JPH02297669A - Managing method for sequential file with index - Google Patents

Abstract

PURPOSE:To retrieve data at high speed by finding key according to link information to improve the priority order of an order to retrieve data, which are frequently retrieved, and retrieving the data when the data are retrieved according to a condition besides the key to a regularly programming (ISAM) file. CONSTITUTION:A key file 02 is referred as an weighing file at first and a number value in a highest priority order key block No2-1 is calculated. Then, the key housed in a key block KB corresponding to the number value is designat ed and a retrieval request is outputted to the system of an ISAM file 01. After wards, the reading of data 1-7 is executed. When the data 1-7 are not the objec tive data, the retrieval is requested by a key K in the key block KB of the second priority order retroactively to a key block number No (index showing which number the key is) 2-5 of the second priority order in the key block KB. Thus, the data to be retrieved can be retrieved at high speed.

Description

[Detailed description of the invention] [Industrial application field]

A key that can uniquely identify this searched data is added to the searched data written in random order, and records as data to which this key is added are arranged so that the values of the keys are in ascending order. In a system for indexed sequential files (hereinafter also abbreviated as ISAM files) that enables high-speed searching of the searched data, there is a search system that enables high-speed file searching based on conditions other than keys. This article relates to a method of managing sequentially organized files. Note that in the following figures, the same reference numerals indicate the same or corresponding parts.

[Conventional technology]

The ISAM file system is a file system that is managed in units of records, which are created by adding search data called keys to search target data. The key has an alphabetical order and is unique because it has the purpose of uniquely identifying the record. The records are stored in the ISAM file in the order of this key, and if you want to search for the data to be searched, and therefore the record, just specify that key, and the rest is done in the ISAM file.
The file system will automatically search for it.

[Problem B that the invention attempts to solve]

However, when using this ISAM file system, it is good when you clearly know the key of the target record, but it is not effective when you want to search based on the contents of the searched data in the record. The content of the searched data must be determined by specifying the key and reading it each time. In this case, you would normally specify the first key and then search by increasing the keys one by one. Therefore, if the target record is the last key, records for all keys must be read, which causes a problem that the time required for the search increases accordingly. Furthermore, if frequently used records are located near the end, there is a problem in that the load on the system becomes extremely large. Therefore, the present invention weights the key according to the later date of the search time, or provides link information in the searched data other than the key in the record to identify the later date of the search time of the data. It is an object of the present invention to solve the above problem by providing a method for managing indexed sequential files in which data searches are performed using weighting information or link information.

[Means to solve the problem]

In order to solve the above-mentioned problems, the method of the present invention adds a key (such as K) that can uniquely identify the searched data (such as DT) written in random order to the searched data (DT, etc.). An indexed sequential file (such as 01) in which records as data with keys (such as 1-4) are arranged in ascending order of the key values, and the data to be searched can be searched at high speed. ) system, by providing a file (key file 02, etc.) that stores weights for keys in addition to the existing indexed sequential file, and making it possible to search the searched data according to this weighting information. , 1 so that the searched data can be searched at high speed based on conditions other than the key.
Or, add a key that can uniquely identify this searched data to the searched data written in random order, and arrange the records as data with this key in ascending order of the values of the key. In an indexed sequential file system in which the data to be searched can be searched at high speed by arranging the searched data as shown in FIG. -1, previous priority key 6-2, etc.), and by making it possible to search the searched data according to this link information, the same searched data can be searched at high speed based on conditions other than the key. 1 so that it can be searched.

[For use]

The present invention provides search target data of existing ISAM files.
In order to give search priority, a function that gives weight according to when the records in the file (therefore the searched data) were searched, that is, records with keys that have been accessed recently are given the highest priority. IS
It is recommended to provide a function to change the key link (search order) of this weighting file (key file) every time the AM file is accessed, or to search data other than the key of the record of the existing ISAM file. Provide link information that determines when the record (and therefore the searched data) was processed, that is, information that gives the record with the most recently accessed key the highest priority and first in the search order. By replacing this link information each time each record is accessed, it is possible to search for records in the order in which they were most recently accessed. This makes it possible to minimize the load placed on the system when searching for records, without making any changes to the existing ISAM file record arrangement, even if frequently used records are near the end. become.

