JPH0254370A - Index loading system - Google Patents

Abstract

PURPOSE:To shorten data retrieving time without pressing a main memory device by loading partly a non-resident index into the main memory device. CONSTITUTION:An initialization means 1 starts when the data base service is started. Thus an index loading means 5 starts to read a higher rank index out of an auxiliary memory 6 as a resident index to store the index in a main memory device 10. Then a lower rank index is retrieved after reception of a retrieving request of a data base. Then the means 5 starts to reads a necessary index out of the memory 6 and then stores a lower rank index and the lowest rank index into a non-resident index control means 4. In this case, the lower rank index stored in the device 10 and used to the preceding process is returned. Thus only the higher rank indexes used frequently and limited lower rank indexes are stored in the device 10. As a result, the data retrieving time is shortened.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a database search method.

In particular, it relates to a method for quickly loading indexes when searching for data.

〔overview〕

In addition to the conventional index loading method, the present invention uses an index loading method in which the upper index is loaded into the main memory device at the start of a service, and the lower index is loaded from the auxiliary storage device to the main memory device for each search request. By loading a part of the non-resident index into the main memory device as a resident index when setting initial conditions, data search time is shortened without putting pressure on the main memory device.

[Conventional technology]

In a database, data indexes form a hierarchical structure, and the more data that is registered in the database, the deeper the hierarchical level becomes.

Conventionally, in this type of index loading method, among the hierarchically structured indexes, the upper index is loaded from the auxiliary storage to the main memory at the start of the service, and the lower index is loaded from the auxiliary storage for each search request. loading from the device into the main memory device.

[Problem that the invention seeks to solve]

The conventional index loading method described above loads the lower index from the auxiliary storage to the main memory each time data is searched. This results in unnecessary access to auxiliary storage when attempting to load the data, resulting in slower data retrieval.

Furthermore, since the larger the database, the larger the number of indexes, there is a problem in that loading all the indexes into the main memory device will overwhelm the main memory device.

The present invention is intended to solve these problems, and it is an object of the present invention to provide a method that can shorten data retrieval time without burdening the main memory device.

[Means for solving problems]

The present invention includes an auxiliary storage device and a main memory device, loads an upper index of a hierarchically structured index from the auxiliary storage device to the main memory device, and loads a lower index from the auxiliary storage device to the main memory device for each search request. In an index loading method including means for loading into a memory device, an initial setting means sets initial conditions at the time of starting a database service, and a resident index control means stores an upper index in the main memory device under control of the initial setting means. and an index search means for searching the resident index according to search conditions when a data search request is received from a user.
The present invention is characterized by comprising non-resident index control means for adding and storing a lower index required by the control of the index search means in the main memory device.

[Effect]

When the database service is started, the initial setting means is activated, and the index loading means is activated to read the upper index as a resident index from the auxiliary storage device and store it in the main memory device. At this time, the non-resident index is placed in an unloaded state.

When a database search request is received, the index search means is started, and if it is found that there is no required index in the resident index, it searches the lower indexes and starts the index loading means to assist the necessary index. The index is read from the storage means, further lower indexes are searched, and the index loading means is activated again to cause the retrieved lower and lowest indexes to be stored in the non-resident index control means. At this time,
Returns the lower index used by the previous process stored in main memory.

The same operation is repeated when a new search request is received. As a result, only the frequently used upper index and a limited number of lower indexes that are needed are stored in the main memory, so that data retrieval time can be shortened without burdening the main memory device.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

The embodiment of the present invention includes an initial setting means 1 for loading the upper index at the time of starting a database service, a resident index control means 2 for storing the upper index loaded by the initial setting means 1 in the main memory device 10, and a user an index search means 3 that searches for a lower index from the upper index stored in the resident index control means 2 according to search conditions when a data search request is received from the index search means 3; and a lower index loaded by the index search means 3; The non-resident index control means 4 stores the index in the main memory device 10, and the index loading means 5 loads the index from the auxiliary storage device 6 according to instructions from the initial setting means 1 and the index search means 3.

