4031 obfuscation

Some memory jargon :

  • free-lists
  • buckets
  • chunks
  • heap
  • subheap
  • bucket
  • lru
    searching all the free lists,
    aging all objects possible from the LRU list,
    and
    scanning the free list multiple times.

What is important is
the size of the largest chunk that can be freed
or
merged after some LRU operations.
‘library cache’, ‘KGLS heap’, ‘CCursor’.

subpool size
9i = 128mb
10g = 256mb

there can be 1 subpool for every 4 CPU (max to 7 subpools)

12 cpu
300MB

3 subpools
2

b1 := 20
select ename from emp where empno = :b1

b1 := 30
select ename from emp where empno = :b1
Large Pool
offload larger memory allocations from the Shared Pool related to
– Shared Server (UGA)
– Parallel Processing (Buffer allocations)
– RMAN backup operations
– Sequential file IO (e.g. IO slave activity)

Reasons for 4031

  • Lack of PreparedStatement
  • Fragmentation
  • KGH : NO ACCESS (or frequent dynamic memory resizing in SGA_TARGET)
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