Oracle International Corporation

Tong Zhou

Douglas N Surber

Jean De Lavarene

Carol L Colrain

Kevin S Neel

Stephen Felts

Nancy Reiko Ikeda

Ashok Shivarudraiah

Stefan Heinrich Roesch

Vidya Hegde

Naresh Revanuru

Alexander J Somogyi

Mark Dilman

Wei Ming Hu

Leonid Novak

Ilya Taranov

Ravi Shankar Thammaiah

David Scott Merrill

Jonathan Giloni

Pankaj Chand

Arturo Ismael Quinto

Paul Parkinson

Rajkumar Arockia Irudayaraj

Nicolas Michael

Rohan Ankalikar

Edward Shirk

Paul Lo

Manoj Dhanapal

Frances Zhao-Perez

Alex Somogyi

Wei Hu

Rajkumar Irudayaraj

Francis Zhao-Perez

Nancy R Ikeda

Techniques are disclosed herein for identifying, recording and restoring the state of a database session and various aspects thereof. A session template data structure is generated that includes session attribute values describing various aspects of the session that is established between a client system and a database management system (DBMS and enables the client system to issue to the DBMS commands for execution. Based on the session attribute values, DBMS may generate a template identifier corresponding to the session template data structure. The template identifier may be stored in an association with the session state that it partially (or in whole) represents. In an embodiment, when another state of a session is captured, if the template identifier for the state is the same, then rather than storing the attribute-value pairs for the other state, the template identifier is further associated with the other state. In an embodiment, a request boundary is detected where the session is known to be at a recoverable point. If recovery of the session is needed, the session state is restored, and replay of commands start from this point. Each command replayed is verified to produce the same session state as it produced by the original execution. If the session is determined to be a safe point, then all the commands recorded for replay prior to the safe point may be deleted. In an embodiment, the template is used to set the initial state when borrowing from a session pool. The state tracking is also used to identify that the session can be failed over safely during planned operation as the session is unlikely to drain by itself even when not used.

Session state tracking

In accordance with an embodiment, described herein are systems and methods for providing direct access to a sharded database. A shard director provides access by software client applications to database shards. A connection pool (e.g., a Universal Connection Pool, UCP) and database driver (e.g., a Java Database Connectivity, JDBC, component) can be configured to allow a client application to provide a shard key, either during connection checkout or at a later time; recognize shard keys specified by the client application; and enable connection by the client application to a particular shard or chunk. The approach enables efficient re-use of connection resources, and faster access to appropriate shards.

System and method for providing direct access to a sharded database

Techniques are disclosed herein for identifying, recording and restoring the state of a database session and various aspects thereof. A session template data structure is generated that includes session attribute values describing various aspects of the session that is established between a client system and a database management system (DBMS and enables the client system to issue to the DBMS commands for execution. Based on the session attribute values, DBMS may generate a template identifier corresponding to the session template data structure. The template identifier may be stored in an association with the session state that it partially (or in whole) represents. In an embodiment, when another state of a session is captured, if the template identifier for the state is the same, then rather than storing the attribute-value pairs for the other state, the template identifier is further associated with the other state. In an embodiment, a request boundary is detected where the session is known to be at a recoverable point. If recovery of the session is needed, the session state is restored, and replay of commands start from this point. Each command replayed is verified to produce the same session state as it produced at original execution. If the session is determined to be a safe point, then all the commands recorded for replay prior to the safe point may be deleted. In an embodiment, the template is used to set the initial state when borrowing from a session pool The state tracking is also used to know that the session can be failed over safely during planned operation as the session is unlikely to drain by itself even when not used.

Session templates

In accordance with an embodiment, the system enables access to a sharded database using a cache and a shard topology. A shard-aware client application connecting to a sharded database can use a connection pool (e.g., a Universal Connection Pool, UCP), to store or access connections to different shards or chunks of the sharded database within a shared pool. As new connections are created, a shard topology layer can be built at the database driver layer, which learns and caches shard key ranges to locations of shards. The shard topology layer enables subsequent connection requests from a client application to use a fast key path access to the appropriate shard or chunk.

System and method for providing access to a sharded database using a cache and a shard technology

Techniques are described for closing one or more connections with a database management system (DBMS) as part of a planned operation such as maintenance and load balancing. In an embodiment, a request is received for a planned operation of a database server of a DBMS that requires releasing and migrating database sessions. Over a database connection with the database server, the DBMS or a Client-Driver on the client system that interfaces with the DBMS, may receive request(s) from the client system. Based on the request(s), a safe point, for the database connection with the database server, at which the database connection of the client system with the database server can be closed without affecting the success of execution of next one or more command that the client system intended to request the DBMS to execute on the database server, is determined. In an embodiment, in response to the request(s), the DBMS and/or Client-Driver, while the connection is valid, provide to the client system an invalid status for a connection test request. Such a response may cause the client system to use a different database connection to connect with the DBMS. After returning the response to the client system, the DBMS and/or Client-Driver causes the database session with the DBMS to close. In an embodiment, for database sessions to be released, the DBMS identifies a safe point in a database session by a detected request boundary or where the session states are determined to be recoverable or the failover is determined to be expected to succeed. At such a safe point, all database session states are known, and failing the session over to another database instance offering the requested service can be performed safely and transparent to applications.

