SGA Re-Sizes Occurring Despite AMM/ASMM Being Disabled (MEMORY_TARGET/SGA_TARGET=0)
(Doc ID 1269139.1)
Last updated on MARCH 18, 2025
Applies to:
Oracle Database Cloud Exadata Service - Version N/A and laterOracle Database Backup Service - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Cloud Service - Version N/A and later
Oracle Database - Enterprise Edition - Version 11.2.0.1 and later
Information in this document applies to any platform.
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.:
---------------------- ---------- --------- ----------------- ------------ ----------- ---------- --------- -------------------- --------------------
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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In this Document
| Symptoms |
| Changes |
| Cause |
| Solution |
| References |