SNAP_ID

NUMBER

NOT NULL

Unique snapshot ID

DBID

NUMBER

NOT NULL

Database ID for the snapshot

INSTANCE_NUMBER

NUMBER

NOT NULL

Instance number for the snapshot

CR_REQUESTS

NUMBER

Number of CR blocks served due to remote CR block requests

CURRENT_REQUESTS

NUMBER

Number of current blocks served due to remote CR block requests

CR_REQUESTS + CURRENT_REQUESTS = global cache CR blocks served (from V$SYSSTAT).

DATA_REQUESTS

NUMBER

Number of current or CR requests for data blocks

UNDO_REQUESTS

NUMBER

Number of CR requests for undo blocks

TX_REQUESTS

NUMBER

Number of CR requests for undo segment header blocks

DATA_REQUESTS + UNDO_REQUESTS + TX_REQUESTS = total number of requests handled by the LMS processes

CURRENT_RESULTS

NUMBER

Number of requests for which no changes were rolled out of the block returned to the requesting instance

PRIVATE_RESULTS

NUMBER

Number of requests for which changes were rolled out of the block returned to the requesting instance, and only the requesting transaction can use the resulting CR block

ZERO_RESULTS

NUMBER

Number of requests for which changes were rolled out of the block returned to the requesting instance. Only zero-XID transactions can use the block.

DISK_READ_RESULTS

NUMBER

Number of requests for which the requesting instance had to read the requested block from disk

FAIL_RESULTS

NUMBER

Number of requests that failed; the requesting transaction must reissue the request

FAIRNESS_DOWN_CONVERTS

NUMBER

Number of times an instance receiving a request has down-converted an X lock on a block because it was not modifying the block

FLUSHES

NUMBER

Number of times the log has been flushed by an LMS process

FLUSHES

NUMBER

Number of times the log has been flushed by an LMS process

BUILDS

NUMBER

Number of requests for which the server had to fabricate a CR block

This column is available starting with Oracle Database 12c Release 2 (12.2.0.1).

LIGHT_WORKS

NUMBER

Number of times the light-work rule was evoked. This rule prevents the LMS processes from going to disk while responding to CR requests for data, undo, or undo segment header blocks. This rule can prevent the LMS process from completing its response to the CR request.

ERRORS

NUMBER

Number of times an error was signalled by an LMS process

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