| Oracle® Streams Concepts and Administration 11g Release 2 (11.2) Part Number E17069-05 |
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PDF · Mobi · ePub |
| Oracle® Streams Concepts and Administration 11g Release 2 (11.2) Part Number E17069-05 |
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PDF · Mobi · ePub |
Optional information associated with a rule that is interpreted by the client of the rules engine when the rule is evaluated for a message.
A queue of type ANYDATA. These queues can stage messages of different types wrapped in an ANYDATA wrapper.
See Also: typed queue
A system change number (SCN) relating to a capture process that corresponds to the most recent message dequeued by an apply process that applies changes captured by the capture process.
A directed network in which messages being forwarded at an intermediate database are first processed by an apply process. These messages are then recaptured by a capture process at the intermediate database and forwarded.
See Also: queue forwarding
A collection of SQL statements or a user-defined procedure used by an apply process for customized processing of messages. Apply handlers include statement DML handlers, message handlers, procedure DML handlers, DDL handlers, precommit handlers, and error handlers.
An optional Oracle background process that dequeues messages from a specific queue and either applies each message directly, discards it, passes it as a parameter to an apply handler, or re-enqueues it. An apply process is an Oracle Streams client.
See Also: logical change record (LCR)
A component of an apply process that includes one or more processes that apply LCRs to database objects as DML or DDL statements or pass the LCRs to their appropriate apply handlers. For user messages, the apply servers pass the messages to the message handler. Apply servers can also enqueue logical change record (LCR) and non-LCR messages specified by the DBMS_APPLY_ADM.SET_ENQUEUE_DESTINATION procedure. If an apply server encounters an error, then it tries to resolve the error with a user-specified error handler. If an apply server cannot resolve an error, then it places the entire transaction, including all of its LCRs, in the error queue.
See Also: logical change record (LCR)
The user in whose security domain an apply process dequeues messages that satisfy its rule sets, applies messages directly to database objects, runs custom rule-based transformations configured for apply process rules, and runs apply handlers configured for the apply process.
approximate commit system change number (approximate CSCN)
An SCN value based on the current SCN of the database when a transaction that has enqueued messages into a commit-time queue is committed.
archived-log downstream capture process
A downstream capture process that captures changes in archived redo log files copied from the source database to the downstream database.
A DDL transaction or a transaction that includes a row logical change record (row LCR) for which an apply process cannot identify the table rows or the database object by using the destination database data dictionary and virtual dependency definitions.
A logical change record (LCR) that is constructed explicitly by an application and enqueued into the buffered queue portion of an ANYDATA queue.
The portion of a queue that uses the Oracle Streams pool to store messages in memory and a queue table to store messages that have spilled from memory.
A non-LCR message of a user-defined type that is created explicitly by an application and enqueued into a buffered queue. A buffered user message can be enqueued into the buffered queue portion of an ANYDATA queue or a typed queue.
A component of a capture process that is a process that merges redo records from the preparer server. These redo records either evaluated to TRUE during partial evaluation or partial evaluation was inconclusive for them. The builder server preserves the system change number (SCN) order of these redo records and passes the merged redo records to the capture process.
The database running the capture process that captures changes made to the source database. The capture database and the source database are the same database when the capture process is a local capture process. The capture database and the source database are different when the capture process is a downstream capture process.
An optional Oracle background process that scans the database redo log to capture DML and DDL changes made to database objects. A capture process is an Oracle Streams client.
Either the user in whose security domain a capture process captures changes that satisfy its rule sets and runs custom rule-based transformations configured for capture process rules, or the user in whose security domain a synchronous capture captures changes that satisfy its rule set and runs custom rule-based transformations configured for synchronous capture rules.
A logical change record (LCR) that was captured implicitly by a capture process and enqueued into the buffered queue portion of an ANYDATA queue.
See Also: user message
The system change number (SCN) that corresponds to the most recent change scanned in the redo log by a capture process.
Sending a change back to the database where it originated. Typically, change cycling should be avoided in an information sharing environment by using tags and by using the LCR member function GET_SOURCE_DATABASE_NAME in rule conditions.
