A shared-nothing database system is provided in which parallelism and workload balancing are increased by assigning the rows of each table to “slices”, and storing multiple copies (“duplicas”) of each slice across the persistent storage of multiple nodes of the shared-nothing database system. When the data for a table is distributed among the nodes of a shared-nothing system in this manner, requests to read data from a particular row of the table may be handled by any node that stores a duplica of the slice to which the row is assigned. For each slice, a single duplica of the slice is designated as the “primary duplica”. All DML operations (e.g. inserts, deletes, updates, etc.) that target a particular row of the table are performed by the node that has the primary duplica of the slice to which the particular row is assigned. The changes made by the DML operations are then propagated from the primary duplica to the other duplicas (“secondary duplicas”) of the same slice.

Methods and systems relating to a file distribution scheme in a computer network are disclosed that distributes files in an efficient manner that reduces, among other things, network traffic. In an embodiment of the invention, a method for updating a file is disclosed. In such a method, unique chunks in a first version of a digital file are identified. For a second version of the digital file, chunks that are the same as in the first version are identified. Recompilation information is generated and stored for these identified chunks. Also, for the second version of the digital file, chunks in the second version that are different from chunks in the first version are identified. Recompilation information is generated and stored for these identified chunks. With this information, the second version of the digital file is completely defined and can be efficiently stored.

A computer-implemented method, system, and computer program product for managing history metadata of a file. The method may include accessing a first file with delta information. The method may also include determining a portion of the first file to be moved. The method may also include reviewing the delta information of the first file for changes to the portion in the delta information. The method may also include, in response to reviewing the delta information, generating a portion delta history for the portion. The method may also include inserting the portion in a position in a second file, where the portion is inserted with the portion delta history. The method may also include generating new delta information for the second file, where the new delta information includes the portion delta history of the inserted portion.

Examples may include backup objects for fully provisioned volumes with thin lists of chunk signatures. Examples may generate one or more full lists of chunk signatures for the address space of a fully provisioned volume, compare each chunk signature of the full list to an unused region chunk signature representing a chunk of an unused region of the fully provisioned volume, generate metadata to indicate used regions of the fully provisioned volume, based on the comparisons, and generate from the one or more full lists, one or more thin lists omitting all chunk signatures determined to match the unused region chunk signature.

Techniques for managing snapshots of a storage object in a data storage system based on the data churn delta between the latest snapshot and the current data of the storage object. The techniques include, having specified minimum and maximum data loss tolerances for a parent object, creating successive snapshots of the parent object, each snapshot being created at a scheduled time interval or a time when the minimum data loss tolerance has been reached/exceeded. The techniques include obtaining the total data churn between the latest snapshot and the parent data, and determining whether the total data churn has reached or exceeded the maximum data loss tolerance. The techniques include, having determined that the total data churn has reached or exceeded the maximum data loss tolerance, retaining only those snapshots that have not exceeded the maximum data loss tolerance, and discarding all snapshots that have exceeded the maximum data loss tolerance.

Delta compression method, system and computer program product. Portions of source and target data files are hashed using a hashing function. A target data file is compared against the source data file to determine at least one delta difference between the files. A source data file hashing table is generated. The table includes hashed portions of the source and target data files stored in corresponding source file offset locations and corresponding target file offset locations, respectively. Portions of the source and target files are compared using corresponding source and target file offset locations. At least one common sequence of characters in the portions of the source and target files is determined based on the comparison. A patch file is generated based on the determined sequence of characters.

The present disclosure is directed to persisting values in a computing environment, particularly using computer programs that run on a virtual machine. An illustrative method includes first launching a computer program, preferably within the environment of a virtual machine. The method further includes loading a plurality of classes associated with the computer program into memory by way of a special class loader. This class loader scans at least one class of classes loaded into memory for at least one persistence-annotated field within that class. The special class loader further writes byte code into a class that contains the at least one persistence-annotated field. The byte code that is added to the class causes a first object that is later instantiated from the at least one class to have the persistence-annotated field.

A delta set information management device (delta device) stores full versions of files and updates such files based upon delta information. The delta device can be a web server running delta software. It can store original files as either seed files or node files in a tree structure and store modifications to seed files and node files based upon the time and identity of the entity (e.g., user or computer) that requested or made such modifications.

Examples described herein relate to a method for maintaining high-availability of file system instances. Examples include maintaining replica file system instances such as a first replica file system instance on a first computing node and a second replica file system instance on a second computing node. Further, a third computing node is instructed to create a sparse replica file system instance on the third computing node in response to detection of a failure condition associated with the second computing node. Moreover, a data update request is directed to the first replica file system instance and the sparse replica file system.

An apparatus in one embodiment comprises at least one processing device comprising a processor coupled to a memory. The processing device is configured to identify a dataset to be scanned to generate a deduplication estimate for that dataset, to designate a subset inclusion characteristic to be utilized in the scan, and for each of a plurality of pages of the dataset, to scan the page, where scanning the page includes computing a polynomial-based signature for the page, determining whether or not the polynomial-based signature satisfies the designated subset inclusion characteristic, and responsive to the polynomial-based signature satisfying the designated subset inclusion characteristic, computing a content-based signature for the page and updating a corresponding entry of a deduplication estimate table for the dataset based at least in part on the content-based signature. The processing device generates the deduplication estimate for the dataset based at least in part on contents of the deduplication estimate table.