摘要:
Described herein are various approaches that allow rules to be used to specify actions, that alleviate the complexity and burden of developing and maintaining rules in a rules-based messaging system, and that provide more efficient ways of evaluating rules. The approaches allow rules to specify user-defined transformation functions for transforming messages, to specify when and how to perform row migration, and to specify other types of actions. Rules are grouped into rule sets. Several types of rule sets, referred to as positive and negative rule sets, allow users to use rules that are less complex to develop and maintain. Rule sets are evaluated more efficiently by attempting to evaluate the rule set with less information than is needed to evaluate all the rules in the rule set. Also, the results of rules evaluations that are based on a set of values are cached for later retrieval.
摘要:
Techniques for replicating data in database systems are described. In an example embodiment, a set of changes is received at a destination database, where the set of changes has been applied at a source database and is being replicated from the source database to the destination database. The set of changes is analyzed and it is determined that the set of changes includes two or more of: a subset of row-level changes, a subset of statement-level changes, and a subset of procedure-level changes. A set of dependencies is determined at least between the changes that are included in the subsets of changes. The changes, in the subsets of changes, are assigned to two or more processing elements. The set of changes is applied to the destination database by executing the two or more processing elements in parallel to each other and based on the set of dependencies.
摘要:
An approach is provided to automatically resolve conflict between instantiation and ongoing data replication operations. In an embodiment, incremental change records that describe one or more database operations are received at a sink entity. Here, all of the one or more database operations have occurred in a second database after a particular time. A first database operation in the one or more database operations to a particular row in the first database is applied. When a conflict with a second database operation that operates on the particular row is detected, one or more compensating actions, which may, but are not limited to, be a different database operation and/or an operation that creates a conflict log entry, may be performed. Here, the second database operation has occurred in the second database prior to the particular time. When the second database operation is to be performed, an appropriate operation may be performed.
摘要:
Described herein are various approaches that allow rules to be used to specify actions, that alleviate the complexity and burden of developing and maintaining rules in a rules-based messaging system, and that provide more efficient ways of evaluating rules. The approaches allow rules to specify user-defined transformation functions for transforming messages, to specify when and how to perform row migration, and to specify other types of actions. Rules are grouped into rule sets. Several types of rule sets, referred to as positive and negative rule sets, allow users to use rules that are less complex to develop and maintain. Rule sets are evaluated more efficiently by attempting to evaluate the rule set with less information than is needed to evaluate all the rules in the rule set. Also, the results of rules evaluations that are based on a set of values are cached for later retrieval.
摘要:
In some messaging system architectures, messages can cycle back to the originator of a message, who may then propagate the message, causing the cycle to be repeated. Described herein are techniques that use rules and fields in a redo log, to manage message flows such that undesired cycles are prevented. The techniques may be used in messaging systems that have various topologies.
摘要:
Techniques for replicating data in database systems are described. In an example embodiment, a set of changes is received at a destination database, where the set of changes has been applied at a source database and is being replicated from the source database to the destination database. The set of changes is analyzed and it is determined that the set of changes includes two or more of: a subset of row-level changes, a subset of statement-level changes, and a subset of procedure-level changes. A set of dependencies is determined at least between the changes that are included in the subsets of changes. The changes, in the subsets of changes, are assigned to two or more processing elements. The set of changes is applied to the destination database by executing the two or more processing elements in parallel to each other and based on the set of dependencies.
摘要:
An approach is provided to automatically resolve conflict between instantiation and ongoing data replication operations. In an embodiment, incremental change records that describe one or more database operations are received at a sink entity. Here, all of the one or more database operations have occurred in a second database after a particular time. A first database operation in the one or more database operations to a particular row in the first database is applied. When a conflict with a second database operation that operates on the particular row is detected, one or more compensating actions, which may, but are not limited to, be a different database operation and/or an operation that creates a conflict log entry, may be performed. Here, the second database operation has occurred in the second database prior to the particular time. When the second database operation is to be performed, an appropriate operation may be performed.
摘要:
A source database system sends information to a destination database system, and each database system generates a separate set of sequence information. A mapping is maintained between the two sets of sequence information. Using the mapping, the destination database system may be used to restore changes lost at the source database system without reinstating the source database. Additionally, queries associated with a particular point in a sequence associated with the sequence information of the source database may be redirected to the destination database, and the destination database system may serve as a logical standby for the source database system. A variety of methods of maintaining and/or extracting the mapping information are disclosed.
摘要:
An approach efficiently and dynamically allocates and de-allocates database instances and nodes between databases. The approach performs this function in a way that accounts for the users of and services hosted by multiple databases.
摘要:
Approaches described herein may be used for provisioning of databases that requires a bulk transfer of data within a distributed computing environment, such as a grid. The approaches do not require the manual intervention of a DBA to, for example, transfer a tablespace between the file systems of operating systems. Instead, the tablespaces may be provisioned automatically and dynamically by a grid computing system whenever it determines the need to dynamically provision a database. In addition, as copies of tablespaces are provisioned, synchronization mechanisms can also be automatically provisioned to keep the tablespaces and their copies in sync.