See Also: logical change record (LCR)
A special type of statement DML handler that tracks table changes and was created by either the DBMS_STREAMS_ADM.MAINTAIN_CHANGE_TABLE procedure or the DBMS_APPLY_ADM.SET_CHANGE_HANDLER procedure.
Information about the current state of a capture process that is stored persistently in the data dictionary of the database running the capture process.
A regular interval at which a capture process attempts to record a checkpoint.
The amount of time that a capture process retains checkpoints before purging them automatically.
A list of columns for which an update conflict handler is called when an update conflict occurs for one or more of the columns in the list.
See Also: conflict resolution
A queue in which messages are ordered by their approximate commit system change number (approximate CSCN) values.
A supplemental log group that logs the before images of all specified columns only if at least one of the columns in the supplemental log group is modified.
See Also: unconditional log group
A mismatch between the old values in an LCR and the expected data in a table. Conflicts are detected by an apply process when it attempts to apply an LCR. Conflicts typically result when two different databases that are sharing data in a table modify the same row in the table at nearly the same time.
See Also: logical change record (LCR)
Handling a conflict to avoid an apply error. Either prebuilt update conflict handlers or custom conflict handlers can resolve conflicts.
A component of an apply process that is an Oracle background process that gets transactions from the reader server and passes them to apply servers.
An apply process passes an LCR as a parameter to a user procedure for processing. The user procedure can process the LCR in a customized way.
See Also: logical change record (LCR)
custom rule-based transformation
A rule-based transformation that requires a user-defined PL/SQL function to perform the transformation.
See Also: declarative rule-based transformation
The type of supplemental logging that can apply to the primary key, foreign key, and unique key columns in an entire database.
An apply handler that uses a PL/SQL procedure to process DDL LCRs.
See Also: DDL logical change record (DDL LCR)
DDL logical change record (DDL LCR)
A logical change record (LCR) that describes a data definition language (DDL) change.
declarative rule-based transformation
A rule-based transformation that covers one of a common set of transformation scenarios for row LCRs. Declarative rule-based transformations are run internally without using PL/SQL.
See Also: row logical change record (row LCR) and custom rule-based transformation
A database where messages are consumed. Messages can be consumed when they are dequeued implicitly from a queue by a propagation or apply process, or messages can be consumed when they are dequeued explicitly by an application, a messaging client, or a user.
See Also: consumption
The queue that receives the messages propagated by a propagation from a source queue.
An apply process applies an LCR without running a user procedure.
See Also: logical change record (LCR)
A network in which propagated messages pass through one or more intermediate databases before arriving at a destination database.
A capture process that runs on a database other than its source database.
The database on which a downstream capture process runs.
An apply handler that uses a PL/SQL procedure to try to resolve apply errors. An error handler is invoked only when a row logical change record (row LCR) raises an apply process error. Such an error might result from a conflict if no conflict handler is specified or if the update conflict handler cannot resolve the conflict.
A database object that defines external data that can be referenced in rule conditions. The external data can exist as variables, table data, or both.
Messages are transferred to an exception queue if they cannot be retrieved and processed for some reason.
The messages in a queue are dequeued either by a messaging client when it is invoked by a user or application or by an application or user directly.
In the context of a file group, a reference to a file stored on hard disk. A file is composed of a file name, a directory object, and a file type. The directory object references the directory in which the file is stored on hard disk.
A collection of versions.
A collection of all of the file groups in a database.
The lowest system change number (SCN) in the redo log from which a capture process can capture changes.
The system change number (SCN) beyond which no messages have been applied by an apply process.
See Also: low-watermark
The system change number (SCN) specified for a table below which changes cannot be applied by an apply process.
The messages are captured automatically by a capture process or by synchronous capture and enqueued into a queue.
The messages in a queue are dequeued automatically by an apply process.
The process of preparing database objects for instantiation at a source database, optionally copying the database objects from a source database to a destination database, and setting the instantiation SCN for each instantiated database object.
The system change number (SCN) for a table which specifies that only changes that were committed after the SCN at the source database are applied by an apply process.
