SGA Re-Sizes Occurring Despite AMM/ASMM Being Disabled (MEMORY_TARGET/SGA_TARGET=0) (Doc ID 1269139.1)

Last updated on AUGUST 22, 2016

Applies to:

Oracle Database - Enterprise Edition - Version 11.2.0.1 and later
Oracle Database - Standard Edition - Version 11.2.0.3 to 11.2.0.3 [Release 11.2]
Information in this document applies to any platform.
***Checked for relevance on 02-Nov-2015***

Symptoms

SGA re-sizes are occurring after upgrade to 11.2 despite the fact that automatic memory management (AMM/ASMM) is disabled via the MEMORY_TARGET and SGA_TARGET parameters being set to zero.  This typically appears as growth in the __SHARED_POOL_SIZE value and a reduction in the __DB_CACHE_SIZE value being used in the instance, such that __DB_CACHE_SIZE may be shrunk below the DB_CACHE_SIZE value specified in the init.ora/spfile.

Checking V$MEMORY_RESIZE_OPS / V$SGA_RESIZE_OPS shows an IMMEDIATE re-size having occurred, e.g.:

COMPONENT              OPER_TYPE  OPER_MODE PARAMETER         INITIAL_SIZE TARGET_SIZE FINAL_SIZE STATUS    START_TIME           END_TIME
---------------------- ---------- --------- ----------------- ------------ ----------- ---------- --------- -------------------- --------------------
DEFAULT buffer cache   SHRINK     IMMEDIATE db_cache_size     7.4357E+10   7.4088E+10  7.4088E+10  COMPLETE 12-OCT-2010 14:26:51 12-OCT-2010 14:26:51
shared pool            GROW       IMMEDIATE shared_pool_size  2684354560   2952790016  2952790016  COMPLETE 12-OCT-2010 14:26:51 12-OCT-2010 14:26:51

 

Changes

The database has been upgraded to 11.2.

Cause

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