JPS6148034A - Dynamic size changing system of hashing table - Google Patents

Abstract

PURPOSE:To obtain a retrieval method by which even if the number of a symbol is changed, a retrieval efficiency is not lowered, and an usually and unnecessarily large hashing table is not required by changing dynamically the size of a hashing table in accordance with the number of a symbol. CONSTITUTION:In a table retrieval, the name of a command symbol is given to a hashing function 18, an entry in a hashing table 15 is obtained and from this entry, a symbol name is searched to obtain a suitable value. If the collision of the symbol name is generated and the hashing values overlaps, the processing is doned by using an overflow table 16. When an operator of TSS terminal enters LOGON command and begins TSS session, an initializing routine 6 begins to operate, reads a command symbol from a data set 8 for profiling a command and extends it to a symbol table.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a symbol table search using a hashing method, and in particular a dynamic method suitable for a symbol table search method in which the number of symbols dynamically changes significantly. [Background of the Invention] In the conventional symbol table search method using the hashing method, the size of the hashing table and the hashing function were fixed, so the number of symbols was Sing Cheeple's En) 'J It had the disadvantage that the search efficiency decreased as the attack approached.

To prevent this, it is necessary to create an unnecessarily large hashing table to prevent the hashing table from becoming full, resulting in a decrease in memory usage efficiency.

[Purpose of the invention]

An object of the present invention is to change the size of a hashing table depending on the number of symbols, so that even if the number of symbols is changed, the search efficiency does not decrease, and the hashing table is always unnecessarily large. The objective is to provide a search method that does not require any additional information.

[Summary of the invention]

The present invention provides a table for registering symbol names and their corresponding values on a computer system.

In a symbol table search system consisting of a search mechanism based on the sing method, the size of the hashing cheeple and the hashing function used for symbol Jk hashing searches are changed so that the search efficiency does not decrease even when the number of registered symbols changes. R to do? :t.

[Examples of actual inventions]

An embodiment of the present invention will be described below with reference to the drawings. -1 FIG. 1 shows the entire outline of a letter command profile system built on a time sharing system (TSS) as an embodiment of the present invention. The command profile system is a system that provides a personal data storage location for each user who operates a terminal to store various options and stored values in order to create his or her own TSS environment. In this system, with the notation name ``command symbol name 1'', it is possible to search for the value ``command symbol 1 straight 2'' corresponding to that symbol. FIG. 1 shows the OFF message in the terminal monitor program 5 when LQGQN is sent from the TSS terminal 6 to the TSS on the computer system 4. The processing routine 6 creates a command symbol table 9 on the virtual storage device from the command profile data bit 8, and at LOGOFF, the completion routine 7 writes the contents of the command symbol table 9 to the command profile data bit 8. Indicates to store. T.S.
In S, the unit of terminal operation from LOGON to 1,0GOFF is called 'rss-tr', and during that TSS session, the command processor 11 of s:s S, the user-created program 12, and the command procedure that is a macro command 13 to command symbol macro group 10
It can be accessed through.

FIG. 2 shows details of the command symbol table 9. The command symbol table 9 is the command symbol management table 14.
, a hashing table 15 and its over 70-table 16, and a command symbol name-value table 17. To search this table, pass the command symbol name to the hashing function 1B to find the entry in the hashing table. Find the symbol name from this entry and get the value. If a conflict of symbol names occurs and hashing entries overlap, one over-70-table is used. The overflow table is searched sequentially.

FIG. 3 shows the details of the initialization routine 6 that operates when the TSS terminal operator inputs the LOGON password and starts a TSS session.

This routine executes command profile data sector 8.
Read the command symbol from Command 1;
Exhibition IJi□J to Le. The first record of length 1 in command profile data sector 8 contains the number of symbols and nonta 1.
9 is in Rakuno, and this counter 11 white is 1 at the beginning of 1υ.
1. The size of the hatching cheeple and the hashing function are determined by the algorithm shown in FIGS. 41 and 5.

Thereafter, the command symbols stored after the second record of the command profile 11 data set are registered one by one in the table.

FIG. 4 does not show the algorithm for determining the size of the hashing table. This algorithm assumes a margin so that the search efficiency of Hashing Cheeple does not decrease.If the value of the command symbol counter 19 is from 0 to 50, there will be 100 entries, if the value is from 51 to 100, it will be 200 entries, and if the value is from 51 to 100, it will be counted. has created twice as many entries. In addition to determining the size of the hashing table, the algorithm shown in Figure 5 is used to distribute the hashing functions 18 to the hashing table as evenly as possible. ;i, shows the algorithm of hacking single A politics. In this function, the symbol name is encoded by the number of entries in the hashing table, and the value extracted every other digit of 16 is t;1. Therefore, even if the size of the hashing table changes, the hashing function uses the entire hashing table for I'tT as uniformly as possible.

FIG. 6 shows a command symbol macro group 10 for referencing, registering, changing, and deleting command symbols. Always use this macro to access command symbols. This macro;1B
The command symbol counter 19 is incremented by 1 when registering a command symbol;Q;A, and decremented by 1 when deleting a humanto symbol. Therefore, the command symbol counter 19 always maintains the current command number -3.

Figure 7 shows terminal i-☆ when the author executes the LOGOFF command to terminate the TSS session 1・I'ii+
t's: End J' Routine 7 fraud≦201. This routine writes 11 entries into the command symbol counter 19 into the command profile 1[1 data center, and then writes the command symbol name and fil'f. Command profile data set G11t created with this (-),
Next time, when 1,0 GONL/ is obtained, it will be read and set to 1.

If a large number of command symbols are registered in - times of TSS sessions, the hashing table becomes large in the next TSS session, and the search efficiency does not deteriorate. In addition, by inputting the a M D P ROF command from the ``li'' tree, the ``71 twinning table size?'' is generated during the rSs session. It can change history.

As is clear from the above explanation, according to this embodiment, when jl( of the command description increases, a larger hashing table 2 is created, and when it decreases, a smaller hashing table 2 is created. This has the effect of making it possible to reduce the amount of memory required without reducing efficiency.

〔Effect of the invention〕

According to the present invention, in a search system using a hashing table, the size of the hashing table can be dynamically changed, so that the number of registered symbols increases or decreases by 50% or less between one size change and the next change. If there is, on average, only two search comparisons will be required and the storage space will be twice as large as the number of registered symbols)
There is an effect that IJM can be used.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the overall picture of the command profile system, Figure 2 is a block diagram showing details of command symbols, Figure 3 is a block diagram showing details of command symbol table initialization processing, and Figure 4 is a hashing diagram. Fig. 5 is an explanatory diagram showing the table creation algorithm, Fig. 5 is an explanatory diagram showing the hashing function, Fig. 6 is a block diagram showing access processing using a command symbol macro group, and Fig. 'B7 is an explanatory diagram showing details of command symbol table storage processing. It is. 1...Command symbol 2...Command symbol value 3...TSS terminal 4...Electronic meter W (Iso system 5...ff1i, end monitor program 6...Initialization routine 7... Storage routine 9...Command symbol table 10...Command symbol macro group 11...Command processor 12...User program 16...Command procedure 14...Command symbol management table 15...Hashing cheaple 18... Hashing function 19... Symbol number counter

Claims (1)

[Claims] 1. In a symbol table search system on a computer system that consists of a table in which symbol names and their corresponding values are registered and a search mechanism using a hashing method, the size of the hashing table and the hashing function used for the search are changed using a symbol number counter. A method for dynamically changing the size of a hashing table, which is characterized in that search efficiency does not decrease even if the number of symbols registered in the hashing table changes.