Oracle International Corporation

Other

Sanjay Kaluskar

Sreenivas Gollapudi

Wei Wang

Namit Jain

James William Stamos

Lakshminarayanan Luxi Chidambaran

Srinath Krishnaswamy

Debashish Chatterjee

Neerja Bhatt

Lik Wong

Hakan Jakobsson

Graham Wood

Mehul Dilip Bastawala

Edwina Lu

Chao Liang

Benoit Dageville

Juan R Loaiza

Tirthankar Lahiri

Jonathan D Klein

Karl Dias

Shailendra Mishra

Sumanta Kumar Chatterjee

Dieter Gawlick

Krishnan Meiyyappan

Kapil Laxmikant Surlaker

Margaret Susairaj

Dmitry Mikhailovich Potapov

Venkateshwaran Venkataramani

Leonidas Galanis

Leng Leng Tan

Ravikanth Kasamsetty

Yujun Wang

Anindo Roy

Eric P Voss

David M Alpern

Archna Kalra Johnson

Richard Sarwal

Varun Malhotra

Christopher P Racicot

James Feenan

Dmitry Frumkin

Ravi Koti

Ronald M Decker

Techniques determine a quantity of rows to fetch based on memory available on a client computer and the fetch state of cursors. The techniques are used to determine a quantity of rows for 'pre-fetching'. Under pre-fetching, rows in addition to those requested by an application are fetched from a database instance and stored in a 'pre-fetch buffer'. The pre-fetch quantities are based on an amount of memory that is deemed available for pre-fetch buffers on a client computer and the number of cursors in the fetch state for a session at a given moment. Pre-fetching is used to hasten session migration. By fetching a quantity of rows that is larger than would be fetched if only the application-specified quantity were fetched, the fetch phase of a cursor is completed sooner. An earlier completion of the fetch phase of a session's cursors allows migration of the session to be completed sooner.

Cursor pre-fetching

A session established for an application is suspended from an instance and later resumed on the server or a different server. When a session is suspended, its state is captured and persistently stored as a session image in a data repository, and the session is terminated. When the session is resumed, a new session is established on an instance, the session image of the session to resume is retrieved from the repository and restored to the newly established session. The suspension and resumption of a session may be initiated by an application, which may request the suspension and resumption of a session.

Suspending and resuming of sessions

A method, system, and computer program product for cost based analysis for data access in a database management system. In one approach, the method, system, and computer program product identifies data to access. A first cost for direct I/O storage access and a second cost for cache access are then determined for accessing the data. A comparison between the first cost and the second cost is then performed. Finally, a first portion of identified data is accessed based at least in part upon the comparison.

Cost based analysis of direct I/O access

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.

Partial evaluation of rule sets

A method and apparatus for capturing database system workload and replaying that workload in a database system is provided. According to one aspect, in order to subject a test database system to the same workload to which the production database system actually would be subjected, a database server in the production system captures and records workload that the database server receives from external entities. This captured workload is processed. Processes external to a database server in the test database system send the processed workload to that database server. As a result, the test database system is subjected to the same workload to which the production database system originally was subjected. The foregoing technique permits a database administrator to determine how the production database system will fare if the difference that is present in the test database system is introduced into the production database system.

Database workload capture and replay architecture

A cache with a database system that contains a subset of the objects stored in another database system. The cache database system responds to a request that contains a reference to an object that is not in the cache by redirecting the request to the other database system when the request is executed in the cache's database system. Redirection is done by rewriting requests that refer to objects that are not in the cache. In one kind of rewriting, a cursor is marked to indicate redirection, and when the cursor is executed in the cache database system, it is redirected to the other database system for execution. In the other kind, calls to stored procedures that are not present in the cache database system are rewritten as remote procedure calls to the stored procedures in the other database system.

Redirection of misses in queryable caches

Techniques allow a client to be migrated from a session that has been established for a client on a server to another session on another server in a way that is a transparent to the application for which the initial session was established. The sessions are migrated under conditions in which a copy of session state of the session to migrate from the source node does not have to be captured and restored to a destination session.

Transparent migration of stateless sessions across servers

A system, method, computer program and system for suspending a result set and continuing from a suspended result set for a scrollable cursor is disclosed. The rows from a row source corresponding to the scrollable cursor result set are suspended into storage so that when a fetch is requested the data can be sent (continued) from the suspended storage and does not depend on the original scrollable cursor row source or session to be available.

Suspending a result set and continuing from a suspended result set for scrollable cursors

A system, method, computer program and system for suspending a result set and continuing from a suspended result set for a cursor is disclosed. The rows from a row source corresponding to the cursor result set are suspended into storage so that when a fetch is requested the data can be sent (continued) from the suspended storage and does not depend on the original cursor row source or session to be available.

Suspending a result set and continuing from a suspended result set

Utilizing rules in a distributed information sharing system

A system, method, computer program and system for suspending a result set and continuing from a suspended result set for transparent session migration is disclosed. The rows from a row source are suspended into storage, so that after session migration, the client fetches can transparently continue from the suspended result set.

Suspending a result set and continuing from a suspended result set for transparent session migration

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.

Preventing change cycling using rules and redo tags in a redo log

Techniques allow a client to be switched from a session on a server to another session on another server in a way that is a transparent to the application for which the initial session was established. Thus, under transparent session migration, a client is switched between sessions without executing application instructions tailored to accomplish the migration. Instead, a client-side interface component, through which the application interacts with the server, handles details of migration, modifying the internal state of the client-side interface component to effect the same. Legacy applications do not have to be modified in order to institute techniques described herein.

Transparent session migration across servers

When a request for a shutdown of a server (e.g. database server) is requested, existing sessions established for the clients are migrated to another server. Some sessions may not be migrated for various reasons; these sessions may be terminated without migrating them.

Database shutdown with session migration

A method and apparatus for migrating the session state of an original session from a first node to a second node, such that a process, executing in the migrated session, may enqueue and dequeue messages from a queue of messages and experience the same behavior from the queue of messages as if the process was enqueuing and dequeuing messages in the original session. Advantageously, all the benefits of migrating a session from one node to another node may be realized, even when the session contains queuing state information that describes the state of a queue of messages. Data that indicates how many messages one or more subscribers have removed from the queue of messages may also be stored to preserve proper behavior of the queue of messages for multiple subscribers when sessions are migrated.

Capturing and re-creating the state of a queue when migrating a session

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Menlo Park, CA, United States of America

Sanjay Kaluskar