U.S. patent application number 11/189702 was filed with the patent office on 2005-11-24 for database processing method, apparatus for implementing same, and medium containing processing program therefor.
Invention is credited to Iwata, Morihiro, Kobayashi, Susumu, Nakano, Yukio, Tsuchida, Masashi.
Application Number | 20050262078 11/189702 |
Document ID | / |
Family ID | 18350135 |
Filed Date | 2005-11-24 |
United States Patent
Application |
20050262078 |
Kind Code |
A1 |
Nakano, Yukio ; et
al. |
November 24, 2005 |
Database processing method, apparatus for implementing same, and
medium containing processing program therefor
Abstract
A database processing method for defining and operating data of
file reference type which references a file. A column data insert
request for specifying position information indicative of a storage
location of a file and watch information for watching the file is
received from a database client. A request for watching a file
indicated by the position information is issued in accordance with
the watch information. The position information and the watch
information are stored in a database. The foregoing operations
permit data in an external file placed outside a database to be
treated as data equivalent to ordinary column data stored in the
database to improve the integrity of the database.
Inventors: |
Nakano, Yukio; (Oyama-shi,
JP) ; Iwata, Morihiro; (Tama-shi, JP) ;
Kobayashi, Susumu; (Kawasaki-shi, JP) ; Tsuchida,
Masashi; (Machida-shi, JP) |
Correspondence
Address: |
MATTINGLY, STANGER, MALUR & BRUNDIDGE, P.C.
1800 DIAGONAL ROAD
SUITE 370
ALEXANDRIA
VA
22314
US
|
Family ID: |
18350135 |
Appl. No.: |
11/189702 |
Filed: |
July 27, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11189702 |
Jul 27, 2005 |
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10725454 |
Dec 3, 2003 |
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6938043 |
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10725454 |
Dec 3, 2003 |
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10242441 |
Sep 13, 2002 |
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6728710 |
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10242441 |
Sep 13, 2002 |
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09452172 |
Dec 1, 1999 |
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6505199 |
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Current U.S.
Class: |
1/1 ;
707/999.008; 707/E17.005 |
Current CPC
Class: |
Y10S 707/99938 20130101;
G06F 16/2365 20190101; Y10S 707/99945 20130101; G06F 16/217
20190101 |
Class at
Publication: |
707/008 |
International
Class: |
G06F 017/30 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 1, 1998 |
JP |
10-341964 |
Claims
What is claimed is:
1. A database processing method for processing a database system
which stores link information for linking data with a database, the
data being stored on external of the database, said database
processing method comprising the steps of: designating, by a user,
a timing at which information fetched in the database and
concerning link destination data is synchronized with the link
destination data; and executing synchronization between the
information and the link destination data at the timing designated
by the user.
2. The database processing method according to claim 1, wherein the
step of executing synchronization comprises the steps of: checking
whether the link destination data has been updated or not; and if
the link destination data has been updated, altering the
information in the database concerning the link destination data in
accordance with an update of the link destination data.
3. A database processing method for processing a database system
which stores link information for linking data with a database, the
data being stored external of the database, the method comprising
the steps of: designating, by a user, a timing of making a
correspondence relationship between information fetched in the
database concerning link destination data and the link destination
data; and executing making the correspondence relationship between
the information and the link destination data at the timing
designated by the user.
4. A database processing method for processing a database system
which stores link information for linking data with a database, the
data being stored external of the database, the method comprising
the steps of: designating, by a user, a timing of making a
correspondence relationship between information fetched in the
database concerning link destination data and the link destination
data; and executing, by a file server which processes the database,
making the correspondence relationship between the information and
the link destination data at the timing designated by the user.
Description
[0001] The present application is a continuation of application
Ser. No. 10/725, 454, filed Dec. 3, 2003; which is a continuation
of application Ser. No. 10/242,441, filed Sep. 13, 2002; which is a
continuation of application Ser. No. 09/452,172, filed Dec. 1,
1999, now U.S. Pat. No. 6,505,199, the contents of which are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates generally to a database
processing system which references files, and more particularly to
a technology which is effectively applied to a database processing
system that executes definitions and operations for data of file
reference type capable of referencing a file so as to improve the
integrity of a database (DB).
