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Donald K. Burleson
Oracle Tips |
Oracle PGA
OPEN_LINKS. The number of database
links allowed open per user.
DB_FILES. The number of database files allowed for the database (up
to the value of MAX_DATAFILES).
LOG_FILES. The maximum number of redo log file groups (up to the
value of MAX_LOGFILES).
The PGA also contains session-related information if MTS is not
used. In environments where MTS is used, the session information is
placed in the SHARED_POOL region of the SGA if the LARGE POOL (in
Oracle8,8i and 9i) is not configured. This session information
consists of the user’s private SQL area and other session-specific
data. The PGA will always hold the user’s stack information. The
section of the shared or LARGE POOL allocated for the user is called
the UGA, which stands for Users Global Area.
Another contributor to the memory footprint of each process is the
size of the SORT_AREA_SIZE and SORT_AREA_RETAINED_SIZE parameters.
When a process executes a sort memory, the size of SORT_AREA_SIZE is
allocated to the user. If SORT_AREA_RETAINED_SIZE is also set, then
this amount of memory is reduced to that value and allowed to grow
to SORT_AREA_SIZE. If the sort requires more space than is specified
in SORT_AREA_SIZE, the sort is broken into SORT_AREA_SIZED chunks,
which are swapped out to disk as needed.
Some System-Specific Notes
Each specific operating system contains certain items that a DBA
needs to be aware of and take into account when installing Oracle.
This section attempts to consolidate these system-specific notes in
one location.
This is an
excerpt by Mike Ault’s book “Oracle
Administration & Management”. If you want more current Oracle tips
by Mike Ault, check out his new book “Mike
Ault’s Oracle Internals Monitoring & Tuning Scripts” or
Ault’s Oracle Scripts Download.
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