An option for DML handlers and error handlers that assembles multiple row LCRs resulting from a change to a single row with LOB columns into a single row LCR. LOB assembly simplifies processing of row LCRs with LOB columns in DML handlers and error handlers.
A capture process that runs on its source database.
A message with a specific format that describes a database change.
See Also: row logical change record (row LCR) and DDL logical change record (DDL LCR)
A separate data dictionary used by a capture process to determine the details of a change that it is capturing. The LogMiner data dictionary is necessary because the primary data dictionary of the source database might not be synchronized with the redo data being scanned by a capture process.
The system change number (SCN) up to which all messages have been applied by an apply process.
See Also: high-watermark
The system change number (SCN) that corresponds to the last checkpoint interval recorded by a capture process.
An apply handler that uses a PL/SQL procedure to process persistent user messages.
See Also: logical change record (LCR)
A rule that is relevant only for a user message of a specific message type.
An optional Oracle Streams client that dequeues persistent LCRs or persistent user messages when it is invoked by an application or a user.
A rule set for an Oracle Streams client that results in the Oracle Streams client discarding a message when a rule in the rule set evaluates to TRUE for the message. The negative rule set for an Oracle Streams client always is evaluated before the positive rule set.
Nonpersistent queues store messages in memory. They are generally used to provide an asynchronous mechanism to send notifications to all users that are currently connected. Nonpersistent queues were deprecated in Oracle Database 10g Release 2. Oracle recommends that you use buffered messaging instead.
A queue in which each message is its own transaction.
See Also: transactional queue
A virtual dependency definition that defines a parent-child relationship between two objects at a destination database.
For a running apply process, the earliest system change number (SCN) of the transactions currently being dequeued and applied. For a stopped apply process, the oldest SCN is the earliest SCN of the transactions that were being applied when the apply process was stopped.
A mechanism that performs work in an Oracle Streams environment and is a client of the rules engine (when the mechanism is associated with one or more rule sets). The following are Oracle Streams clients: capture process, propagation, apply process, and messaging client.
Oracle Streams data dictionary
A separate data dictionary used by propagations and apply processes to keep track of the database objects from a particular source database.
A portion of memory in the System Global Area (SGA) that is used by Oracle Streams. The Oracle Streams pool stores buffered queue messages in memory, and it provides memory for capture processes and apply processes.
A representation of the databases in an Oracle Streams environment, the Oracle Streams components configured in these databases, and the flow of messages between these components.
A logical change record (LCR) that is enqueued into the persistent queue portion of an ANYDATA queue. A persistent LCR can be enqueued in one of the following ways:
Captured implicitly by a synchronous capture and enqueued
Constructed explicitly by an application and enqueued
Dequeued by an apply process and enqueued by the same apply process using the SET_ENQUEUE_DESTINATION procedure in the DBMS_APPLY_ADM package
The portion of a queue that only stores messages on hard disk in a queue table, not in memory.
A non-LCR message of a user-defined type that is enqueued into a persistent queue. A persistent user message can be enqueued in one of the following ways:
Created explicitly by an application and enqueued
Dequeued by an apply process and enqueued by the same apply process using the SET_ENQUEUE_DESTINATION procedure in the DBMS_APPLY_ADM package
A persistent user message can be enqueued into the persistent queue portion of an ANYDATA queue or a typed queue.
A rule set for an Oracle Streams client that results in the Oracle Streams client performing its task for a message when a rule in the rule set evaluates to TRUE for the message. The negative rule set for an Oracle Streams client always is evaluated before the positive rule set.
An apply handler that can receive the commit information for a transaction and use a PL/SQL procedure to process the commit information in any customized way.
A table that has been prepared for instantiation.
A component of a capture process that scans a region defined by the reader server and performs prefiltering of changes found in the redo log. A reader server is a process, and multiple reader servers can run in parallel. Prefiltering entails sending partial information about changes, such as schema and object name for a change, to the rules engine for evaluation, and receiving the results of the evaluation.