[0003] A database management system (hereinafter abbreviated as the
"DBMS"), particularly a relational DBMS, processes queries which
are expressed in a non-procedural language. The SQL (Structured
Query Language) has been employed as this database language. At
present, the standardization is under progress for next generation
SQL (under ISO, ANSI) in the database language SQL. The reference
type is one of main functions implemented in the next generation
SQL. The reference type stores a pointer in a particular row in a
separate table within a DB, rather than storing a value in a
column. In this way, information in a referenced row can be
provided as shared data.
[0004] In recent years, there has been an increasing need for
employing a DBMS to manage multimedia data including texts,
graphics, pictures, audio, moving image data and so on which may be
accessed through WWW (World Wide Web) or the like. However, these
data are generally produced and modified by their individual
applications dedicated thereto, so that once data is stored within
a DBMS, the data must be retrieved from and stored again in the
DBMS when a dedicated application has to handle data produced
thereby. To eliminate this inconvenience, an external file function
has been devised for equally handling data stored in a file placed
external to a DBMS, as if the data were stored in the DBMS, by
indicating this external file. This external file function is
supported as BFILE type in Oracle8 which is an RDBMS available from
ORACLE Corporation. Also, IBM has published a similar external file
function called "DataLinks" for its DB2 Universal Database (see
Search Report, DataLinks: MANAGING EXTERNAL DADA WITH DB2 UNIVERSAL
DATABASE, by InfoIT, Inc., pp 10-11, August 1997).
[0005] As part of core capabilities, conventional DBMS's maintain
the integrity, so that rows of a DB are established together with
the existence of all columns, and only values in a certain column
will never be missing. When a column, for which an index is
defined, is updated, the index must be modified to have the most
recent information. Thus, if a. conventional DBMS is simply
provided with the ability of handling external files, operations
such as update, delete and so on will be performed to such external
files out of the management of the DBMS. Since the external files
are not managed by the DBMS, the operations performed thereon will
arise a problem in that the DBMS suffers from difficulties in
maintaining the integrity such as that normally maintained within
columns of the DBMS.
[0006] While a method of indicating an external tile 10 out of the
management of a DBMS has been contemplated in the aforementioned
background art techniques, the BFILE type is dedicated to reading,
so that it is not recovered when a fault occurs. Moreover, the
BFILE type is not a function created in consideration of an update
performed outside a DBMS. DataLinks, in turn, employs a method of
controlling external files such that they are not rewritten by
external applications or the like which do not have an access right
to a DB from which the external files may be accessed, in order to
restrict accesses to external files. DataLinks, however, does not
consider actions to take in the DBMS itself when an associated
external file is updated.
SUMMARY OF THE INVENTION
[0007] It is therefore an object of the present invention to
provide a technology which is capable of improving the integrity of
a database by treating data in external files placed outside the
database as data equivalent to ordinary column data stored in the
database.
[0008] Specifically, the present invention provides a database
processing system for defining and operating data of external file
reference type capable of referencing an external file, wherein
external files registered in a database are watched to check
whether any file is updated or deleted, and column data within the
database is updated corresponding to any processing on the external
files.
[0009] In the database processing system according to the present
invention, when column data is inserted, a watch request is issued
in accordance with watch information in the column data for
watching an external file indicated by position information in the
column data. Then, the position information and the watch
information in the column data are stored in the database.
[0010] When table select processing is performed, a processing type
is examined in a table select request. When the processing type
indicates a select of column data, the database processing system
sends to a database client column data which meets a select
condition. When the processing type indicates a select of the
contents of an external file, the database processing system
acquires the contents of an external file indicated by position
information in column data, which meets the select condition, and
transmits the contents to the database client.
[0011] Also, when table update processing is performed, a
processing type in a table update request is examined. When the
processing type indicates an update of column data, the database
processing system notifies the termination of a watch on an
external file indicated by position information in column data to
be updated in accordance with watch information in the column data
to be updated. After updating the column data to be updated with
position information and watch information in the table update
request, the database processing system issues a request for
watching an external file indicated by the position information in
the table update request in accordance with the watch information
in the table update request.
[0012] When the processing type in the table update request
indicates an update of contents of an external file in the table
update processing, the database processing system updates the
contents of an external file indicated by the position information
in the column data to be updated with the contents of an external
file indicted by the position information in the table update
request.
[0013] When table delete processing is performed, the database
processing system notifies the termination of a watch on an
external file in accordance with watch information in column data
to be deleted. When the processing type indicates a delete of the
contents of an external file, the database processing system
deletes the external file, and then the column data to be
deleted.
