a memory region that contains data and control information for a server process. It is nonshared memory created by Oracle Database when a server process is started. Access to the PGA is exclusive to the server process. There is one PGA for each server process.
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What is large pool in Oracle?
The large pool is an optional memory area. It provides an area of memory from which large allocations can be made. Oracle’s backup and restore utilities typically allocate buffers that are hundreds of kilobytes in size. These will be allocated in the large pool if one is present.
What is UGA in Oracle?
User Session-Specific Data (UGA) Every connection to the Oracle database has a “session-specific” memory associated with it. This memory is referred to as the User Global Area (UGA) and is used to hold the values of PL/SQL variables, the values of bind variables and other items specific to a session.
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What is Sga_target and Sga_max_size?
*SGA_TARGET is actual memory in use by the current SGA. … SGA_MAX_SIZE sets the maximum value for sga_target. *SGA_TAGET is 10G feature used to change the sga size dynamically . it specifies the total amount of SGA memory available to an instance. This feature is called Automatic Shared Memory Management.
What is difference between AMM and ASMM in Oracle?
AMM in Oracle 11g: The 11g release uses AMM and manages all of the SGA AND PGA via the memory_target parameter. … ASMM in Oracle10g: Oracle ASMM was with Oracle 10g and uses two parameters sga_max_size for the SGA and pga_aggregate_target for the PGA.
What is the difference between Sga_target and Memory_target?
2 Answers. SGA_Target is the size of the SGA not including the PGA. Memory_Target includes both. If the PGA_target + SGA_Target are > Memory_Target, you can get this error.
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The shared pool is the area of the System Global Area (SGA) that contains structures such as the data dictionary cache and the shared SQL area. This is one of the most important storage structures in an Oracle database system.
What is library cache?
The Library Cache is a piece of memory within the SGA that Oracle uses in order to store SQL Statements. It is used to store shared SQL.
How many buffers comprise a SGA?
There must be at least 3 granules in the SGA: one for the Database Buffer Cache, one for the Shared Pool Area and one for the Redo Log Buffer.
What is UGA memory?
User Global Area (UGA) The UGA is memory associated with a user session. Software code areas. Software code areas are portions of memory used to store code that is being run or can be run.
What is PGA aggregate limit?
The actual PGA usage can be as high as three times of the value of PGA_AGGREGATE_TARGET. It will not terminate the session if usage exceeded. Excessive PGA usage can lead to memory swapping issue and have impact on the performance. PGA_AGGREGATE_LIMIT is a hard limit on the PGA memory usage.
What is Java pool in Oracle?
Answer: The java pool is a RAM region within the Oracle SGA and the java pool RAM is used to provide: Parsing of Java code and scripts. Installation tasks related to Java applications with Oracle 11g. Java stored procedure code parsing.
What is PGA in Oracle architecture?
Program global area (PGA) A PGA is a nonshared memory region that contains data and control information exclusively for use by an Oracle process. The PGA is created by Oracle Database when an Oracle process is started. One PGA exists for each server process and background process.
What is Oracle schedule?
Oracle Scheduler (the Scheduler) is implemented by the procedures and functions in the DBMS_SCHEDULER PL/SQL package. The Scheduler enables you to control when and where various computing tasks take place in the enterprise environment. The Scheduler helps you effectively manage and plan these tasks.
What is difference between PGA and UGA in Oracle?
The UGA normally comes from the SGA to allow migration of sessions across processes. If session migration is disabled, UGA memory will be allocated from the PGA. The Process Global Area (PGA) is memory which is physically private to a process (cannot be accessed by another process).
What is buffer cache in Oracle?
The buffer cache is the in-memory area of the SGA where incoming Oracle data blocks are kept. On standard Unix databases, the data is read from disk into the Unix buffer where it is then transferred into the Oracle buffer. The size of the buffer cache can have a huge impact on Oracle system performance.
What is Data Dictionary cache in Oracle?
As a key buffer cache of the shared pool, the data dictionary cache houses the internal data structures for the Oracle database. … Dictionary Cache is the memory areas designated to hold dictionary data. It is also known as the row cache because it holds data as rows instead of buffers (which hold entire blocks of data).
What is Oracle Smon?
The system monitor process (SMON) performs recovery, if necessary, at instance startup. SMON is also responsible for cleaning up temporary segments that are no longer in use and for coalescing contiguous free extents within dictionary managed tablespaces.
What is AMM and ASMM?
AMM (Automatic Memory Management) & ASMM (Automatic Shared MM) Posted by FatDBA on December 31, 2012. Evolution of Memory Management Features: Memory management has evolved with each database release: Oracle Database 10g.
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 is automatic memory management?
Automatic memory management (AMM) is a technique in which an operating system or application automatically manages the allocation and deallocation of memory. This means that a programmer does not have to write code to perform memory management tasks when developing an application.
What is PGA aggregate target?
PGA_AGGREGATE_TARGET specifies the target aggregate PGA memory available to all server processes attached to the instance. You must set this parameter to enable the automatic sizing of SQL working areas used by memory-intensive SQL operators such as sort, group-by, hash-join, bitmap merge, and bitmap create.
What is the difference between Memory_target and Memory_max_target?
As per my knowledge, memory_target is the parameter which oracle use to tune sga and pga components. and Memory_max_target is the parameter which is the max limit for the memory_target that can be tune dynamically by a dba.
What is SGA max size?
SGA_MAX_SIZE specifies the maximum size of the SGA for the lifetime of the instance. On 64-bit platforms and non-Windows 32-bit platforms, when either MEMORY_TARGET or MEMORY_MAX_TARGET is specified, the default value of SGA_MAX_SIZE is set to the larger of the two parameters.
What is memory target?
MEMORY_TARGET is a database initialization parameter (introduced in Oracle 11g) that can be used for automatic PGA and SGA memory sizing. … A single parameter for total SGA and PGA sizes.
How do I reduce the memory usage in Oracle?
- Execute from sqlplus show parameter target . …
- I had executed. …
- Updating ALTER SYSTEM SET memory_max_target = 10334765056 SCOPE=SPFILE; gives me the solution.
What is DB cache size?
DB_CACHE_SIZE specifies the size of the DEFAULT buffer pool for buffers with the primary block size (the block size defined by the DB_BLOCK_SIZE initialization parameter). The value must be at least 4M * number of cpus * granule size (smaller values are automatically rounded up to this value).
