What is SGA and PGA in Oracle?

What is 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 Sga_target & Sga_max_size?

*SGA_TARGET is actual memory in use by the current SGA. This parameter is dynamic and can be increased up to the value of SGA_MAX_SIZE. SGA_MAX_SIZE and SGA_TARGET both are the parameter are used to change the SGA SIZE. *The SGA_MAX_SIZE parameter is the max allowable size to resize the SGA Memory area parameters.

What is PGA memory used for?

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 automatic memory tuning?

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 percentage of RAM should Oracle SGA be set?

The total RAM demands for Oracle on MS-Windows are as follows: OS RAM 20 percent of total RAM for MS-Windows, 10% of RAM for UNIX. Oracle SGA RAM determined with the show sga command.

How do I know my PGA size?

You can check your overall PGA usage with the v$pga_target_advice advisory utility or a STATSPACK or AWR report.

What is the difference between SGA_Target and Memory_target?

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.

Why do we create pfile from Spfile?

A PFILE is a traditional text based init. ora parameter file. Typically this resides on the server in the $ORACLE_BASE/admin/SID/pfile directory, with a symbolic link pointing to it from the $ORACLE_HOME/dbs directory. A PFILE is necessary in order to create a SPFILE to enable persistent initialization parameters.

What is Session PGA memory?

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 used to logically group data together?

A tablespace is used to logically group data together.

How do I know if my automatic memory management is enabled?

To enable automatic memory management: Start SQL*Plus and connect to the database as SYSDBA . SQL*Plus displays the values of all initialization parameters with the string TARGET in the parameter name.

What is difference between SGA_Target and Memory_target Oracle?