[0014] When a request for watching an external file is issued in a
manner mentioned above, the database processing system registers a
watched file list with information on the external file, and
initiates watching the external file. If the external file is
updated or deleted, the database processing system sends to a watch
requester an update notice indicating that the external file has
been updated or deleted. When a watch termination notice is
transmitted to terminate the watch on the external file, the
database processing system deletes information on the external file
associated with the watch termination notice from the watched file
list.
[0015] When an update notice for the external file is sent, the
contents of the update notice are examined. When the update notice
indicates an update of an external file, the database processing
system executes maintenance processing on an index which is
registered in column data that indicates the updated external file.
On the other hand, when the update notice indicates a delete of an
external file, the database processing system deletes a row
corresponding to column data that indicates the deleted external
file, and executes maintenance processing on an index which is
registered in a table.
[0016] As described above, in the present invention, the external
file reference type is added to data types available in a DBMS, and
position information and watch information are entered as data, so
that the contents of an external file can be referenced as data
linked by specified position information. The integrity of the DBMS
can be maintained by watching whether any external file has been
updated or deleted at a frequency specified in the watch
information, and detecting any external file updated or deleted
from another application or the like. It is therefore possible to
treat external files as data equivalent to ordinary column data
stored in a database without the need for storing the contents of
external file in the DBMS.
[0017] As is appreciated from the foregoing, the database
processing system according to the present invention detects an
update or a delete performed on any external file indicated by
position information in column data within a database, and updates
column data within the database corresponding to processing
performed on the external file, so that data within external files
placed outside the database can be treated as data equivalent to
ordinary column data stored in the database itself without damaging
the integrity of the database.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a block diagram generally illustrating the
configuration of a database processing system according to one
embodiment of the present invention;
[0019] FIG. 2 is a block diagram generally illustrating the
configuration of a DB server 100 and a file server 140 in the
embodiment of FIG. 1;
[0020] FIG. 3 illustrates an outline of the processing performed by
a DBMS 103 and a DBMS update watch processing unit 145 in the
embodiment of FIG. 1;
[0021] FIG. 4 illustrates an outline of table definition processing
in the embodiment of FIG. 1;
[0022] FIG. 5 is a flow chart illustrating a processing procedure
for the table definition processing in the embodiment of FIG.
4;
[0023] FIG. 6 illustrates an outline of data insert processing in
the embodiment of FIG. 1;
[0024] FIG. 7 is a flow chart illustrating a processing procedure
for the data insert processing in the embodiment of FIG. 6;
[0025] FIG. 8 illustrates an outline of external file reference
type data insert processing in the embodiment of FIG. 1;
[0026] FIG. 9 is a flow chart illustrating a processing procedure
for the external file reference type data insert processing in the
embodiment of FIG. 8;
[0027] FIG. 10 is a flow chart illustrating a processing procedure
for watch initiation processing in the embodiment of FIG. 1;
[0028] FIG. 11 is a flow chart illustrating a processing procedure
for check initiation processing in the embodiment of FIG. 1;
[0029] FIG. 12 illustrates an outline of data select processing in
the embodiment of FIG. 1;
[0030] FIG. 13 is a flow chart illustrating a processing procedure
for the data select processing in the embodiment of FIG. 12;
[0031] FIG. 14 illustrates an outline of column data update
processing in the embodiment of FIG. 1;
[0032] FIG. 15 is a flow chart illustrating a processing procedure
for the column data update processing in the embodiment of FIG.
14;
[0033] FIG. 16 illustrates an outline of how watch processing is
terminated during external file change processing in the embodiment
of FIG. 1;
[0034] FIG. 17 illustrates an outline of how the watch processing
is initiated during the external file change processing in the
embodiment of FIG. 1;
[0035] FIG. 18 is a flow chart illustrating a processing procedure
for external data reference type column data update processing in
the embodiment of FIG. 1;
[0036] FIG. 19 is a flow chart illustrating a processing procedure
for watch termination processing in the embodiment of FIG. 1;
[0037] FIG. 20 is a flow chart illustrating a processing procedure
for check termination processing in the embodiment of FIG. 1;
[0038] FIG. 21 illustrates an outline of data delete processing in
the embodiment of FIG. 1;
[0039] FIG. 22 is a flow chart illustrating a processing procedure
for the data delete processing in the embodiment of FIG. 21;
[0040] FIG. 23 is a flow chart illustrating a processing procedure
for the data delete processing in the embodiment of FIG. 21;
[0041] FIG. 24 illustrates an outline of the processing performed
by an I/O watch processing unit 243 in the embodiment of FIG.
