Tuning the Database - Expert Oracle RAC Performance Diagnostics and Tuning - page 299

[Memory]
Total Memory = 208144 bytes [0.004% of the Shared Pool]
... Fixed Memory = 13928 bytes [0.000% of the Shared Pool]
....... Memory Mgr = 200 bytes
....... Bloom Fltr = 2K bytes
....... = 3232 bytes
....... Cache Mgr = 5552 bytes
....... State Objs = 2896 bytes
... Dynamic Memory = 194216 bytes [0.004% of the Shared Pool]
....... Overhead = 161448 bytes
........... Hash Table = 64K bytes (4K buckets)
........... Chunk Ptrs = 62920 bytes (7865 slots)
........... Chunk Maps = 31460 bytes
........... Miscellaneous = 1532 bytes
....... Cache Memory = 32K bytes (32 blocks)
........... Unused Memory = 23 blocks
........... Used Memory = 9 blocks
............... Dependencies = 2 blocks (2 count)
............... Results = 7 blocks
................... SQL = 7 blocks (1 count)

PL/SQL procedure successfully completed.
One execution of the query on instance 3 gives an identical memory structure to that on instance 1; .004% of the
dynamic memory section has been allocated to the result cache section to store 9 blocks of data.

Step 8
Querying the GV$RESULT_CACHE_OBJECTS view, there are two result cache sections, one on instance 1 and another on
instance 2, indicating that in an Oracle RAC environment, Oracle Database does not maintain a global result cache
section. Rather, it manages the result cache locally on the respective instances.

Script: MVRACPDnTap_rcobjects.sql

There are several factors to observe in the preceding output:

CACHE_ID on both instances. • The query has the same

• From the execution plan (Step 4), you observed that the number of rows in the result cache of

instance 3 is identical to instance 1.