JPH0797346B2 - File access device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a file access capable of accessing a data file consisting of a collection of records on an auxiliary storage device such as a magnetic disk device by an index. Regarding the device.

[Conventional technology]

Conventionally, in this type of file access device, when a data file is updated, there are a method of updating all indexes for an index that is not used at that time and a method of not updating an index that is rarely used. There is. In the latter case,
When access by the index becomes necessary, if the data file is updated after the index is no longer updated, the index is reorganized.

[Problems to be Solved by the Invention]

In the above-mentioned conventional file access device, when the access by the index is necessary, the index is reorganized if the data file is updated after the index is not updated. Even though the data file is updated after the index is no longer updated, the index reorganization takes place, even though the index does not need to be reorganized if its index fields have not changed, which is a time consuming process. There is a drawback that it ends up.

[Means for Solving the Problems]

A file access device of the present invention is a file access device for accessing a data file consisting of a collection of records on an auxiliary storage device such as a magnetic disk device by an index, and accessing a data file and an index file. A file access mechanism, an index update mechanism that updates the index when the data file is updated, and an index update mechanism that updates the index when the data file is updated. When the file is updated, it is checked whether the index field is updated for the index file that is specified not to be updated. When the index field is updated, the index field is updated for the index file thereafter. An index update management mechanism that disables the checking of whether or not If the index update management mechanism indicates that the index field is updated for the index file that is specified not to be updated when updating the data file when the index access by the reference file becomes necessary. , And an index reorganization mechanism for reorganizing the index of the index file.

[Action]

When it becomes necessary to access the index by the index file,
Since the index reorganization is performed only for the index file whose index field has been updated by updating the data file after the index file is no longer updated, the processing time is short.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram of an embodiment of the file access device of the present invention, and FIG. 2 is a flow chart of processing of the index update management mechanism 2.

The file access mechanism 1 is a mechanism for accessing the data file 10 and the index files 11, 12, and 13. The index update management mechanism 2 is a mechanism for managing whether the index field is updated when the data file 10 is updated. Update mechanism 3
Is a mechanism for updating the index files 11, 12, 13 when the data file 10 is updated, and the index reorganization mechanism 4 uses the data in the data file 10 for index file 1 when accessing the index.
It is a mechanism to reorganize 1,12,13.

Here, the index file 11 is designated as an index to be updated when the data file 10 is updated, and the index files 12, 13
Is specified as an index that is not updated when the data file 10 is updated. In addition, the index file
It is assumed that the data files 10 and 12 and 13 are not updated at some point after the index is reorganized for index access. That is, at that point the index files 11, 12, 13
Are all consistent with data file 10.

After the above point, when the data file 10 is updated,
Since the index file 11 is an index that is updated when the data file 10 is updated, the index update mechanism 3 performs the index update process. Since the index files 12 and 13 are indexes that are not updated when the data file 10 is updated, the index update management mechanism 2 performs the processing shown in the flowchart of FIG.

Index files 12 and 13 are datafile 10 because datafile 10 was not updated after the index was reorganized.
It is necessary to check whether or not the index field has been updated at the time of updating.

Further, assuming that the update of the data file 10 updates the index field of the index file 12 and the index field of the index file 13 is not updated, it is known that the index file 12 has already been updated. When the data file 10 is updated thereafter, the index file 12 is not checked whether the index field has been updated. A check is made on the index file 13. At this time, if index access by the index files 12 and 13 is required, it is known that the index field of the index file 12 has been updated as described above. Reorganization is performed. As a result of the above check, the index file 13 is used as it is without reorganization of the index unless the index field is updated.

On the other hand, in the conventional method, the index file
Since the data file 10 is updated after the index files 12 and 13 are not updated in both 12 and 13, when the index access by the index files 12 and 13 becomes necessary,
Index reorganization is performed on both the index files 12 and 13.

〔The invention's effect〕

As described above, according to the present invention, at the time of accessing an index, even if the data file is updated after the index is no longer updated, the index is not reorganized if the index field is not changed. There is an effect that the processing time is short.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an embodiment of the file access device of the present invention, and FIG. 2 is a flow chart of processing of the index update management mechanism 2. 1 ... File access mechanism, 2 ... Index update management mechanism, 3 ... Index update mechanism, 4 ... Index reorganization mechanism, 10 ... Data file, 11-13 ... Index file.

Claims (1)

[Claims] 1. A data file comprising a collection of records on an auxiliary storage device such as a magnetic disk device,
A file access device that accesses by index, a file access mechanism that accesses the data file and the index file, and a specification that when the data file is updated, the index is updated when the data file is updated. An index update mechanism that updates the index of the index file, and when the data file is updated, checks whether the index field has been updated for the index file that is specified not to be updated when the data file is updated. When an index field is updated, an index update management mechanism that does not check whether the index field has been updated for the index file thereafter, and an index access by the index file occurs,
If the index update management mechanism indicates that the index field is updated for the index file that is specified not to update the index when updating the data file,
A file access device having an index reorganization mechanism for reorganizing an index for the index file.