If the non-resident index control means 4 is in an unloaded state or the lower index is different from the index stored in the non-resident index control means 4, the index search means 3 uses the index loading means 5 to search for the corresponding index. The lower index to be stored is loaded and stored in the non-resident index control means 4, the lowest index of the corresponding index is returned, and if the lower index is the same as the index stored in the non-resident index control means 4, the non-resident index control is performed. It includes means for returning the lowest index of the lower indexes stored in the child actor 4.

Next, the operation of the embodiment of the present invention having one structure as described above will be explained based on a specific example. FIG. 2 is a diagram showing the hierarchical structure of indexes in the embodiment of the present invention. In this embodiment, it is assumed that the index has a maximum of four levels of hierarchy, and the upper two levels are resident indexes.

First, when the database service is started, the initial setting means 1 is activated. The initial setting means 1 starts the index loading means 5 and loads the upper index 11.12.
．． 13 from the auxiliary storage device 6, activates the resident index control means 2, and stores it in the main memory device 10.

Also, the non-resident index control means 4 is brought into an unloaded state.

Next, when a database search request (assumed to be a search request for data d1) is received, the index search means 3 is activated and traces the indexes 11 and 12 stored in the resident index control means 2 to find the lower index. I know that he is 14. Here, since the non-resident index control means 4 has not been loaded, the index search means 3 activates the index loading means 5 to read the index 14 from the auxiliary storage device 6, and confirms that a lower index 17 exists. Knowing this, the index loading means 5 is activated again to read the index 17 from the auxiliary storage device 6. At this point, index search means 3 knows that index 17 is the lowest index, instructs non-resident index control means 4 to store index 14.17, and returns index 17 to the search request source. After this, the non-resident index control means 4 stores the index i4.17.

Next, make a new search request (this is a search request for data d3).
When the index search means 3 is accepted, the index search means 3 is activated.
The index search means 3 traces indexes 11 and 12 in the same way as in the previous process, and learns that the lower index is i4. Here, since the index stored in the non-resident index control means 4 is 14.17, the index search means 3 traces the index 14, j7 without accessing the auxiliary storage device 6, and finds that the lowest index is 17. Knowing this, the index 17 is returned to the search request source.

Next, make a new search request (a search request for data d4).
Upon receiving the request, the index search means 3 traces the search to the index 14 in the same manner as the second search request. At this point, knowing that the lower index is 18, the index retrieval means 3 activates the index loading means 5 to read the index 18.
is the lowest index, instructs the non-resident index control means 4 to store indexes i4 and i8, and returns index 18 to the search request source. After this, the non-resident index control means 4 stores the index i4.18.

〔Effect of the invention〕

As explained above, according to the present invention, in addition to the conventional index loading method, by loading a part of the non-resident index into the main memory device, data inspection time can be reduced without putting pressure on the main memory device. It has the effect of being able to shorten the time.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of the present invention. FIG. 2 is a diagram showing the hierarchical structure of the index according to the embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Initial setting means, 2... Resident index control means, 3... Index search means, 4... Non-resident index control means, 5... Index loading means, 6... Auxiliary storage device , 10... Main memory device, i-19... Index, d1-d7... Data.

Claims (1)

[Scope of Claims] 1. An auxiliary storage device and a main memory device are provided, and an upper index of a hierarchically structured index is loaded from the auxiliary storage device to the main memory device, and a lower index is loaded into the auxiliary storage device for each search request. In an index loading method including means for loading an index from a device to the main memory device, an initial setting means sets initial conditions at the time of starting a database service, and an upper index is stored in the main memory device under the control of the initial setting means. a resident index control means; an index search means for searching the resident index according to search conditions when a data search request is received from a user; and a lower index required by the control of the index search means is stored in the main memory. An index loading method characterized by comprising a non-resident index control means that is added to and stored in a device.