Safe release of database sessions for planned maintenance operations

A system and method for transparent multi key-value weighted attributed connection using uni-tag connection pools. In accordance with an embodiment, a connection pool enables labeling of connections that software applications can use to access a database. A connection pool associated with a database enables tagging of connection pools at the database and allows applications to selectively obtain connections based on tags. A request is received from an application to query data from the database using a labeled connection or low-cost alternative. If a low-cost connection is found, but requires configuration, the system returns unmatched labels for use by the application in configuring its environment to use the connection. The system can also generate a tag for the connection. Upon subsequent release of the database session, the tag can be made available for subsequent use of the tag, or a tagged connection, by the same or by other applications.

System and method for transparent multi key-value weighted attributed connection using uni-tag connection pools

A process, apparatus, and computer-readable medium are provided for rebuilding a database session when a previous database session becomes unavailable and the commands previously sent for execution on the previous database session satisfy certain criteria. The process includes determining whether or not a set of commands sent by a client for execution on the previous database session is acceptable to replay based at least in part on whether or not the set of commands satisfies one or more criteria. The process further includes determining that the previous database session is unavailable due to a planned or unplanned recoverable error. In response to determining that the previous database session is unavailable, if the set of commands is acceptable for replay, the set of commands is sent for execution on a new database session to rebuild the state, which was exposed to the client from the previous database session, on the new database session. The process masks the outage from the application.

Recovering stateful read-only database sessions

Described herein is a system and method for providing a shareable global cache for use with a database environment. In accordance with an embodiment, a shareable global cache is used for caching connections to database instances. When a request is received for a particular service, the system looks for an idle connection to that service, and, if none is available, locates an existing connection to a database instance serving that service and switches a service on the existing connection to that service.

System and method for providing a shareable global cache for use with a database environment

A system and method for a planned migration of service connections from a first database instance to a second database instance in a clustered database. In accordance with an embodiment, a data source and connection pool enable access by a software application to a service on the first database instance. The data source is associated with a parameter specifying a delay-for-planned-draining, and a parameter specifying a planned-draining-period, which are used to rebalance connections when relocating a service. When a service is stopped on the first database instance, the connection pool receives a 'service down' event from a notification service, and maintains the connections up to a time corresponding to the delay-for-planned-draining. When a 'service up' event is received, the connection pool spreads migration of the connections from the first to second database instance over the planned-draining-period.

System and method for planned migration of service connections

Transactional and non-transactional data for maintaining session state is described. In a session, a server instance receives, from a client, a request to execute transactional commands and non-transactional commands. The server instance sends at least one first directive executable at the client to store, in a first set of information, one or more first items representing one or more particular transactional commands that are open but not yet committed. The first set of information is maintained separately from a second set of information including one or more second items representing one or more particular non-transactional commands that have been processed. Based on committing one or more particular transactional commands, the server instance sends at least one second directive executable at the client to purge, from the first set of information, the one or more first items without purging, from the second set of information, the one or more second items.

Transactional and non-transactional data for maintaining session state

Described herein is a system and method for providing a level 2 connection cache for use with a database environment. In accordance with an embodiment, a second level, or level 2 (L2), connection cache is used to cache no-session connections for use with a database. When a connection is requested, a no-session connection (NSC) can be retrieved from the cache and a database session is attached. Later, when the connection is closed, the database session is logged off and the no-session connection returned to the cache for subsequent use.

System and method for providing a second level connection cache for use with a database environment

A system and method for connection labeling for use with connection pools, including support for cloud-based multi-tenant environments using connection labeling. In accordance with an embodiment, the system comprises a connection pool, including a plurality of connection objects which provide connections that software applications can use to make requests to access the database, wherein each of the connections can be labeled according to the configuration of particular applications; and a connection pool logic that identifies connections labeled as high-cost connections, and controls the creation or repurposing of high-cost connections to serve requests from the multiple tenants or tenant applications.

Support for cloud-based multi-tenant environments using connection labeling

A system and method for connection labeling for use with connection pools. In accordance with an embodiment, the system comprises a connection pool, including a plurality of connection objects which provide connections that software applications can use to make requests to access the database, wherein each of the connections can be labeled according to the configuration of particular applications; and a connection pool logic that identifies connections labeled as high-cost connections, and avoids using those high-cost connections to serve requests when the total number of connections is below a particular threshold value.

Growing community of inventors

Merrick, NY, United States of America

Tong Zhou