Hitachi, Ltd.

Nobuhiro Taniguchi

Akira Yamamoto

Masashi Tsuchida

Hiroyuki Kitajima

Tadashi Ohsone

Yoshiaki Yamashita

Hiroki Yamashita

Minoru Yamada

Hirotoshi Tanaka

Kenji Nagai

Kazuhiko Ohmachi

Kazuhiro Satoh

Atsumi Kawata

Shinichi Fukushima

A shift register 10 receives serial data and outputs parallel data in synchronism with the timing of the serial data received. A shift register group 20, 21 receives bit outputs of the parallel data from the shift register 10. The number of bits of shift registers 20, 21 in the shift register group is set in a certain condition that corresponds to the bit outputs of the parallel data from the shift register 10. A plurality of coincidence circuits 107, 108 are provided, which detects agreement between a preset data starting pattern and the bit arrangement of the data in the shift register group. A selector 306 selects a set of parallel outputs from the shift register group according to the output signal from the coincidence circuits 107, 108. Thus only the shift register 10, performs high-speed operations at the same timing as the received serial data, and the other circuits operate at slower speeds whose timing is several times longer than that of the serial data received, thereby eliminating complex timing and averting difficulty control logic.

Serial to parallel data converting circuit

A set of sorted columns of one table stored in a DB machine are binary-searched by a hardware in synchronism with data transfer when another table is read from a disk unit, to select a row to be joined. Where a key word sequence to be searched is stored in ascending or descending order, determination of a maximum address in an area in which key words smaller than a search key are stored and determination of a maximum address in an area in which the key words smaller than or equal to the search key are stored are parallelly executed to determine the store range in one searching.

Method and apparatus for processing data base

A skip table is prepared from which a state of a subsequent symbol string and an address of one or plural symbols to be subsequently inputted can be readily determined by making reference to a set of a current symbol string search state and one or plural symbols to be subsequently inputted of the symbol string. When executing searching for the symbol string, data stored in the skip table are looked up to assure the symbol string search by inputting only a minimized number of necessary characters of the symbol string. Necessity of inputting all the characters of the symbol string for searching is eliminated and the processing speed can be increased considerably. A plurality of symbol strings may be searched for.

Method and apparatus for retrieval of a search string

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Hadano, Japan

Nobuhiro Taniguchi