3;
[0042] FIG. 25 is a flow chart illustrating a processing procedure
for the I/O watch processing in the embodiment of FIG. 24;
[0043] FIG. 26 is a flow chart illustrating a processing procedure
for update notice acceptance processing in the embodiment of FIG.
24;
[0044] FIG. 27 illustrates an outline of update check processing in
the embodiment of FIG. 1; and
[0045] FIG. 28 is a flow chart illustrating a processing procedure
for the update check processing in the embodiment of FIG. 27.
DESCRIPTION OF THE EMBODIMENTS
[0046] The present invention will hereinafter be described in
connection with a database processing system according to one
embodiment thereof which executes definitions and operations on
data of external file reference type data, capable of referencing
external files, without damaging the integrity of a DB server.
[0047] FIG. 1 illustrates in block diagram form the general
configuration of a database processing system according to one
embodiment of the present invention. A DBMS 103 is operating in a
DB server 100; a DB access application 131 in a DB client 130; a
DBMS update watch processing unit 145, which forms part of
functions provided by the database processing system according to
this embodiment, in a file server 140; and WWW servers 141, 157 and
data access applications 146, 147, 151, 156 in file servers 140,
150, respectively. These information processing devices are
connected to a network 160 so that they can communicate with each
other.
[0048] The DB access application 131 issues a query request to the
DBMS 103 on the DB server 100 through the network 160. Upon receipt
of the query request, the DBMS 103 accesses DB data 111 and a
journal file 121 respectively stored in disk drives 110, 120
connected to the DB server 100 to execute processing corresponding
to the query request.
[0049] The data access applications 146, 147, 151, 156 are programs
for generating and processing dedicated data such as texts, images
and so on. Text data and image data created by these applications
are stored in disk drives 142, 152 connected to the file servers
140, 150, respectively. Text data 143, 153 and image data 144, 154
stored in the disk drives 142, 152 are open to other information
processing devices through the WWW servers 141, 157, so that
corresponding data may be transferred by specifying any of URLs
(Uniform Resource Locator) previously assigned to the WWW servers
141 and 157 to request an access to the specified WWW server.
[0050] The DBMS update watch processing unit 145 is run in
association with the DBMS 103 to watch input and output operations
involved in applications such as the data access applications 146,
147 executed on the file server 140; to create a watched file list
148 as a list of files subjected to a watch requested by the DBMS
103; and to watch update processing on the files registered on the
watched file list 148.
[0051] FIG. 2 illustrates in block diagram form the general
configuration of the DB server 100 and the file server 140 of this
embodiment. As can be seen in FIG. 2, the DB server 100 of this
embodiment comprises a processing request acceptance processing
unit 200; a table definition processing unit 201; an insert
processing unit 202; a select processing unit 203; an update
processing unit 204; a delete processing unit 205; an update notice
acceptance processing unit 206; a check initiation processing unit
207; a check termination processing unit 208; an update check
processing unit 209; a watch request processing unit 211; a watch
termination notification unit 212; and an index maintenance
processing unit 213.
[0052] The processing request acceptance processing unit 200 is a
processing unit which accepts from the DB client 130, a column data
insert request; a table select request; a table update request; and
a table delete request each for specifying position information
indicative of a storage location of an external file; watch
information for watching the external file; and a processing type
which indicates which of column data and the contents of the
external file are to be processed.
[0053] The table definition processing unit 201 is a processing
unit which defines a table by setting a table name and the number
of columns in table information within DB information; sets the
table name, column names and column data types in column
information within the DB information; and sets information
indicative of an external file reference type in column information
of an associated column if this column is specified, in the column
data type, as an external file reference type capable of
referencing an external file.
[0054] The insert processing unit 202 is a processing unit which
stores column data including the position information and the watch
information in a database. The select processing unit 203 is a
processing unit for transmitting to the DB client 130 column data
to be selected or the contents of an external file indicated by its
position information in accordance with the contents of the
processing type.
[0055] The update processing unit 204 is a processing unit which
updates column data to be updated or the contents of an external
file indicated by its position information in accordance with the
contents of the processing type with column data in a table update
request or the contents of an external file indicated by its
position information.
