JPH0612550B2 - Data retrieval method - Google Patents

Description

Detailed Description [Summary] When searching data corresponding to each keyword, sub-keywords for each keyword are created in advance according to a certain rule and added to each keyword. Each time a request to search for the corresponding data by specifying is generated, the corresponding subkeyword is calculated based on the keyword based on the certain rule, and the target data is searched by the calculated subkeyword. This will shorten the data search time.

[Industrial application field]

 The present invention relates to a data search method.

Always access the database by specifying the desired keyword. For example, if the database is a telephone number, a desired person's name (keyword) is input to obtain the telephone number (data). Alternatively, if the database is a book catalog, for example, the desired book name or author name (keyword)
Enter to obtain the book catalog (data). The present invention relates to a data search method using such a keyword.

[Conventional technology]

In the conventional data search, keywords are compared character by character to detect whether or not they match a desired keyword. For example, in the above example, the person's name (provisionally "E
If the telephone number (data) corresponding to "MIKA" is read from the data table, first, EMIKA
Is converted for each character using ASCII code,
These are "45", "4D", "49", "4B", and "41". Then, among the keywords attached to each data in the data table, the keywords that match these "45" ... "41" are detected. In this case, the five characters are compared one by one. When a match is found here, the data (telephone number) is searched.

[Problems to be solved by the invention]

In the above-described conventional data search, a keyword of N characters (N is a natural number) is input to detect the same keyword in the data table. The number of characters of the keywords in the data table is different for each keyword, but in any case, the comparison operation corresponding to the characters of N characters of the input keyword is required at least N times. Therefore,
There is a problem that it takes a considerable time to access a target keyword, and eventually, it takes a long time to search for target data.

[Means for solving problems]

FIG. 1 is a diagram schematically showing the principle configuration based on the method of the present invention. In the figure, reference numeral 11 in the data search device 10 is a data table, which is, so to speak, a database. The data table has n data blocks 11-1,
11-2 ... 11-i ... 11-n. Each data block has the same structure, for example, data block 11-
i is shown in detail. The data block 11-i includes at least an area KEY-i of a normal keyword (KEY) and an area DATA-i of data (DATA) corresponding to the area KEY-i, which is a feature of the present invention.
The area key-i of y) is further added.

This sub-keyword key is for each keyword KEY,
It is generated in advance using the conversion unit 12 and added to the beginning of each data block (11-i).

On the other hand, when a data search request is made, the desired keyword KEY for access is input from the lower right of the figure. The sub-keyword k for access via the conversion unit 12
The data table 11 is converted by using this key.
Access each data block (11-i) in

[Work]

The conversion unit 12 for generating the sub-keyword key from the keyword KEY uses the keyword KE based on a certain rule.
A subkeyword ke having a bit length shorter than the bit length of Y
y is generated, and the access keyword KE
The sub-keyword for access and the sub-keyword area of each data block (11-i) are compared with the time for detecting a match / mismatch between Y and the keyword area (KEY-i) of each data block (11-i). (Key-i)
It takes less time to detect a match / mismatch with. That is, the data search time is shortened. The upper conversion unit 12 and the lower conversion unit 12 in FIG. 1 may be the same, or may be separate as long as the above-described certain rules are the same.

Subkeyword ke compared to the bit length of keyword KEY
Since the bit length of y is short, the number (i) of data blocks (11-i) that can be distinguished by the sub-keyword is naturally small. Therefore, one access sub-keyword k
There may be a case where two or more data blocks are accessed by ey. In this case, the keyword KE
The desired one is specified by checking the agreement / disagreement between Ys.

〔Example〕

2A and 2B are flowcharts showing one operation example in the conversion unit 12, which is a specific example of the above-mentioned "certain rule". According to the fixed rule according to this example, (a) the bit string representing the first character forming the keyword (KEY) is shifted by 1 bit in a fixed direction, and (b) the bit string shifted by 1 bit and the overflow by the 1 bit shift. 1-bit carry and second
The operation procedure of adding a bit string representing a character is used as one unit, and this is repeatedly executed for each character up to the final character.