An apply handler that uses a PL/SQL procedure to process row LCRs.
See Also: row logical change record (row LCR)
An optional Oracle Streams client that uses an Oracle Scheduler job to send messages from a source queue to a destination queue.
An Oracle Scheduler job used by a propagation to propagate messages.
A schedule that specifies how often a propagation job propagates messages.
A directed network in which the messages being forwarded at an intermediate database are the messages received by the intermediate database, so that the source database for a message is the database where the message originated.
See Also: apply forwarding
A database table where queues are stored. Each queue table contains a default exception queue.
A component of a capture process that is a process that reads the redo log and divides the redo log into regions.
A component of an apply process that dequeues messages. The reader server is a process that computes dependencies between LCRs and assembles messages into transactions. The reader server then returns the assembled transactions to the coordinator process, which assigns them to idle apply servers.
See Also: logical change record (LCR)
real-time downstream capture process
A downstream capture process that can capture changes made at the source database before the changes are archived in an archived redo log file.
The system change number (SCN) that corresponds to the lowest checkpoint interval for which a capture process requires redo data.
The column used to identify a prebuilt update conflict handler.
See Also: conflict resolution
row logical change record (row LCR)
A logical change record (LCR) that describes a change to the data in a single row or a change to a single LONG, LONG RAW, or LOB column in a row that results from a data manipulation language (DML) statement or a piecewise operation. One DML statement can result in multiple row LCRs.
An automatic conversion performed by an internal rule-based transformation when a subset rule evaluates to TRUE in which an UPDATE operation might be converted into an INSERT or DELETE operation.
A database object that enables a client to perform an action when an event occurs and a condition is satisfied.
Any modification to a message when a rule in a positive rule set evaluates to TRUE.
A component of a rule which combines one or more expressions and conditions and returns a Boolean value, which is a value of TRUE, FALSE, or NULL (unknown).
A group of rules.
A built-in part of Oracle that evaluates rule sets.
A rule that is relevant only to a particular schema.
A queue for which Oracle Streams Advanced Queuing (AQ) agents must be associated explicitly with one or more database users who can perform queue operations, such as enqueue and dequeue.
The database where changes captured by a capture process are generated in a redo log, or the database where a synchronous capture that generated LCRs is configured.
The queue from which a propagation propagates messages to a destination queue.
The system change number (SCN) from which a capture process begins to capture changes.
An apply handler that uses one or more SQL statements to process row LCRs.
See Also: row logical change record (row LCR)
A rule that is relevant only to a subset of the rows in a particular table.
A group of columns in a table that is supplementally logged.
See Also: supplemental logging
Additional column data placed in a redo log whenever an operation is performed. A capture process captures this additional information and places it in LCRs, and the additional information might be needed for an apply process to apply LCRs properly at a destination database.
See Also: logical change record (LCR)
An optional Oracle Streams client that uses an internal mechanism to capture DML changes made to tables immediately after the changes are made.
A rule with a system-generated name that was created using the DBMS_STREAMS_ADM package.
A rule that is relevant only to a particular table.
The type of supplemental logging that applies to columns in a particular table.
A collection of the tablespace sets in a file group.
Data of RAW data type that appears in each redo entry and LCR. You can use tags to modify the behavior of Oracle Streams clients and to track LCRs. Tags can also be used to prevent change cycling.
See Also: logical change record (LCR)
A special type of row LCR captured by a capture process or synchronous capture that contains transaction control statements, such as COMMIT and ROLLBACK.
See Also: row logical change record (row LCR)
A queue in which messages can be grouped into a set that are applied as one transaction.
See Also: nontransactional queue
A supplemental log group that logs the before images of specified columns when the table is changed, regardless of whether the change affected any of the specified columns.
See Also: conditional log group
A non-LCR message of a user-defined type. A user message can be a buffered user message or a persistent user message.
See Also: logical change record (LCR)
A virtual dependency definition that defines a table constraint, such as a unique key, or a relationship between the columns of two or more tables.
A collection of related files.
A description of a dependency that is used by an apply process to detect dependencies between transactions being applied at a destination database.
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