The PGA is used to process SQL statements and to hold logon and other session information. A large part of the PGA is dedicated to SQL work areas, which are working memory areas for sorts and other SQL operations.

What is the purpose of PGA memory?

The Program Global Area (PGA) is a private memory region that contains the data and control information for a server process. Only a server process can access the PGA. Oracle Database reads and writes information in the PGA on behalf of the server process.

What is the difference between SGA and PGA in Oracle?

The SGA is a group of shared memory structures, known as SGA components, that contain data and control information for one Oracle Database instance. ... A PGA is a nonshared memory region that contains data and control information exclusively for use by an Oracle process.

What is PGA and UGA in Oracle?

they are oracle memory regions. pga is PROCESS global area, it is in dedicated and shared servers (never in the SGA) the uga is USER global area, it is session memory and it is in the PGA when using dedicated server, in the SGA when using shared server.

What is Session PGA memory in Oracle?

The session pga memory Oracle metric statistic shows the current PGA size for a session. This statistic is useful only in V$SESSTAT; it has no meaning in V$SYSSTAT. You can increase the available PGA allocation about its 5% limit to provide extra PGA RAM for very large sorting and hash joins.

What is PGA? - Oracle SQL Tutorial

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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 PGA aggregate target?

PGA_AGGREGATE_TARGET specifies the target aggregate PGA memory available to all server processes attached to the instance. Setting PGA_AGGREGATE_TARGET to a nonzero value has the effect of automatically setting the WORKAREA_SIZE_POLICY parameter to AUTO .

What is UGA in Oracle database?

The UGA is session memory, which is memory allocated for session variables, such as logon information, and other information required by a database session. Essentially, the UGA stores the session state.

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 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.

Is PGA part of SGA?

pga is private, is it not allocated from the SGA at all.

What is library cache in Oracle?

Oracle's library cache is nothing more than an area in memory, specifically one of three parts inside the shared pool. The library cache is composed of shared SQL areas, PL/SQL packages and procedures, various locks & handles, and in the case of a shared server configuration, stores private SQL areas.

What means PGA?

or P.G.A. abbreviation. Professional Golfers' Association.

What is PGA aggregate limit?

If a value of 0 is specified, it means there is no limit to the aggregate PGA memory consumed by the instance. PGA_AGGREGATE_LIMIT specifies a limit on the aggregate PGA memory consumed by the instance. There is no difference in behavior between PGA_AGGREGATE_LIMIT being explicitly set or being set to the default.

What are the contents of PGA?

The two components of the PGA

When you execute an SQL statement, the source and the execution plan are stored in shared memory because all processes can use that information. Information that is process specific, such as bind variable information and PL/SQL variable values, is contained in the PGA.

What is SGA memory 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 Data Dictionary cache in Oracle?

Dictionary Cache

The data dictionary is accessed so often by Oracle that two special locations in memory are designated to hold dictionary data. One area is called the data dictionary cache, also known as the row cache because it holds data as rows instead of buffers (which hold entire blocks of data).

What is result cache in Oracle?

A result cache is an area of memory, either in the Shared Global Area (SGA) or client application memory, that stores the results of a database query or query block for reuse. The cached rows are shared across SQL statements and sessions unless they become stale.

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.

How does Oracle determine SGA and PGA size?

The Oracle DBA can use math to determine the optimal RAM allocation for a MS-Windows server.
...
The total RAM SGA and PGA estimates for Oracle are as follows:

1. OS RAM : 20 percent of total RAM for MS-Windows, 10% of RAM for UNIX.
2. Oracle SGA RAM : determined with the show sga command.

What is session UGA memory?

The session uga memory Oracle metric statistic shows the current UGA size for a session. ... Each dedicated session connected to Oracle gets a portion of the PGA and this is the UGA memory. The UGA is memory allocated to hold a stock of user-detailed information, such as program variables, sorting and hash joins.

What is difference between SGA_Target and Memory_Target Oracle?

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.

How do I change the PGA size in Oracle?

You change the PGA Aggregate maximum size by setting a parameter called PGA Aggregate Target. Note: Oracle Database XE always allocates the full amount of memory specified by the SGA Target parameter. That is, the current SGA size is always equal to SGA Target.

What is the difference between PGA aggregate limit and Pga_aggregate_target?

PGA_AGGREGATE_TARGET is the parameter for control PGA memory allocation. 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.