Efficient determination of committed changes

    公开(公告)号:US10303788B2

    公开(公告)日:2019-05-28

    申请号:US15253630

    申请日:2016-08-31

    Abstract: A minimum value (MV) is computed for start timestamps that each correspond to an uncommitted transaction. In an embodiment, the MV is computed for a pluggable database that is open on at least first and second instances of a database. The MV is computed for the first instance as of a first current timestamp (CT). The MV and the first CT are communicated to a second instance that has a second CT. If the first and second CTs are equal, the second instance store the MV. If the first CT is bigger, the second CT also becomes equal to the first CT. If the first CT is smaller, the MV is discarded, and the first CT becomes equal to the second CT. In an embodiment, if the MV remains unchanged for a predetermined time period, a start timestamp corresponding to the MV is advanced to a current or future timestamp.

    Intelligent network resource manager

    公开(公告)号:US10250510B2

    公开(公告)日:2019-04-02

    申请号:US14488161

    申请日:2014-09-16

    Abstract: A method and apparatus for intelligent network resource manager for distributed computing systems is provided. A first priority is assigned to a first virtual channel set that includes at least two virtual channels of a plurality of virtual channels associated with a physical communication channel. A second priority is assigned to a second virtual channel set that includes at least one virtual channel of the plurality of virtual channels. The first virtual channel set has more virtual channels than the second virtual channel set. Outbound messages of the first priority are directed to virtual channels of the first virtual channel set. Outbound messages of the second priority are directed to virtual channels of the second virtual channel set. The virtual channels are processed in a round-robin order, where processing includes sending the outbound messages over the physical communication channel.

    Automatic caching of scan and random access data in computing systems

    公开(公告)号:US10229161B2

    公开(公告)日:2019-03-12

    申请号:US14489221

    申请日:2014-09-17

    Abstract: Approaches, techniques, and mechanisms are disclosed for improved caching in database systems that deal with multiple data access patterns, such as in database systems that interface with both OLTP and Data Warehouse clients. A cache is deployed between a database server and a storage system that stores data units. Some of the data units accessed by the database server are buffered within the cache. The data units may be associated with data access patterns, such as a random data access pattern or a scan data access pattern, in accordance with which the database server is or appears to be accessing the data units. A processor selects when to cache data units accessed by the database server, based at least on the associated data access patterns. Recent access counts may also be stored for the data units, and may further be utilized to select when to cache data units.

    Reducing data I/O using in-memory data structures

    公开(公告)号:US10198363B2

    公开(公告)日:2019-02-05

    申请号:US15268524

    申请日:2016-09-16

    Abstract: Techniques are described herein for generating and using in-memory data structures to represent columns in data block sets. In an embodiment, a database management system (DBMS) receives a query for a target data set managed by the DBMS. The query may specify a predicate for a column of the target data set. The predicate may include a filtering value to be compared with row values of the column of the target data set. Prior to accessing data block sets storing the target data set from persistent storage, the DBMS identifies an in-memory summary that corresponds to a data block set, in an embodiment. The in-memory summary may include in-memory data structures, each representing a column stored in the data block set. The DBMS determines that a particular in-memory data structure exists in the in-memory summary that represents a portion of values of the column indicated in the predicate of the query. Based on the particular in-memory data structure, the DBMS determines whether or not the data block set can possibly contain the filtering value in the column of the target data set. Based on this determination, the DBMS skips or retrieves the data block set from the persistent storage as part of the query evaluation.

    Selectively reading data from cache and primary storage
    16.
    发明授权
    Selectively reading data from cache and primary storage 有权
    从缓存和主存储中选择性地读取数据

    公开(公告)号:US09361232B2

    公开(公告)日:2016-06-07

    申请号:US13839251

    申请日:2013-03-15

    Abstract: 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.

    Abstract translation: 提供了使用中间缓存来提供扫描操作中涉及的一些项目的技术,而从主存储器提供涉及扫描操作的其他项目。 还提供了用于基于以下因素来确定是否对具有驻留在中间高速缓存中的项目的副本的项目的I / O请求进行服务的技术,例如:a)向其提交I / O请求的用户的身份 ,b)提交I / O请求的服务的身份,c)I / O请求所映射的消费者组的指示,或d)中间缓存是否过载。 还提供了基于与检索项目的请求相关联的逻辑特征来确定是否将项目存储在中间高速缓存中以响应于正被检索的项目的技术。

    Rapid Recovery From Downtime Of Mirrored Storage Device
    18.
    发明申请
    Rapid Recovery From Downtime Of Mirrored Storage Device 审中-公开
    镜像存储设备停机时间快速恢复

    公开(公告)号:US20140281272A1

    公开(公告)日:2014-09-18

    申请号:US13801319

    申请日:2013-03-13

    Abstract: No-loss rapid recovery performs resynchronization efficiently while concurrently allowing availability to mirrored data on the storage device. No-loss rapid recovery has two stages and involves storage devices that have both a non-volatile cache and primary storage and that operate as mirror buddies. The first stage is referred to herein as the buddy-retention stage. During the buddy-retention stage, writes to mirrored data are not performed on the offline mirror buddy but are performed on the online mirror buddy. The mirrored data changed in the online mirrored buddy is retained in the non-volatile cache of the retention buddy. The next stage is referred to herein as the rapid resynchronization stage. In this stage, the changed mirrored data retained by the retention buddy for no-loss rapid recovery is used to resynchronize the offline buddy. The storage device is resynchronized using the changed mirrored data retained in the cache of the mirror buddy.

    Abstract translation: 无损失快速恢复有效地执行重新同步,同时允许可用性在存储设备上镜像数据。 无损快速恢复有两个阶段,涉及具有非易失性缓存和主存储并且作为镜像伙伴操作的存储设备。 第一阶段在本文中称为保留阶段。 在好友保留期间,对镜像数据的写入不会在离线镜像伙伴上执行,而是在在线镜像伙伴上执行。 在线镜像伙伴中更改的镜像数据保留在保留伙伴的非易失性缓存中。 下一阶段在本文中被称为快速再同步化阶段。 在这个阶段,由保留伙伴保留的无损失快速恢复所更改的镜像数据用于重新同步脱机伙伴。 使用保留在镜像伙伴缓存中的已更改的镜像数据重新同步存储设备。

    PMEM CACHE RDMA SECURITY
    20.
    发明申请

    公开(公告)号:US20210303154A1

    公开(公告)日:2021-09-30

    申请号:US16831337

    申请日:2020-03-26

    Abstract: Techniques are described for providing one or more clients with direct access to cached data blocks within a persistent memory cache on a storage server. In an embodiment, a storage server maintains a persistent memory cache comprising a plurality of cache lines, each of which represent an allocation unit of block-based storage. The storage server maintains an RDMA table that include a plurality of table entries, each of which maps a respective client to one or more cache lines and a remote access key. An RDMA access request to access a particular cache line is received from a storage server client. The storage server identifies access credentials for the client and determines whether the client has permission to perform the RDMA access on the particular cache line. Upon determining that the client has permissions, the cache line is accessed from the persistent memory cache and sent to the storage server client.

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