Abstract: A method of database update processing for updating efficiently database index keys, when new database index keys are supplied to replace index keys already in the database, generates a delta data between the new and old data comprising insert and delete keys by delete processing from a coupled node tree holding the index keys in the old data using index keys of new data as delete keys, and generates new data by delete and insert processing from and into a coupled node tree holding index keys in old data as index keys using the delete keys and insert keys of the delta data.

Abstract: To realize a high speed merge sort method by applying a coupled node tree, which method extracts a smallest or largest key from a plurality of sorted key storage areas in each of which is stored keys comprised of bit strings that are sorted, and generates a coupled node tree for merge while adding a processing source identifier that identifies the sorted storage area wherefrom the key has been extracted, and repeats the actions of writing out into the merged key storage area a key being obtained by a minimum or maximum value search on the coupled node tree and deleting the key, and inserting into the coupled node tree a key by extracting the key from one of the plurality of sorted key storage areas.

Abstract: Provided is a search method which is appropriate for handling a don't-care bit. A coupled node tree comprises a root node and a node pair, the node pair being a branch node and leaf node, or a pair of branch nodes, or a pair of leaf nodes located in adjacent storage areas. The branch node includes a discrimination bit position of a search key for the bit string search, which key is encoded so as to distinguish between don't-care bits and significant bits, and position information indicating a position of a primary node, which is one node of a node pair of a link target. A leaf node includes an index key which is a bit string in the status of either being or not being encoded.

Abstract: To provide a method that lessens the reduction in efficiency of processing using a coupled node tree even if the scale of the coupled node tree grows large. Is stored a termination node, whose discrimination bit position has a value smaller than 0, in a search path stack that holds the search history while successively storing therein branch nodes that have been traversed in the search path. The coupled node indicator of the stored branch node is converted to a value wherein a 1 is added if the link target is node [1].

Abstract: A coupled node tree comprises a root node and a node pair, the node pair being a branch node and leaf node, or a pair of branch nodes, or a pair of leaf nodes located in adjacent storage areas. The branch node includes a discrimination bit position of the search key and a position information of a primary node, which is one node of a node pair of a link target. The leaf node includes an index key that is a bit string that is the target of a search. A coupled node tree is searched using a longest-match/shortest-match search key and the longest-match/shortest-match node is determined through a comparison of the difference bit position between the index key resulting from the search and the longest-match/shortest-match search key and the discrimination bit position of a branch node on the search path memorized when the search is performed.

Abstract: A coupled node tree has a root node and a node pair, the node pair being a branch node, which includes position information of a link target node pair, and a leaf node, which includes a search target index key, or a pair of branch nodes, or a pair of leaf nodes located in adjacent storage areas. The nodes of the coupled node tree are backed up in a depth precedence search sequence. The coupled node tree is restored by repeating the following process: reading out the nodes in the sequence they are backed up, storing in a stack the position information of the node to be restored, successively restoring child nodes as long as branch nodes are encountered, restoring a leaf node which is read out and then, tracing back up the stack, a decision being made as to which node is next to be restored.

Abstract: A coupled node tree comprises a root node and a node pair, the node pair being a branch node and leaf node, or a pair of branch nodes, or a pair of leaf nodes arranged in adjacent storage areas. The branch node includes a discrimination bit position of the search key and the first position information of a primary node, one node of a node pair of a link target. The leaf node includes the second position information of the storage area holding an index key that is the target of a search. According to a bit value of the search key of a discrimination bit position in the branch node, repeated linking to a primary node of a node pair of the link target or a node at a position in a memory area adjacent thereto until a leaf node is reached.

Abstract: To provide a method that minimizes efficiency reductions in processing coupled node trees even if the size of the coupled node tree grows large. In basic searching or maximum or minimum value searching, the search history, not only the address information of the storage area wherein a node is stored but also the discrimination bit position of branch nodes traversed in the search path, is stored in the search path stack.

Abstract: A bit string searching apparatus has a coupled node tree, having a root node and a node pair, the node pair being a branch node and leaf node, or a pair of branch nodes, or a pair of leaf nodes in adjacent storage areas, the branch node including a search key discrimination bit position and information indicating a position of one node of a node pair of a link target, and the leaf node including an index key that is a bit string that is the target of a search, wherein a search for an index key from the root node to a branch node using a search key is executed by repeatedly and successively linking to one node of a node pair of a link target, according to a bit value of a search key at the discrimination bit position in the branch node, until reaching the leaf node.

Abstract: The minimum value or the maximum value of the index keys of a coupled node tree of a processing source is determined, and the index keys are successively deleted until the index key that is to be the splitting point is reached, the deleted index keys being inserted into the coupled node tree of the processing target, thereby splitting the coupled node tree. Deletion processing is done of one coupled node tree, taking as the processing source in the above-noted splitting method, and insertion processing is done of the other, taken as the processing target, thereby conjoining the coupled node trees.

Abstract: Bit string searching apparatus using a coupled node tree with a root node and a node pair stored in adjacent areas that is formed by a branch node and a leaf node, branch nodes, or leaf nodes; the branch node including a discrimination bit position in the search key and information indicating a position of a primary node that is one node of a node pair; the leaf node including an index key formed by a bit string; from the root node of an arbitrary subtree of the coupled node tree, linking is repeated based on the search key's bit value at the discrimination bit position and information indicating a position of a primary node until a leaf node is reached; an index key stored in the leaf node is obtained as a search result key of the subtree by means of the search key.