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Oracle® Database Reference
12c Release 1 (12.1)

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DBA_HIST_DB_CACHE_ADVICE displays historical predictions of the number of physical reads for the cache size corresponding to each row. This view contains snapshots of V$DB_CACHE_ADVICE.

Column Datatype NULL Description
DBID NUMBER NOT NULL Database ID for the snapshot
INSTANCE_NUMBER NUMBER NOT NULL Instance number for the snapshot
BPID NUMBER NOT NULL Buffer Pool identifier (ranges from 1 to 8)
BUFFERS_FOR_ESTIMATE NUMBER NOT NULL Cache size for prediction (in terms of buffers)
NAME VARCHAR2(20)   Buffer pool name
BLOCK_SIZE NUMBER   Block size in bytes for buffers in the pool (the standard block size, the power of 2 nonstandard block sizes, 2048, 4096, 8192, 16384, or 32768)
ADVICE_STATUS VARCHAR2(3)   Status of the advisory:
  • ON - Currently running

  • OFF - Disabled (the estimates are historical and calculated when last enabled)

SIZE_FOR_ESTIMATE NUMBER   Cache size for prediction (in megabytes)
SIZE_FACTOR NUMBER   Size factor with respect to the current cache size
PHYSICAL_READS NUMBER   Physical reads for the cache size
BASE_PHYSICAL_READS NUMBER   Base physical reads for the cache size
ACTUAL_PHYSICAL_READS NUMBER   Actual physical reads for the cache size
ESTD_PHYSICAL_READ_TIME NUMBER   Estimated physical read time for the cache size
CON_DBID NUMBER   The database ID of the PDB for the sampled session
CON_ID NUMBER   The ID of the container that CON_DBID identifies. Possible values include:
  • 0: This value is used for rows containing data that pertain to the entire CDB. This value is also used for rows in non-CDBs.

  • 1: This value is used for rows containing data that pertain to only the root

  • n: Where n is the applicable container ID for the rows containing data