According to the above-mentioned example (EMIKA), the operation as shown in FIG. 3 is performed. FIG. 3 is a diagram showing an example of a certain rule used in the present invention. Further, FIG. 4 is a diagram showing a simplified example of FIG.
The final result is the sub-keyword key (BA in this figure) for MIKA). In FIG. 3, for the first character (E of the first character) W1, the addition bit string (ADO) to be added to this is also carry (CR).
O) does not exist, so both ADO and CRO are preset to 0. Therefore, the added bit string AD1 for the first character W1 is the first character W1 itself.

Next, AD1 is bit-shifted (left-shifted) to obtain a carry CR1 (0 in this case), and a bit string AD1 ′ shifted by 1 bit is obtained.

These CR1 and AD1 'are the second characters W2 (EMIKA
(Indicating M of the above) is added to obtain an addition bit string AD2. A
D2 is further shifted by 1 bit to obtain AD2 ', and at the same time, carry CR2 (1 in this case) which overflows is obtained.

AD2 'and CR2 are added to the third character (I in EMIKA) W3, and the same operation is sequentially repeated until the final character (A).

The above operating procedure is illustrated in flow chart form in FIGS. 2A and 2B.

To make it easier to understand (by ASCII code), the fourth
As shown in the figure, the final result BA is the subkeyword key for the keyword KEY (EMIKA).
Obtained as. Unlike FIG. 3, FIG. 4 shows the addition of each value (ADO, CRO, W1 ...) As a flow from left to right and from upper to lower.

Although the above-mentioned certain rule is an example, it is confirmed by simulation that the matching rate is considerably low.
The matching rate is the number of keywords that are accessed redundantly by one sub-keyword, and it is natural that the smaller the number, the better.

〔The invention's effect〕

As described above, according to the present invention, a keyword for 5 bytes is conventionally inspected 5 times for each byte (for each character), but is converted into a 1-byte sub-keyword according to a certain rule. I try to do it only once. Therefore, the corresponding data block can be accessed at high speed. In this case, one sub-keyword may be used to access two or more keywords KEY, but only at that time, the original keywords may be matched.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing the principle configuration based on the system of the present invention, FIGS. 2A and 2B are flow charts showing one operation example in the conversion unit 12, and FIG. FIG. 4 is a diagram showing an example, and FIG. 4 is a diagram showing the example of FIG. 3 in a simplified manner. 10 ... Data retrieval device, 11 ... Data table, 11-1, 11-2 to 11-i to 11-n ... Data block, 12 ... Conversion unit, KEY ... Keyword, key ... Sub-keyword, D
ATA ... data.

Claims (1)

[Claims] 1. A data block (11) comprising a keyword area (KEY-i) (i is a natural number 1, 2, 3, ...) And a corresponding data area (DATA-i). -
In a data retrieval device for reading desired data (DATA) corresponding to the access keyword (KEY) by externally accessing the data table (11) having a plurality of i) with the access keyword (KEY) , Each data block (11-i) has a structure in which a sub-keyword (Key) area (Key-i) is further added to the head of the data block, and each sub-keyword ( Key) is pre-converted into a word having a bit length shorter than each keyword (KEY) according to a certain rule and written in the area (Key-i) of the sub-keyword (Key). , The access keyword (K
EY) is input, the corresponding sub-keyword (Key) corresponding to the same fixed rule as the fixed rule is input.
After the conversion, each data block (11-i) is accessed, and the same sub-keyword (Key) as the converted sub-keyword (Key) is added to the beginning of the data block (11-i). The desired data (DATA) is read out from the data area (DATA-i) of, and the same sub-keyword (Ke
The data block (11-i) with y) added at the beginning is 2
When there is the above, the data block (KEY-i) of each of the two or more data blocks is accessed, and the data block (KEY) having the same keyword (KEY) as the access keyword (KEY) is accessed. 11-i) is detected and the desired data (DATA) is read out.