DE102015222095A1 - Method and device for delta encoding a database - Google Patents

Abstract

Method (10) for delta encoding a dataset, characterized by the following features: - a reference version and a comparison version of the dataset are subjected to a common transformation (11) such that a version of common data area of the dataset, which in the comparison version of a shift the reference version has identical values in the transformed versions, - the values are used to construct a search index (12), - the reference version is searched for the data area by means of the search index (13) and - the differential coding comprises those searched (13) quantified shift.

Description

The present invention relates to a method for the delta coding of a database. The present invention also relates to a corresponding device, a corresponding computer program and a corresponding storage medium.

State of the art

Methods are known for distributing or updating software via a wireless data interface, sometimes referred to as an over the air (OTA). Generic methods apply to both application software (SOTA) and embedded system software (firmware, FOTA).

In EP 1516292 A1 For example, a method and a device for a vehicle-related telematics service are proposed, wherein the same application protocol is used for the telematics service both for the air interface and for the communication within the vehicle and possibly within the service center.

Also known as delta encoding or differential storage is a method of data compression, which is used for space-saving storage of correlated data - such as sequential versions of software - by way of so-called decorrelation.

According to WO 2000008616 A1 For example, in a device for coding and decoding locations in a traffic route network, to which information is transmitted from a transmitter to a receiver, it is provided that the code consists of an agreement part and each encoded location of a coordinate part that the coordinate part more Coordinate pairs containing a pair of coordinates the coded location coordinates stored on the transmitter side and at least one additional coordinate pair at least one auxiliary point that the agreement part at least the number of coordinate pairs contained in the coordinate part, the location of the coordinate pair of the coded location in the coordinate part and an indication of the type of the coded location and, for decoding, that in a location database containing the coordinates, the location on each traffic route and further information of locations, locations are determined which are within the tolerance ranges of the received n pairs of coordinates lie, that those are selected from the determined locations, which are located on a common traffic route, and that from the selected locations that is determined to be decoded, which lies within the tolerance range of the particular coordinate pair. To reduce the amount of data to be transmitted, the respective difference to the first pair of coordinates (delta coordinates) can be transmitted for the further pairs of coordinates.

Disclosure of the invention

The invention provides a method for delta encoding a database, a corresponding device, a corresponding computer program and a corresponding storage medium according to the independent claims. The term "data" is to be understood in a broad sense for the purposes of the following statements, and includes, for example, structured binary data as well as executable or interpretable program code in any programming language.

In this method, the data is subjected to a transformation in a first step. This transformation is designed so that the transformed data are identical, even if the original data itself is modified by local changes. In particular, executable program code consists of areas that define an action or operations - collectively referred to in the claims as "instruction codes" - and areas that contain constant values, addresses or register addresses - collectively referred to in the claims as "parameters". An advantageous transformation here is the masking out of values, addresses and register addresses, since these change to varying degrees.

In these data transformed according to the invention, a fast indexed search is possible, so that the processing effort drops dramatically compared to a delta coding according to the prior art.

This technique according to the invention thus makes it possible to extend the search range to the search in the entire data area of the overall system. As a result, in addition to the delta between two files, further reduction can be achieved through deduplication, ie the finding of identical or similar areas in the overall database. These areas then need not be coded several times separately in the delta data, but can be coded in a space-saving manner by references to this area or references in conjunction with the differential data described below. Register data and constants can be used in this context from different sources for updating.

Changes sometimes lead to shifts in the executable code. This conditionally under Circumstances Changes to jump destinations or jump distances for program branches. If deduplication is used to reduce the amount of data, the jump destination may be in an area that has its source in another file. Thus, no usable shift information is available. In a method according to the invention, a signature is formed from the data at the jump destination instead. Then the next occurrence of this signature is determined in the new version and the jump target is changed to it. Thus, no data in the delta information is required for this update. In the same way as for the jump destinations, the changed addresses for data can be updated efficiently, as well as changes to symbol tables can be coded efficiently. Jump destinations, addresses and changes are therefore referred to in the claims simplifying as a "pointer". This applies in the same way to load addresses for constants.

