文档介绍：深入解析Cursor和绑定变量
崔华(dbsnake)
About Me
•中航信工程师
•云和恩墨特邀顾问
• Oracle ACE
• ACOUG成员
Cursors in Oracle
• sharable sql structure / shared cursor
This is the object that lives in the shared pool and whose
metadata is exposed in the v$sqlarea and v$sql views
Shared Cursor Information
The shared pool maintains sharable parts of the cursor in
the library cache, including:
• SQL text
• Parse tree
• Object definitions
• Execution plan
• Bind variable data types and lengths
Shared Cursor Lookup
Library Cache Latches
• The library cache latches serialize access to the objects
in the library cache. Access to library cache objects
always occurs through locks (enqueues). Because
locking an object is not an atomic instruction, a library
cache latch is acquired before the lock request and is
released after it. For most operations, the library cache
latches are used, and therefore they can e a point
of contention.