Different States of Capture & Apply Process [ID 471713.1]

Posted: 九月 15, 2011 in oracle, oracle document notes


Modified 14-DEC-2010 Type
BULLETIN Status PUBLISHED

In this Document

Purpose

Scope and Application

Different States of Capture & Apply Process

References


Applies to:

Oracle Server – Enterprise Edition – Version: 9.2.0.1
to 11.2.0.2.0 – Release: 9.2 to 11.2

Information in this document applies to any platform.

***Checked for relevance on 14-DEC-2010***

Purpose

The purpose of this is to provide a better
understanding of different states of the streams capture & apply process.

Scope and Application

Applicable for all platforms.

Different States of Capture & Apply Process

NOTE : There are some additional process states, which is not visible using the
specific views, because such states comes for fraction of second and are
internal.

Capture Process States :

The state of a capture process describes what the
capture process is doing currently. You can view the state of a capture
process by querying the STATE column in the V$STREAMS_CAPTURE dynamic
performance view.

The following capture process states are possible in
Oracle 9.2:

* INITIALIZING – Starting up.

* CAPTURING CHANGES – Scanning the redo log for
changes that evaluate to TRUE against the capture process rule sets.

* EVALUATING RULE – Evaluating a change against a
capture process rule set.

* CREATING LCR – Converting a change into an LCR.

* ENQUEUING MESSAGE – Enqueuing an LCR that
satisfies the capture process rule sets into the capture process queue.

* SHUTTING DOWN – Stopping.

The following capture process states are possible in
Oracle 10g and 11.1:

* In addition to the above Capture Process States
the below are the states introduced in oracle 10g and above version.

* WAITING FOR DICTIONARY REDO – Waiting for redo log
files containing the dictionary build related to the first SCN to be added to
the capture process session. A capture process cannot begin to scan the redo
log files until all of the log files containing the dictionary build have
been added.

* DICTIONARY INITIALIZATION – Processing a dictionary build.

* MINING (PROCESSED SCN = scn_value) – Mining a dictionary build at the SCN
scn_value.

* LOADING (step X of Y) – Processing information from a dictionary build and
currently at step X in a process that involves Y steps, where X and Y are
numbers.

* WAITING FOR REDO – Waiting for new redo log files to be added to the
capture process session. The capture process has finished processing all of
the redo log files added to its session. This state is possible if there is
no activity at a source database. For a downstream capture process, this
state is possible if the capture process is waiting for new log files to be
added to its session.

* PAUSED FOR FLOW CONTROL – Introduced in Oracle 10g. Prior to Oracle 9i we
need to configure Flow Control explicitly. It Unable to enqueue LCRs either
because of low memory or because propagations and apply processes are
consuming messages slower than the capture process is creating them. This
state indicates flow control that is used to reduce spilling of captured
messages when propagation or apply has fallen behind or is unavailable.

The following capture process states are possible in
Oracle 11gR2.

In addition to the above Capture Process States the
below are the states introduced in oracle 11gR2 .

* WAITING FOR A SUBSCRIBER TO BE ADDED – Waiting for
a subscriber to the capture process’s queue to be added. A subscriber can be
a propagation or an apply process.

* WAITING FOR THE BUFFERED QUEUE TO SHRINK – Waiting for the buffered queue
to change to a smaller size. The buffered queue shrinks when there is a
memory limitation or when an administrator reduces its size.

* WAITING FOR n SUBSCRIBER(S) INITIALIZING – Waiting
for apply processes that receive LCRs from the capture process to start,
where n is the number of apply processes.

* WAITING FOR TRANSACTION – Waiting for LogMiner to provide more
transactions.

* WAITING FOR INACTIVE DEQUEUERS – Waiting for capture process’s queue
subscribers to start. The capture process stops enqueuing LCRs if there are
no active subscribers to the queue.

* SUSPENDED FOR AUTO SPLIT/MERGE – Waiting for a merge operation to complete.

* SHUTTING DOWN – Stopping.

* ABORTING – Aborting

Apply Server States :

The state of an apply server describes what the apply server is doing
currently. You can view the state of each apply server for an apply process
by querying the V$STREAMS_APPLY_SERVER dynamic performance view. The
following apply server states are possible:

The following apply process states are possible in
Oracle 9.2:

* IDLE – Performing no work.

* RECORD LOW-WATERMARK – Performing an
administrative action that maintains information about the apply progress,
which is used in the ALL_APPLY_PROGRESS and DBA_APPLY_PROGRESS data
dictionary views.

*ADD PARTITION – Performing an administrative action
that adds a partition that is used for recording information about
in-progress transactions.

* DROP PARTITION – Performing an administrative
action that drops a partition that was used to record information about
in-progress transactions.

* EXECUTE TRANSACTION – Applying a transaction.

* WAIT COMMIT – Waiting to commit a transaction
until all other transactions with a lower commit SCN are applied. This state
is possible only if the COMMIT_SERIALIZATION apply process parameter is set
to a value other than none and the PARALELLISM apply process parameter is set
to a value greater than 1.

* WAIT DEPENDENCY – Waiting to apply an LCR in a
transaction until another transaction, on which it has a dependency, is
applied. This state is possible only if the PARALELLISM apply process
parameter is set to a value greater than 1.

* WAIT FOR NEXT CHUNK – Waiting for the next set of
LCRs for a large transaction.

The following apply process states are possible in
Oracle 10g and above:

* In addition to the above Capture Process States the below are the states
introduced in oracle 10g and above version.

* TRANSACTION CLEANUP – Cleaning up an applied
transaction, which includes removing LCRs from the apply process queue.

* INITIALIZING – Starting up.

The following apply process states are possible in
Oracle 11gR2:

ROLLBACK TRANSACTION – Rolling back a transaction.

Apply Reader States :

The state of a reader server describes what the reader server is doing currently.
You can view the state of the reader server for an apply process by querying
the V$STREAMS_APPLY_READER dynamic performance view. The following reader
server states are possible:

The following apply process states are possible in
Oracle 9.2:

* IDLE – Performing no work

* DEQUEUE MESSAGES – Dequeuing messages from the
apply process queue

* SCHEDULE MESSAGES – Computing dependencies between
messages and assembling messages into transactions

The following apply process states are possible in
Oracle 10g and above:

* In addition to the above Capture Process States the below are the states
introduced in oracle 10g and above version.

* INITIALIZING – Starting up

* SPILLING – Spilling unapplied messages from memory
to hard disk

* PAUSED – Waiting for a DDL LCR to be applied

Apply Coordinator States :

The state of a coordinator process describes what the coordinator process is
doing currently. You can view the state of a coordinator process by querying
the V$STREAMS_APPLY_COORDINATOR dynamic performance view. The following
coordinator process states are possible:

The following apply process states are possible in
Oracle 9.2 and above:

* INITIALIZING – Starting up

* APPLYING – Passing transactions to apply servers

* SHUTTING DOWN CLEANLY – Stopping without an error

* ABORTING – Stopping because of an apply error

Reference :

Oracle� Streams Concepts and
Administration

11g Release 1 (11.1) Part Number B28321-02

10g Release 2 (10.2) Part Number B14229-04

10g Release 1 (10.1) Part Number B10727-01

Oracle9i Streams

Release 2 (9.2) Part Number A96571-02

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