[0056] The delete processing unit 205 is a processing unit which
deletes an external file indicated by position information in
column data to be deleted, and also deletes the column data to be
deleted, when the processing type indicates a delete of the
contents of an external file. The update notice acceptance
processing unit 206 is a processing unit which receives an update
notice for an external file referenced by external file reference
type column data. In addition, when the update notice indicates a
delete of the external file, the update notice acceptance
processing unit 206 deletes a row corresponding to the column data
indicating the deleted external file.
[0057] The check initiation processing unit 207 is a watch
initiation processing unit which receives a watch request for
requesting a watch on an external file, and registers a checked
file list with information on the external file subjected to the
requested watch. The check termination processing unit 208 is a
watch termination processing unit which receives a watch
termination notice for terminating the watch on an external file,
and deletes information on the external file, associated with the
received watch termination notice, from the checked file list.
[0058] The update check processing unit 209 is a watch processing
unit which watches an external file registered on the checked file
list, and sends to a watch requester an update notice indicative of
update or delete of the external file, when the external file is
updated or deleted.
[0059] The watch request processing unit 211 is a processing unit
which requests a watch initiation processing unit 241 of the DBMS
update watch processing unit 145 or the check initiation processing
unit 207 to watch an external file indicated by position
information in accordance with watch information. The watch
termination notification processing unit 212 is a processing unit
which notifies the termination of a watch on an external file
indicated by position information to a watch termination processing
unit 242 of the DBMS update watch processing unit 145 or to the
check termination processing unit 208 in accordance with watch
information. The index maintenance processing unit 213 is a
processing unit which executes maintenance processing on indexes in
accordance with an update or delete of an external file.
[0060] Programs for instructing the DB server 100 to function as
the processing request acceptance processing unit 200, the table
definition processing unit 201, the insert processing unit 202, the
select processing unit 203, the update processing unit 204, the
delete processing unit 205, the update notice acceptance processing
unit 206, the check initiation processing unit 207, the check
termination processing unit 208, the update check processing unit
209, the watch request processing unit 211, the watch termination
notification processing unit 212, and the index maintenance
processing unit 213 are assumed to be recorded on a recording
medium such as a CD-ROM or the like, stored in a magnetic disk or
the like from the CD-ROM, and loaded from the magnetic disk into a
memory for execution. Alternatively, the programs may be recorded
on any medium other than CD-ROM.
[0061] The file server 140 comprises a watch initiation processing
unit 241, a watch termination processing unit 242, and an I/O watch
processing unit 243.
[0062] The watch initiation processing unit 241 is a processing
unit which receives a watch request for requesting a watch on an
external file, and registers the watched file list 148 with
information on the external file associated with the received watch
request. The watch termination processing unit 242 is a processing
unit which receives a watch termination notice for terminating a
watch on an external file, and deletes information on the external
file, associated with the received watch termination notice, from
the watched file list 148.
[0063] The I/O watch processing unit 243 is a processing unit which
watches an external file registered on the watched file list 148 to
send to a watch requester an update notice indicative of update or
delete of the external file, when the external file is updated or
deleted.
[0064] Programs for instructing the file server 140 to function as
the watch initiation processing unit 241, the watch termination
processing unit 242 and the I/O watch processing unit 243 are
assumed to be recorded on a recording medium such as a CD-ROM or
the like, stored in a magnetic disk or the like from the CD-ROM,
and loaded from the magnetic disk into a memory for execution.
Alternatively, the programs may be recorded on any medium other
than CD-ROM.
[0065] The DB server 100 comprises a CPU 313; a memory 314; an I/O
controller 312; and a communication controller 311. Programs
associated with the DBMS 103 stored in the memory 314 are executed
by the CPU 313 to perform processing on the DBMS 103. The I/O
controller 312 reads and writes data from and to the disk drives
110, 120, while the communication controller 311 transmits and
receives data to and from other information processing devices
interconnected through the network 160.
[0066] The DB client 130, implemented in a similar configuration,
has the DB access application 131 stored in a memory for execution.
When the DB access application 131 issues a query request to the
DBMS 103, the query request is transmitted from the DB client 130
to the communication controller 311 of the DB server 100, and then
sent to the DBMS 103. The DBMS 103 executes processing in
accordance with the request. When the processing requires an access
to the DB data 111, the access to the DB data 111 stored in the
disk drive 110 is performed through the I/O controller 312. The
processing result is transferred to the DB client 130 by the
communication controller 311 and then sent to the DB access
application 131, i.e., the requester.