【Example】

The present invention will be described in detail below with reference to FIGS. 1 to 9. First, FIG. 9 is a structural diagram of file 01 of the ISAM file system. That is, ISAM file 01 has index blocks 1-2, data blocks 1-3,
It is composed of three types of blocks: empty block 1-1. Index block 1-2 is data block 1-
This part manages the connection of data blocks 1 to 3, and is composed of block numbers BN indicating the numbers of data blocks 1 to 3. The data block 1-3 includes a plurality of records 1-4, the block number BN, and link information LD between the block numbers BN of each data block 1-3. Also, the structure of each record 1-4 is fixed length, and this record 1-4 has a fixed length.
-4 is data 1-7 consisting of the searched data DT as the final search target, a key that can uniquely identify the data DT, etc., position information 1-5 for the key, and the key 1-4. 7, data length (key length) 1-6. Then, this ISAM file system determines the connection between data blocks 1-3 based on this key K, and configures the array of block numbers BN that constitute index block 1-2 and data blocks 1-3. The arrangement of records 1-4 is changed so that the keys K are in ascending order. Next, a first embodiment of the present invention will be described based on FIGS. 1 to 4. In this first embodiment, a key file 02 as a weighting file having a structure as shown in FIG. 2 is prepared in addition to the above-mentioned ISAM file 01. Koki key file 0
2 is data 1 stored in ISAM file 01
This is a file that defines the priority order of keys in -7.
It consists of a leading part 02+1 and a large number of key blocks KB corresponding to each record 1-4. And the first part 02)1
has the highest priority key block Nα2-1, key length 2
-2, key K, and therefore the number of key blocks KB 2-3 are registered. Each subsequent key block KB contains each key K.
(Contents of), next priority key block Nα2-5, and previous priority key block Nα2-6 are stored. Next, an outline of a method for searching for the target search data DT using these files 01 and 02 will be explained using FIG. First, in an application program, if you want to search for target data using conditions other than keys, conventionally, you would first specify it as the first key, read data 1-7, read the information DT in data 1-7, It is determined whether the searched data DT is the target data. This process is repeated to search for the desired data. Here, if this data 1-7 is searched frequently, the same amount of time will be spent each time. In the present invention, first, the key file 0 as a weight scale file is
2, find the number value within the highest priority key block distance 2-1, and select the key block KB corresponding to that number value.
ISAM file 01 by specifying the key stored in
sends a search request to the system and reads data 1-7. If the data 1-7 is not the desired data, follow the link of the next priority key block N11 (index indicating the key number) 2-5 of the key block KB, A search is requested using the key K in the next priority key block KB. For example, this process can be performed using the key block KB in the key file 02 in the same figure.
Repeat steps from ■ to ■ to search for the desired data. When the search for the target data 1-7 (therefore the searched data DT) is completed, the record 1-7 with the key K is
A process of assigning the corresponding key block KB of the key file 02 corresponding to No. 4 to the highest priority is performed. Next, the procedure for this attachment change process will be explained using FIG. 3. This figure compares changes in the link information in the leading part 02H9 of the key file 02 and in the key block KB before and after the above-mentioned search. First, the previous priority key block No. 2- of the key block KB searched this time (number value Nα4-1 in this example)
6 (No, 4-2 in this example) and the number value Nα4-3 in the next priority key block Nα2-5 are checked, and the previous priority key block KB (Nα
The number value Nα4 of the next priority key block KB in the next priority key block Nα2-5 in 4-2)
-3, and conversely the next priority key block K
Previous priority key block N in B (No, 4-3)
o, 2-6 contains the previous priority key block K
The number value Nα4-2 of B is stored. Also, the highest priority key block KB (number value No.
, 4-4), the previous priority key block Nα2
The number value Nα4-1 of the keep lock block KB searched this time is stored in −6, and the next priority key block Nα2-5 of the key block KB searched this time (Nα4-1) is stored in the previous key block Nα2-5. The number value No. 4-4 of the highest priority key block KB is stored, and the corresponding key block Nα4- is stored in this key block (No. 4-1). A special mark indicating that 1 is the highest priority is stored.After that, the highest priority key block No. at the top of the key file 02) 1, the number value No. of the key block Nα for the record currently searched in 2-1, Write 4-1. Furthermore, when new data is added to the ISAM file 01, it must be registered in the key file 02 as well. Next, this registration procedure will be explained using the fourth example. The figure shows the first part 02H of the key file 02,
and a comparison of changes in link information in the key block KB before and after this addition. The key block KB to be added this time (number value Nα5
-1) previous priority key block N012
-6 stores a special mark indicating that the key block KB of this key block has the highest priority, and the next priority key block Nα2-5 of this key block stores the previous highest priority. The number value of the key block KB (Nα5-2 in this example) is stored. Next, the number value Nα5-1 of the key block KB to be added this time is stored in the previous priority keep lock Nα2-6 in the key block KB with the number value Nα5-2 as the key block with the highest priority up to now. Then, the number value 5-1 of the key block added this time is stored in the highest order key block Nα2-1 at the beginning 02H of the key file 02. Next, a second embodiment of the present invention will be described based on FIGS. 5 to 8. In the second embodiment, a data section 1-7 having a structure as shown in FIG. 6 is provided in records 1-4 of the rsAM file 01 described in FIG. 9. That is, in this data section 1-7,
In addition to the key, a next priority key 6-1 and a previous priority key 6-2, which are two pieces of link information having the same length as the key, are added to the head of the conventional searched data DT. Then, the DTI becomes the data to be searched. And further ISAM
Separately from file 01, a leading key file 03 is provided as a file that stores keys K of records 1-4 that have been accessed most recently. An outline of a method for searching for target data using the leading key file 03 and the above-mentioned link information of the data section 1-7 will be explained with reference to FIG. First, if you want to frequently search for target data using conditions other than keys in an application program, first refer to the first key file 03,
Find the key with the highest priority, specify that key K, and press I
A search request is issued to the SAM file system 01, and reading of data 1-7 (therefore, DT) is executed. Here, if the read data 1-7 is not the target data, the next priority key 6-1 in the record 1-4 is
A search request is made to the ISAM file system 01 by following the link of the key number in the file and specifying the indicated key K. This process is repeated to search for the target data 1-7. When the search for the target data 1-7 is completed in this way, the priority order of the record 1-4 having the key K is changed.The procedure will be explained using FIG. do. FIG. 7 shows changes in the link information in the leading key file 03 and records 1-4 before and after this search. First, the record with the key number value (Nα7-2 in this example) stored in the previous priority key 6-2 in the record 1-4 searched this time (its key number value is Nα7-1) 1-4, and record 1 with the key number value (Nα7-3 in this example) stored in the next priority key 6-1.
-4 and next priority key 6 in record 1-4 with number value 7-2 of the previous priority key.
-1 is the number value No. of the next priority key, 7-3
and conversely the number value Nα7- of the next priority key.
Previous priority key 6-2 in record 1-4 with 3
The number value Nα7-2 of the previous priority key is stored inside. Also, records 1-4 (in this example, the key number value No.,
Store the number value Nα7-1 in the key of the record currently searched in the previous priority key 6-2 in 7-4), and store the number value Nα7-1 in the key of the record currently searched (key number value 7-1). In the next priority key 6-1, the number value No. 7-4 of the highest priority key up to the previous time is stored, and in the same way, in the previous priority key 6-2, the corresponding record 1-4 is stored. Stores a special mark of highest priority. Thereafter, the key number value Nα7-1 of the record 1-4 retrieved this time is written into the first key file 03. Furthermore, when new data is added to the ISAM file 01, it must be registered in the leading key file 03. This procedure will be explained using FIG. 8. The figure shows the first key file 03 before and after this addition.
and changes in link information in records 1-4. In other words, a special message indicating that this record has the highest priority is added to the previous priority key 6-2 in record 1-4 (in this example, the key number value is Nα8-1) that is to be added this time. The mark is stored, and the number value of the highest priority key up to the previous time (in this example, NQ, 8-2) is stored in the next priority key 6-1 of the record. Next, the previous priority key 6 in the record 1-4 with the key number value Nα8-2 stored in the first key file 03
The key number value Nα8-1 to be added this time is stored in -2.

