Abstract: A data processing device (DPD) comprises a main memory (MM) and a processing means (PM). Data from a data base system (DBS) is stored as pages in the main memory (MM). During processing of the individual objects (OB) of the pages (P) the access frequency to each object (OB) stored in the main memory (MM) is determined. Objects having similar access frequencies are collected in the same data storage section of the main memory (MM). In particular, data objects (OB) can be moved to higher order data storage sections to which a higher access frequency range has been assigned. Thus, data which is more frequently used by the processing means (PM) stays in the main memory (MM) longer and data objects which are not so frequently used are transferred back to the data base or are overwritten earlier.

Abstract: The present invention relates to a method of regulating the load in a distributed database (A), where the information within the database is distributed between several different nodes (1, 2, 3, . . . , k) belonging to the database. A request (4a) from a user (4) is served either by the node to which the user connects, here designated the receiving node (1), or by some other node after the receiving node (1) has forwarded the request to a node that can meet the request, this node being called the serving node (2). Respective nodes are given one or several key-numbers which limit the number of requests that respective nodes may accept in their role as a receiving node (1). The key-numbers are related to the executing capacity of the database (A).

Abstract: The present invention relates to a method of storing elements in a database and of finding such stored elements. A reference to a storage space intended for the storage of a data element in the database is calculated by means of a mathematical function, wherein the function input data is an external key belonging to the element, and wherein the result obtained with the mathematical function points to an internal position of the element in the database. The result is divided into at least three parts (A, B, C). A first part (A) constitutes a reference to a fragment (A4) belonging to the database, a second part (B) constitutes a reference to a page (B4) within the fragment (A4), and a third part (C) constitutes a reference to a so-called bucket (C4) belonging to the page (B4). A bucket (C4) is comprised of at least one container in which the element can be stored, or is stored.

Abstract: The present invention relates to a method of handling the risk of a deadlock between simultaneous transactions T1, T2 in a database 1. The method is based on allocating to respective objects 01, 02 in the database 1 a lockout queue L1, L2 in which transactions T1, T2, T3, . . . , T8 that request access to an object 01, 02 are placed to await the access to said object of a preceding transaction. The handling procedure comprises going through, or perusing, the lockout queues L1 belonging to different objects 01 to detect so-called locking transactions T1 that can cause a deadlock and, subsequent to detection, comparing said locking transaction with other transactions T2, T6, T1. T7, T8 in other lockout queues L2 therewith enabling the risk of deadlock between a first and a second transaction T1, T2 that have both requested access to the same first and second object 01, 02 to be detected.

Abstract: A method of dealing with inquiries for data-information within a network is presented. A cache, which includes a number of nodes, acts within the network. Data-information may be stored in any of the cache nodes and may be available for a given period of time. The cache nodes are arranged in a hierarchical node tree structure. This tree structure includes a plurality of object nodes, a plurality of directory nodes, and a root node. The root node constitutes the root of the tree structure and the object nodes are positioned furthest out in the tree structure. All data-information is stored within object nodes. Any intermediate levels between an object node and the root node are comprised of directory nodes. The directory nodes and the root node include a directory that covers all data-information stored within object nodes that are located beneath the node in the tree structure and within which object node respective data-information is stored.

Abstract: The present invention relates to a method pertaining to databases and intended to provide reliable collection of log-information in connection with changes in the database. So-called fuzzy check-points are used in combination with a physiological log with the intention of enabling log-information to be collected in real time. The data-information belonging to the database is divided into smaller parts in accordance with a predetermined data-structure, where respective parts are distributed on mutually the same pages or on separate pages belonging to the database. The logical UNDO-information required for the fuzzy check-point is implemented through the creation of a further part (1′) on one of the pages, in the event of a change of one of the parts (1) where old data-information shall be replaced with new data-information. This further part (1′) is structurally a replica of the changed part (1).

Abstract: The system relates to a structure for the storage of data-information within a data-base, which information is structured into a hierarchy of nodes and which hierarchy consists in a tree-structure. This tree-structure has a root-node (1), possibly one or several intermediate nodes (2, 3) and one or more leaf-nodes (4), wherein the root-node (1) comprises one or more root-elements (1E), wherein respective intermediate nodes (2, 3) include one or more intermediate elements (2E1, 2E2, 2E3, . . . ), and wherein respective leaf-nodes (4) include one or more leaf-elements (4E1, 4E2, 4E3, . . . ). Respective elements include the address information necessary to hold the tree-structure together and enable searches to be performed in the tree and data-information.

Abstract: The present invention relates to a method of performing a transaction that affects several nodes within a system of nodes in which information belonging to a distributed data-base is stored. The transaction originates from a transaction coordinator (1) and affects at least one group of nodes which comprises a first node (n1), a second node (n2) separate from the first node (n1) and possible intermediate nodes (n3) which comprise further nodes that are separated from one another and from the first and the second node.

Abstract: The present invention relates to a method of performing a schema change within a data-base, where the schema change is a complicated schema change, such as a complicated soft schema change, which results in the compatibility of a first schema version, before the schema change, with a second schema version, after the schema change, or a complicated hard schema change which renders a first schema version, before the schema change, incompatible with a second schema version after the schema change. The execution of a schema change is, according to the method, divided into a number of phases (1, 2, 3, 4, 5). According to one embodiment, a schema change is divided into three phases, a preparatory phase (1), a scanning phase (2), and a terminating phase (3). According to another embodiment, two further phases may be carried out between the scanning phase (2) and the terminating phase (3). These further phases are an evaluating phase (4) and a decision phase (5).

Abstract: The present invention relates to a method to of ensuring the reliability of a system distributed data base, comprising several computers which together form nodes (1, 2, 3, 4) wherein information belonging to the distributed data base is storable. A fragment comprises a part of the data base and includes a primary replica (11) of the part and a secondary replica (21) of the part. The primary replica (11) is stored within a first node (1) and the secondary replica (21) is stored within a second node (2), separated from the first node (1). Both data information and log information are stored within both the primary replica (11) and the secondary replica (21). The secondary replica (21) is updated when the primary replica (11) changes (A) and is used to re-create a primary replica should the first node (1) crash. Respective fragment also comprise a stand-by replica (31) of the part, which is stored in a third node (3) that is separate from the first (1) and the second (2) node.