[0067] In the file servers 140, 150, the data access applications
146, 147 stored in a memory, and the WWW servers 141, 157 are being
executed. Also, in the file server 140, a program for instructing
the file server 140 to function as the DBMS update watch processing
unit 145 is stored in a memory 302, and is being executed. When the
DBMS 103 of the DB server 100 requests the file server 140 to watch
an external file, the watch request is transmitted from the
communication controller 311 of the DB server 100 to a
communication controller 303 of the file server 140, and then sent
to the DBMS update watch processing unit 145. The DBMS update watch
processing unit 145 executes processing in accordance with the
request. When an external file is updated or deleted, the DBMS
update watch processing unit 145 transfers an update notice to the
communication controller 303 of the DB server 100 through the
communication controller 311, and then sent to the DBMS 103, i.e.,
the requester.
[0068] FIG. 3 illustrates an outline of the processing performed by
the DBMS 103 and the DBMS update watch processing unit 145 of this
embodiment. Upon receipt of a processing request 210, the DBMS 103
analyzes the request, and performs operations required for the
request in cooperation with the table definition processing unit
201, the insert processing unit 202, the select processing unit
203, the update processing unit 204, and the delete processing unit
205.
[0069] The check initiation processing unit 207, the check
termination processing unit 208 and the update check processing
unit 209 respectively perform processing for initiating,
terminating and conducting a check as to whether data has been
updated in an information processing device not provided with the
DBMS update watch processing unit 145, for example, in the file
server 150 in FIG. 1, when the text data 153 and the image data 154
stored in the disk drive 152 are data used as data of the DBMS
103.
[0070] The watch initiation processing unit 241, the watch
termination processing unit 242 and the I/O watch processing unit
243 of the DBMS update watch processing unit 145 respectively
perform processing for initiating, terminating and conducting a
watch as to whether data has been updated when the text data 143
and the image data 144 stored in the disk drive 142 are data used
as data of the DBMS 103. The watched file list 148 stores a list of
files subjected to the watch.
[0071] When the update check processing unit 209 or the I/O watch
processing unit 243 detects an updated file, the update check
processing unit 209 or the I/O watch processing unit 243 notifies
the update notice acceptance processing unit 206 that the file has
been updated.
[0072] The disk drive 110 stores DB information 222, table data 223
and index data 224 as the DB data 111, where the DB information 222
includes table information 225, column information 226, index
information 227, a checked file list 228 and so on.
[0073] The table information 225 is provided with additional
information when a table is created, and information such as a
table name, the number of columns making up the table, a stored
location, and so on are set in the table information 225 for the
table. The column information 226 is likewise provided with
additional information when a table is created, and information
such as the name of the table organized of columns, names of
columns, data types of the respective columns, and so on are set in
the column information 226. The index information 227 is provided
with additional information when an index is produced, and
information such as the name(s) of a table and/or a column(s) for
which the index is created, and so on are set in the index
information 227.
[0074] The checked file list 228 is provided with additional
information from the check initiation processing unit 207, and a
check is made on files registered in the checked file list 228 by
the update check processing unit 209. Upon termination of the
check, the check termination processing unit 208 deletes
information corresponding to checked files on the checked file list
228.
[0075] The table data 223 stores data of respective created tables.
The select processing unit 203 retrieves column data; the insert
processing unit 202 stores row data; the update processing unit 204
rewrites column values; and the delete processing unit 205 deletes
a row.
[0076] The index data 224 is provided with additional information
when an index is created, and information 225 on a table for which
the index is created, column information 226, and so on are set in
the index data 224 for the index. When an index is created, index
data 224 is created and used to conduct a high speed select for
data which matches a select condition specified prior to the
execution of the select.
[0077] The journal file 121 in the disk drive 120 records the
contents of updates and deletes performed by requests of users such
that they would be used to recover the DB data 111 in case the DB
data 111 was destroyed by a fault or the like.
[0078] Next, description will be made on each of functions of the
DBMS 103 related to external file reference type data in the
database processing system of this embodiment. Operational
functions associated with the external file reference type data
include table definition, insert, select, update, delete, update
notice acceptance, and so on. In general, a processing request 210
is issued to the DBMS 103 which responsively executes operational
functions required for the processing request.
