Books for you

180 | Chapter 7: Oracle Performance
The PGA consists of a working memory area for things such as temporary variables
used by the server process, memory for information about the SQL the server process
is executing, and memory for sorting rows as part of SQL execution. The initial
size of the PGA??™s working memory area for variables, known as stack space, cannot
be directly controlled because it??™s predetermined based on the operating system you
are using for your database server. The other areas within the PGA can be controlled
as described in the following sections.
Memory for SQL statements
When a server process executes a SQL statement for a user, the server process tracks
the session-specific details about the SQL statement and the progress by executing it
in a piece of memory in the PGA called a private SQL area, also known as a cursor.
This area should not be confused with the shared SQL area within the shared pool.
The shared SQL area contains shareable details for the SQL statement, such as the
optimization plan.


Pages:
378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402