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Oracle® Database Reference
11g Release 2 (11.2)

E40402-12
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V$STREAMS_APPLY_READER

V$STREAMS_APPLY_READER displays information about each apply reader. The apply reader is a process which reads (dequeues) messages from the queue, computes message dependencies, and builds transactions. It passes the transactions on to the coordinator in commit order for assignment to the apply servers. An apply reader is a subcomponent of an apply process, outbound server, or inbound server.

Column Datatype Description
SID NUMBER Session ID of the reader's session
SERIAL# NUMBER Serial number of the reader's session
APPLY# NUMBER Apply process number. An apply process is an Oracle background process, prefixed by ap.
APPLY_NAME VARCHAR2(30) Name of the apply process
STATE VARCHAR2(36) State of the reader:
  • INITIALIZING - Starting up

  • IDLE - Performing no work

  • DEQUEUE MESSAGES - Dequeuing messages from the queue

  • SCHEDULE MESSAGES - Computing dependencies between messages and assembling messages into transactions

  • SPILLING - Spilling unapplied messages from memory to hard disk

  • PAUSED - WAITING FOR DDL TO COMPLETE - Waiting for a DDL LCR to be applied

TOTAL_MESSAGES_DEQUEUED NUMBER Total number of messages dequeued since the apply process was last started
TOTAL_MESSAGES_SPILLED NUMBER Number of messages spilled by the reader since the apply process was last started
DEQUEUE_TIME DATE Time when the last message was received
DEQUEUED_MESSAGE_NUMBER NUMBER Number of the last message received
DEQUEUED_MESSAGE_CREATE_TIME DATE For captured messages, creation time at the source database of the last message received. For user-enqueued messages, time when the message was enqueued into the queue at the local database.
SGA_USED NUMBER Amount (in bytes) of SGA memory used by the apply process since it was last started
ELAPSED_DEQUEUE_TIME NUMBER Time elapsed (in hundredths of a second) dequeuing messages since the apply process was last started
ELAPSED_SCHEDULE_TIME NUMBER Time elapsed (in hundredths of a second) scheduling messages since the apply process was last started. Scheduling includes computing dependencies between messages and assembling messages into transactions.
ELAPSED_SPILL_TIME NUMBER Elapsed time (in hundredths of a second) spent spilling messages since the apply process was last started
LAST_BROWSE_NUM NUMBER Reserved for internal use
OLDEST_SCN_NUM NUMBER Oldest SCN
LAST_BROWSE_SEQ NUMBER Reserved for internal use
LAST_DEQ_SEQ NUMBER Last dequeue sequence number
OLDEST_XIDUSN NUMBER Transaction ID undo segment number of the oldest transaction that either has been applied or is being applied
OLDEST_XIDSLT NUMBER Transaction ID slot number of the oldest transaction that either has been applied or is being applied
OLDEST_XIDSQN NUMBER Transaction ID sequence number of the oldest transaction that either has been applied or is being applied
SPILL_LWM_SCN NUMBER Spill low-watermark SCN
PROXY_SID NUMBER When the apply process uses combined capture and apply, the session ID of the propagation receiver that is responsible for direct communication between capture and apply. If the apply process does not use combined capture and apply, then this column is 0.
PROXY_SERIAL NUMBER When the apply process uses combined capture and apply, the serial number of the propagation receiver that is responsible for direct communication between capture and apply. If the apply process does not use combined capture and apply, then this column is 0.
PROXY_SPID VARCHAR2(12) When the apply process uses combined capture and apply, the process identification number of the propagation receiver that is responsible for direct communication between capture and apply. If the apply process does not use combined capture and apply, then this column is 0.
CAPTURE_BYTES_RECEIVED NUMBER When the apply process uses combined capture and apply, the number of bytes received by the apply process from the capture process since the apply process last started. If the apply process does not use combined capture and apply, then this column is not populated.
DEQUEUED_POSITION RAW(64) Dequeued position

This column is populated only for an apply process that is functioning as an XStream inbound server.

LAST_BROWSE_POSITION RAW(64) Reserved for internal use
OLDEST_POSITION RAW(64) The earliest position of the transactions currently being dequeued and applied

This column is populated only for an apply process that is functioning as an XStream inbound server.

SPILL_LWM_POSITION RAW(64) Spill low-watermark position

This column is populated only for an apply process that is functioning as an XStream inbound server.

OLDEST_TRANSACTION_ID VARCHAR2(128) Oldest transaction ID
TOTAL_LCRS_WITH_DEPFoot 1  NUMBER Total number of LCRs with row-level dependencies since the apply process last started
TOTAL_LCRS_WITH_WMDEPFootref 1 NUMBER Total number of LCRs with watermark dependencies since the apply process last started

A watermark dependency occurs when an apply process must wait until the apply process's low watermark reaches a particular threshold.

TOTAL_IN_MEMORY_LCRSFootref 1 NUMBER Total number of LCRs currently in memory
SGA_ALLOCATEDFootref 1 NUMBER The total amount of shared memory (in bytes) allocated from the Streams pool for the apply process since the apply process last started

Footnote 1 This column is available starting with Oracle Database 11g Release 2 (11.2.0.2).

Note:

The ELAPSED_DEQUEUE_TIME and ELAPSED_SCHEDULE_TIME columns are only populated if the TIMED_STATISTICS initialization parameter is set to true, or if the STATISTICS_LEVEL initialization parameter is set to TYPICAL or ALL.