8.202 V$EQ_MESSAGE_CACHE_ADVICE

V$EQ_MESSAGE_CACHE_ADVICE shows simulated metrics for a range of potential message cache sizes for Transactional Event Queues (TEQs). This view assists in cache sizing by providing information in the form of metrics as described below.

Column Datatype Description

SIZE_FOR_ESTIMATE

NUMBER

Cache size for simulation (in megabytes)

SIZE_FACTOR

NUMBER

Size factor with respect to the current cache size

ESTD_SIZE_TYPE

VARCHAR2(9)

Possible values:

  • MINIMUM: This cache size is required to have all dequeues in-memory (no uncached).

  • CURRENT: This is the current size of the message cache.

  • MAXIMUM: This cache size is required to have zero evictions.

  • NULL: This is the value in all other cases.

ESTD_CACHED_PARTITIONS

NUMBER

Estimated number of cached event stream partitions for this size

ESTD_UNCACHED_PARTITIONS

NUMBER

Estimated number of uncached event stream partitions for this size

ESTD_EVICTIONS

NUMBER

Estimated number of event stream partitions evicted for this size

ESTD_EVICTION_RATE

NUMBER

Estimated number of event stream partitions getting evicted per minute

ESTD_FG_UNEVICTIONS

NUMBER

Estimated number of event stream partitions unevicted by foreground processes

ESTD_FG_UNEVICTION_RATE

NUMBER

Estimated number of event stream partitions getting unevicted by foreground processes

ESTD_BG_UNEVICTIONS

NUMBER

Estimated number of event stream partitions unevicted by background processes

ESTD_BG_UNEVICTION_RATE

NUMBER

Estimated number of event stream partitions getting unevicted by background processes

ESTD_BG_PROCESSES

NUMBER

Estimated number of background processes required for this size

TOTAL_ENQUEUE_RATE

NUMBER

Simulated number of messages being enqueued per second

TOTAL_DEQUEUE_RATE

NUMBER

Simulated number of messages being dequeued per second

AVG_PARTITION_SIZE

NUMBER

Simulated average number of messages per cached event stream partitions

AVG_PARTITION_MEMORY

NUMBER

Simulated average memory per cached event stream partition (in megabytes)

AVG_EVICTION_TIME

NUMBER

Simulated average time to evict a cached event stream partition (in milliseconds)

AVG_UNEVICTION_TIME

NUMBER

Simulated average time to unevict a cached event stream partition (in milliseconds)

FLAGS

NUMBER

Reserved for internal use

SIMULATION_TIME

NUMBER

Amount of time that was simulated for (in minutes)

CON_ID

NUMBER

The ID of the container to which the data pertains. 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

Note:

This view is available starting with Oracle Database 21c.

See Also:

Oracle Database Advanced Queuing User's Guide for more information about Oracle Transactional Event Queues and Advanced Queuing