【Effect of the invention】

According to the present invention, when searching for data in an ISAM file using conditions other than a key, the data is searched by following link information that increases the priority of the search order for frequently searched data. By doing this, data can be searched quickly.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of a data search method as an embodiment of the present invention, Figure 2 is a configuration diagram of the key file in Figure 1, and Figure 3 is the processing procedure for the key file after data search in Figure 1. FIG. 4 is an explanatory diagram of the key file processing procedure when adding data in FIG. 1. FIG. 5 is an explanatory diagram of the data search method as the second embodiment of the present invention. A configuration diagram of the link information in the data in Fig. 5, Fig. 7 is an explanatory diagram of the processing procedure of the link information after searching in Fig. 5, and Fig. 8 is an illustration of the processing procedure of the link information at the time of addition in Fig. 5. Explanatory diagram: FIG. 9 is an explanatory diagram of the structure of an ISAM file. 01: ISAM file, 02: Key file, 03:
First key file, 1-2: Index block, ■
-3=data block, 1-4 records, 1-5: key position, 1-6: key length, 1-7: data, K: key,
DT, DTI: Searched data, 02H: First part, K
B: Key block, 2-1=Highest priority key block Nα, 2-2=Key length, 2-3: Number of key blocks, 2
-5: Next priority key block Nα, 2-6: Previous priority key block Nα, next priority key at 6-, 6-2:
Priority first Figure 1, Ω2: Key 7 Air O Figure 2

Claims (1)

[Claims] 1) A key that can uniquely identify this searched data is added to the searched data written in random order, and a record as data to which this key is added is defined by the value of the key. In an indexed sequential file system in which the searched data is arranged in ascending order and the searched data can be searched at high speed, a file is provided that stores weights for keys in addition to the existing indexed sequential file. , an indexed sequential organization file characterized in that the searched data can be searched according to this weighting information, so that the searched data can be searched at high speed based on conditions other than the key. Management method. 2) Add a key that can uniquely identify this searched data to the searched data written in random order, and arrange the records as data to which this key is added so that the values of the key are in ascending order. In the indexed sequential file system that allows the searched data to be searched at high speed, link information is added to the searched data to identify the destination of the search time of the data, and the searched data is searched according to this link information. A method for managing indexed sequential files, characterized in that by making system search data searchable, the same searched data can be frequently searched at high speed based on conditions other than the key.