Other changes to the code are coded in a method according to the invention by dividing the code into areas defining an operation and areas containing constant values, addresses or register addresses. These values often change only slightly and can be efficiently compressed in the form so extracted.

Furthermore, in such extracted data dependencies can be determined among each other and efficiently transferred in a common change information memory efficient. For example, a typical change is that in successive instructions, one register is replaced with another register. Rather than transmitting change information for each occurrence of this change, only change information is used to update all registers in an area in the recognized manner.

The measures listed in the dependent claims advantageous refinements and improvements of the independent claim basic idea are possible.

Brief description of the drawings

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. It shows:

1 the flowchart of a method according to a first embodiment.

2 schematically a device according to a second embodiment.

Embodiments of the invention

1 illustrates the flow of a method based on a simplified flowchart 10 according to an embodiment of the invention. In order to reduce the required amount of data, dependencies on changes at various points of the data are recognized and summarized to a change information.

The transformation 11 is advantageously implemented for executable code as a separation of the bits defining the type of operation from the bits defining data.

In an advantageous embodiment, the signature for the identification of jump destinations and data addresses from a range of data or by way of transformation 11 transformed data itself exist.

In order to reduce the amount of data required for updating, only information on the existence and nature of this dependency is stored in the difference information for data areas which depend on other data areas. The dependent changes are then generated in the target system according to predefined rules or rules contained in the difference information. Advantageously, this can be applied to a program loading table. In executable and linkable format (ELF) files, this area is marked as section .plt. The program load table contains references to an object table ("section .got"). In the process 10 The entire range of the program load table is generated from the starting point of the references without any further update information in the target system. The starting point of the references is also obtained from the header information of the file, if it is an ELF format file. Likewise, other areas that depend on other areas will be reconstructed in their new form without further information from these pending areas. An example of this is a hash table that depends on the data of a symbol table. Instead of transferring change information for the hash table, the hash table from the new symbol table is generated in the device to be updated and the sorting of the symbol table is derived from it.

This method 10 For example, in software or hardware or in a hybrid of software and hardware in one device 20 be implemented as the schematic representation of 2 clarified.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1516292 A1 [0003]
• WO 2000008616 A1 [0005]

Claims (10)

Procedure ( 10 ) for the delta coding of a dataset, characterized by the following features: a reference version and a comparison version of the dataset are subjected to a common transformation ( 11 ) in such a way that a version of the common data area of the dataset, which in the comparison version is subject to a shift from the reference version, has identical values in the transformed versions, - a search index is constructed from the values ( 12 ), - the reference version is searched for the data area based on the search index ( 13 ) and - the differential coding comprises those through the search ( 13 ) quantified shift. Method according to claim 1, characterized by the following features: the reference version and the comparison version comprise a plurality of files, the browsing ( 13 ) takes place across files in such a way that similar or identical areas are found in the files and - the differential coding comprises references to the areas. Method according to Claim 1 or 2, characterized by the following features: the database comprises executable program code, the program code comprises command codes and parameters, the transformation 11 ) comprises extracting the parameters from the program code, - the extracted parameters are compressed and - the differential coding comprises the compressed parameters. Method according to one of claims 1 to 3, characterized by the following features: The parameters include pointers to data in the program code, - a signature is formed from the data, - In the comparison version, a nearest occurrence of the signature is determined and - The pointer is changed to the determined occurrence. Method according to claim 4, characterized by at least one of the following features: The pointers indicate jump destinations, - the pointers denote addresses or - The pointers denote symbols of the program code. Method according to one of claims 3 to 5, characterized by the following features: - Mutual dependencies of the extracted parameters are determined, - the dependencies are transferred to a common change information and - The differential coding includes the change information. Method according to claim 6, characterized by the following feature: The dependencies relate to a register designated by the parameters in a consistent manner. Computer program, which is set up the procedure ( 10 ) according to one of claims 1 to 7. Machine-readable storage medium on which the computer program according to claim 8 is stored. Contraption ( 20 ), which is set up, the procedure ( 10 ) according to one of claims 1 to 7.

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