Oracle International Corporation

Eugene Reddy Ho

Tolga Yurek

Juan R Loaiza

Angelo Pruscino

Wilson Wai Shun Chan

Kiran Badrinarain Goyal

Vipin Gokhale

Kothanda Umamageswaran

Wei-Ming Hu

Michael Zoll

Neil MacNaughton

Alexander Tsukerman

Selcuk Aya

Neil J S MacNaughton

Roger J Hansen

Adam Y Lee

Boris Erlikhman

Bharat C V Baddepudi

Adrian Ng

Tirthankar Lahiri

Tak Fung Wang

Wilson Wai Chan

Stefan Heinrich Roesch

John C Hsu

Deepti Srivastava

Chen Yang

Beverly Zane

Kotaro Ono

Herbert Van Den Bergh

Aya Selcuk

Bharat CV Baddepudi

Roger Hansen

According to embodiments, reconfiguration of lock masters for a cluster of nodes is optimized using coordinated hash indexes to index into the master hash table and into local hash tables stored on the nodes of the cluster. A DBMS uses a hybrid hash index, a portion of which represents a corresponding master hash index, to index into both the master hash table and into a local hash table for a given lock. The hash index used to store lock metadata in a particular local hash table bucket, on a particular node, encodes the lock master index, for a master hash table, to which the locks in the local hash table bucket correspond. Only the portions of the local hash table on the lock master that correspond to the index of the master hash table bucket need to be scanned in order to perform needed tasks for lock master reconfiguration.

Coordinated hash table indexes to facilitate reducing database reconfiguration time

Techniques for adaptive trace logging include, in one embodiment, obtaining input data on trace logging behavior and computing resources used by trace logging. Based on the obtained input data, an adaptive trace logging module automatically takes action at runtime to reduce the amount of computing resources consumed by tracing logging. For example, the action taken may include decreasing a trace logging level of an executing software program to reduce the number of trace logging messages added to a trace log. In another embodiment, the techniques include detecting a condition of an executing software program that warrants a change to a trace logging level of the executing program. The adaptive trace logging module automatically changes the trace logging level of the executing program as-needed for the detected condition. For example, the adaptive trace logging module may increase the trace logging level of an executing program upon detecting a deadlock or other abnormal condition of the executing program. By automatically increasing the trace logging level upon detecting an abnormal condition, additional trace logging messages may be written to a trace log aiding diagnosis and troubleshooting of the condition.

Techniques for adaptive trace logging

Techniques are provided for using an intermediate cache between the shared cache of an application and the non-volatile storage of a storage system. The application may be any type of application that uses a storage system to persistently store data. The intermediate cache may be local to the machine upon which the application is executing, or may be implemented within the storage system. In one embodiment where the application is a database server, the database system includes both a DB server-side intermediate cache, and a storage-side intermediate cache. The caching policies used to populate the intermediate cache are intelligent, taking into account factors that may include which object an item belongs to, the item type of the item, a characteristic of the item, or the type of operation in which the item is involved.

Caching data between a database server and a storage system

Techniques are provided for using an intermediate cache between the shared cache of a database server and the non-volatile storage of a storage system. The intermediate cache may be local to the machine upon which the database server is executing, or may be implemented within the storage system. In one embodiment, the database system includes both a DB server-side intermediate cache, and a storage-side intermediate cache. The caching policies used to populate the intermediate cache are intelligent, taking into account factors that may include which database object an item belongs to, the item type of the item, a characteristic of the item; or the database operation in which the item is involved.

A method and apparatus for managing locks in a database system is provided. A master node grants a lock on a first resource and a group of resources that includes the first resource to a first requester node. The requester node receives a mapping corresponding to the group of resources that may indicate that a lock already exists for a second resource in the group. If the requester node desires a lock on a resource located in the group, the requester node grants itself the lock without notifying the master node. A second requester node requests a lock for a particular resource in the group of resources. The first requester node grants the lock on the particular resource and updates the mapping to indicate that a different node holds a lock for the particular resource.

Adaptive region locking

Methods and apparatuses for providing access to data in a cluster database are described. Embodiments of the invention include identifying situations in which many nodes require relatively equal access to a data block, and taking appropriate measures to improve the performance of the system in these situations. For example, a node may automatically downgrade its lock from an X lock to an S lock as soon as it has finished a modification of the data. S locks are sent to other nodes in the system as soon as a modification is complete. Modifications to the data are also sent to other nodes in the system as soon as a modification is complete. Depending on the size of the data modification, the entire data block may be sent, or only the modifications to the data may be sent.

Cluster delta push

Techniques are provided for performing changes to a resource governed by a locking mechanism. An entity (such as a server instance in a database system cluster) requests permission to modify the resource. In response to the request, the entity receives a first lock on the resource, which grants permission to perform the change to the resource without making the change permanent. After receiving the first lock, the entity performs the change to a copy of the resource that resides in shared memory without making another copy of the resource. After performing the change and until receiving permission to make the change permanent, the entity prevents the change to the resource from becoming permanent. After performing the change, the entity receives a second lock on the resource, which grants the entity permission to make the change permanent. After receiving the second lock, the entity ceases to prevent the change to the resource from becoming permanent.

Techniques for improved read-write concurrency

Techniques are described herein for handling lock-related inconsistencies. As mentioned above, such inconsistencies occur when two or more sets of lock information, relating to the same resource, convey inconsistent information about locks requested and/or granted on that resource. In general, the techniques involve causing the locally-stored lock information about a resource to be sent to the master node of the resource. The master node of the resource compares the lock information thus received against the lock information maintained by the master node. Based on the comparison, the master node determines how to resolve the lock-related inconsistency, and sends messages to those nodes that need to change their local lock information for the resource. Once all of the lock information has been made consistent, the resource made available for access.

Techniques for handling lock-related inconsistencies

Growing community of inventors

Fremont, CA, United States of America

Eugene Reddy Ho