Oracle International Corporation

Kiran Badrinarain Goyal

Juan R Loaiza

Tirthankar Lahiri

Kothanda Umamageswaran

Selcuk Aya

Boris Erlikhman

Bharat C V Baddepudi

Wei-Ming Hu

Alexander Tsukerman

Vipin Gokhale

Neil J S MacNaughton

Adam Y Lee

Eugene Reddy Ho

Poojan Kumar

Jia Shi

J William Lee

Neil MacNaughton

Bharat Chandra Baddepudi

Roger J Hansen

Nilesh Choudhury

Umesh Panchaksharaiah

Adrian Ng

Sue-Kyoung Lee

Susy Fan

Timothy L Shetler

Brian Hirano

Benoit Dageville

Daniel ManHung Wong

Yunrui Li

Kumar Rajamani

Niloy Mukherjee

Michael Zoll

Dheeraj Pandey

Richard L Frank

Vinay H Srihari

Mark Dilman

Alex Tsukerman

Jaebock Lee

Arvind Nithrakashyap

Kant C Patel

Paul Youn

Hochak Hung

Varun Malhotra

Balasubramanian Narasimhan

Siddhartha Roychowdhury

Aya Selcuk

Bharat CV Baddepudi

Roger Hansen

A storage device uses non-volatile memory devices for caching. The storage device operates in a mode referred to herein as write-back mode. In write-back mode, a storage device responds to a request to write data by persistently writing the data to a cache in a non-volatile memory device and acknowledges to the requestor that the data is written persistently in the storage device. The acknowledgement is sent without necessarily having written the data that was requested to be written to primary storage. Instead, the data is written to primary storage later.

Write-back storage cache based on fast persistent memory

Techniques are provided for using an intermediate cache to provide some of the items involved in a scan operation, while other items involved in the scan operation are provided from primary storage. Techniques are also provided for determining whether to service an I/O request for an item with a copy of the item that resides in the intermediate cache based on factors such as a) an identity of the user for whom the I/O request was submitted, b) an identity of a service that submitted the I/O request, c) an indication of a consumer group to which the I/O request maps, d) whether the I/O request is associated with an offloaded filter provided by the database server to the storage system, or e) whether the intermediate cache is overloaded. Techniques are also provided for determining whether to store items in an intermediate cache in response to the items being retrieved, based on logical characteristics associated with the requests that retrieve the items.

Selectively reading data from cache and primary storage based on whether cache is overloaded

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 to provide some of the items involved in a scan operation, while other items involved in the scan operation are provided from primary storage. Techniques are also provided for determining whether to service an I/O request for an item with a copy of the item that resides in the intermediate cache based on factors such as a) an identity of the user for whom the I/O request was submitted, b) an identity of a service that submitted the I/O request, c) an indication of a consumer group to which the I/O request maps, or d) whether the intermediate cache is overloaded. Techniques are also provided for determining whether to store items in an intermediate cache in response to the items being retrieved, based on logical characteristics associated with the requests that retrieve the items.

Selectively reading data from cache and primary storage

One embodiment of the present invention provides a system for performing selective encryption/decryption in a data storage system. During operation, the system receives a data block from a storage medium at an input/output layer, wherein the input/output layer serves as an interface between the storage medium and a buffer cache. Next, the system determines whether the data block is an encrypted data block. If not, the system stores the data block in the buffer cache. Otherwise, if the data block is an encrypted data block, the system retrieves a storage-key, wherein the storage-key is associated with a subset of storage, which is associated with the encrypted data block. Using the storage-key, the system then decrypts the encrypted data block to produce a decrypted data block. Finally, the system stores the decrypted data block in the buffer cache, wherein the data block remains encrypted in the storage medium.

Method and apparatus for performing selective encryption/decryption in a data 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 partial reverse key index is described, which allows distributed contention as resources vie to insert data into an index as well as allows range scans to be performed on the index. To do so, before an index entry for a key value is inserted into an index, the key value is transformed using a transformation operation that affects a subset of the order of the key value. The index entry is then inserted based on the transformed key value. Because the transformation operation affects the order of the key value, the transformed values associated with two consecutive key values will not necessarily be consecutive. Therefore, the index entries associated with the consecutive key values may be inserted into unrelated portions of the index.

Partial key indexes

A method and apparatus for auto-tuning memory is provided. Memory on a computer system comprises at least one shared memory area and at least one private memory area. Addresses in the shared memory area are accessible to multiple processes. Addresses in the private memory area are dedicated to individual processes. Initially, a division in the amount of memory is established between the shared and private memory areas. Subsequently, a new division is determined. Consequently, memory from one memory area is 'given' to the other memory area. In one approach, such sharing is achieved by causing the shared and private memory areas to be physically separate from each other both before and after a change in the division. The division of the amount of memory may be changed to a new division by deallocating memory from one of the memory areas and allocating that memory to the other of the memory areas.

Managing memory in a system that includes a shared memory area and a private memory area

Allocation of memory is optimized across multiple pools of memory, based on minimizing the time it takes to successfully retrieve a given data item from each of the multiple pools. First data is generated that indicates a hit rate per pool size for each of multiple memory pools. In an embodiment, the generating step includes continuously monitoring attempts to access, or retrieve a data item from, each of the memory pools. The first data is converted to second data that accounts for a cost of a miss with respect to each of the memory pools. In an embodiment, the second data accounts for the cost of a miss in terms of time. How much of the memory to allocate to each of the memory pools is determined, based on the second data. In an embodiment, the steps of converting and determining are automatically performed, on a periodic basis.

Techniques for automated allocation of memory among a plurality of pools

A standby database system or another replica data system replicates changes, made to data blocks at a source database system or another primary data copy, to replicas of the data blocks at the standby database system or other replica. While replicating the changes to the data blocks thereof, the standby database system (or other replica) receives queries (or reads) issued thereto and computes the queries based on data read from the data blocks thereof.

Readable physical storage replica and standby database system

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

An electronic and computerized system that coalesces write operations using a buffer cache which stores data waiting to be written back to a disk of the electronic and computerized system is described. Dirty data blocks with consecutive data block addresses in the buffer cache are coalesced and written to the disk together. The disk head movements for performing the disk IOs are significantly reduced, thereby allowing the electronic and computerized system to maintain a high IO throughput and high peak performance with fewer disks.

Reducing disk IO by full-cache write-merging

Growing community of inventors

Foster City, CA, United States of America

Kiran Badrinarain Goyal