A computer memory compression method involves analyzing (1210) computer memory content with respect to occurrence of duplicate memory objects as well as value redundancy of data values in unique memory objects. The computer memory content is encoded (1220) by eliminating the duplicate memory objects and compressing each remaining unique memory object by exploiting data value locality of the data values thereof. Metadata (500) is provided (1230) to represent the memory objects of the encoded computer memory content. The metadata reflects eliminated duplicate memory objects, remaining unique memory objects as well as a type of compression used for compressing each remaining unique memory object. A memory object in the encoded computer memory content is located (1240) using the metadata (500).

Techniques and solutions are described for compressing data and facilitating access to compressed data. Compression can be applied to proper data subsets of a data set, such as to columns of a table. Using various methods, the proper data subsets can be evaluated to be included in a group of proper data subsets to be compressed using a first compression technique, where unselected proper data subsets are not compressed using the first compression technique. Data in the data set can be reordered based on a reordering sequence for the proper data subsets. Reordering data in the data set can improve compression when at least a portion of the proper data subsets are compressed. A data structure is provided that facilitates accessing specified data stored in a compressed format.

Page filtering in a database using a compression dictionary. A page of a database table is compressed, creating a compression dictionary. The compression dictionary includes entries with a byte sequence from the page and a compression symbol associated with the byte sequence. A part of the compressed page, the compression dictionary, and a page symbol list with compression symbols from the dictionary present in the part of the page, are received. A query having a predicate with a predicate value is received. A predicate symbol list, including symbols in the dictionary whose byte sequences at least partially match the predicate value, is generated. Based on the predicate symbol list and the page symbol list, it is determined that at least one symbol from the predicate symbol list is also present in the part of the page. The query is performed by evaluating the predicate on the part of the page.

To produce output from a memory block, a first index is used to access a pointer, a mode select and a function select from a first memory. The pointer, the mode select and the function select are used to produce a second index. The pointer is used to produce the second index when the mode select is a first value. A function is used to produce the second index when the mode select is a second value. The function select identifies a function to be used to produce the second index. The second index is used to access output from a second memory.

In various examples, metadata may be generated corresponding to compressed data streams that are compressed according to serial compression algorithms—such as arithmetic encoding, entropy encoding, etc.—in order to allow for parallel decompression of the compressed data. As a result, modification to the compressed data stream itself may not be required, and bandwidth and storage requirements of the system may be minimally impacted. In addition, by parallelizing the decompression, the system may benefit from faster decompression times while also reducing or entirely removing the adoption cycle for systems using the metadata for parallel decompression.

An information handling system for compressing data includes a data storage device and a processor. The data storage device stores a dictionary and an uncompressed data block. The processor prepends the dictionary to the uncompressed data block, determines, from the uncompressed data block, a literal data string and a match data string where the match data string is a matching entry of the dictionary, and compresses the uncompressed data block into a compressed data block that includes the literal data string and an offset pointer that points to the matching entry.

An context-based encoding mechanism uses a predetermined number of bytes in a previous segment of a file to determine a context for the current segment. The current segment is encoded using a dictionary that corresponds to the determined context. An example method includes determining, for a first segment in a data file, a first context state based on a first context segment within the data file that precedes the first segment, identifying a first indexed dictionary from a plurality of indexed dictionaries based on the first context state, and encoding the first segment using the identified first indexed dictionary.

Broadly speaking, embodiments of the present technique provide methods, apparatuses and systems for controlling device resource subscriptions by an LwM2M server, comprising receiving at said LwM2M server a registration request message from a LwM2M client device, the message comprising an enumeration of a plurality of subscribable elements of an object hierarchy of the device; storing, using the LwM2M server, an association between the device and the plurality of subscribable elements; and sending from the LwM2M server to the LwM2M client device a subscription message comprising a unitary compressed expression representing plural ones of said plurality of subscribable elements associated with said device.

A method, computer program product, and system includes a processor obtaining data including values and generating a value conversion dictionary by applying a parse tree based compression algorithm to the data, where the value conversion dictionary includes dictionary entries that represent the values. The processor obtains a distribution of the values and estimates a likelihood for each based on the distribution. The processor generates a code word to represent each value, a size of each code word is inversely proportional to the likelihood of the word. The processor assigns a rank to each code word, the rank for each represents the likelihood of the value represented by the code word; and based on the rank associated with each code word, the processor reorders each dictionary entry in the value conversion dictionary to associate each dictionary entry with an equivalent rank, the reordered value conversion dictionary comprises an architected dictionary.

Accesses between a processor and its external memory is reduced when the processor internally maintains a compressed version of values stored in the external memory. The processor can then refer to the compressed version rather than access the external memory. One compression technique involves maintaining a dictionary on the processor mapping portions of a memory to values. When all of the values of a portion of memory are uniform (e.g., the same), the value is stored in the dictionary for that portion of memory. Thereafter, when the processor needs to access that portion of memory, the value is retrieved from the dictionary rather than from external memory. Techniques are disclosed herein to extend, for example, the capabilities of such dictionary-based compression so that the amount of accesses between the processor and its external memory are further reduced.