[0079] FIG. 4 illustrates an outline of table definition processing
according to this embodiment. FIG. 5 is a flow chart illustrating a
processing procedure for the table definition processing according
to this embodiment. The table definition processing will first be
described with reference to FIGS. 4 and 5.
[0080] In FIG. 4, a processing request 210 is sent to the DBMS 103
for specifying a table name 501 of a table to be created; column
names 502 of columns making up the table; data types 503 of the
respective columns; and so on. For allowing a column to reference
to an external file, an external file reference type is specified
in the data type 503 of the column.
[0081] The processing request acceptance processing unit 200 of the
DBMS 103 analyzes the processing request 210 accepted from the DB
client 130, runs the table definition processing unit 201 to add
the table name 501, the number of columns, and so on to the table
information 225 within the DB information 222, as well as add the
table name 501, the column names 502, and the column data types 503
to the column information 226 within the DB information 222 (step
401 in FIG. 5). When the external file reference type is specified
for any column data type 503, information indicative of the
external file reference type is added to the column information 226
(step 402).
[0082] FIG. 6 illustrates an outline of data insert processing
according to this embodiment. FIG. 7 is a flow chart illustrating a
processing procedure for the data insert processing according to
this embodiment. In the following, the data insert processing will
be described with reference to FIGS. 6 and 7.
[0083] In FIG. 6, a processing request 210 is sent to the DBMS 103
for specifying a table name 601 of a table into which data is
inserted; column data 602, 603 to be inserted into respective
columns; and so on. Data types set for data to be inserted include
integer type, text type, external data reference type, and so on.
To the column data 602, 603, data corresponding to their respective
types are allocated.
[0084] Referring now to FIG. 7, the processing request acceptance
processing unit 200 of the DBMS 103 analyzes the processing request
210 accepted from the DB client 130, and runs the insert processing
unit 202 to acquire table information 225, column information 226
and index information 227 corresponding to the table name 601 from
the DB information 222 (step 411), references the column
information 226, and stores the column data 602, 603 in
corresponding table data 223 in the DB data 111 (step 412).
[0085] If a journal output is specified (step 413), the stored
column data 602, 603 are outputted to the journal file 121 (step
414). If an inserted column is indexed (step 415), index
maintenance is executed (step 416).
[0086] FIG. 8 illustrates an outline of external file reference
type data insert processing according to this embodiment. FIG. 9 is
a flow chart illustrating a processing procedure for the external
file reference type data insert processing according to this
embodiment. In the following, an insert of external file reference
type data will be described with reference to FIGS. 8 and 9.
[0087] The DB client 130 specifies position information 604 and
watch information 605 as column data 603 when external file
reference type data is inserted.
[0088] The position information 604 specifies a storage location of
an external file to be referenced. This information may be
specified using URL for specifying the text data 143, 153 and image
data 144, 154 in the file servers 140, 150 which are connected to
the DB client 130 through the network 160.
[0089] The watch information 605 specifies the frequency of
watching the external file, and a watch processing unit responsible
for a watch. For example, since data recorded on a CD-ROM or the
like is not updated, the watch information 605 specifies READ ONLY
as the watching frequency for any file on a CD-ROM. If the external
file can be updated, the watch information 605 specifies the
watching frequency in hours, days, weeks, months, years, or the
like. In addition, when the DBMS update watch processing unit 145
is processing at a storage location at which an external file is
stored, the watch information 605 indicates that the external file
is a file under management of the DBMS update watch processing unit
145 as information indicative of a watch processing unit
responsible for a watch.
[0090] The processing request acceptance processing unit 200 of the
DBMS 103 analyzes the processing request 210 accepted from the DB
client 130, and runs the insert processing unit 202 of the DBMS
103, forcing the insert processing unit 202 to reference an
external file indicated by the position information 604 to check
the existence of the external file (step 451 in FIG. 9). When image
data 144 in FIG. 8 is specified as an external file, a data
transfer request is issued from the DBMS 103 based on the position
information 604 to the WWW server 141 (arrow 701 in FIG. 8),
forcing the WWW server 141 to transfer the image data 144 (arrows
702, 703). When text data 153 in FIG. 8 is specified in the
position information 604, a data transfer request is issued to the
WWW server 157 (arrow 711), forcing the WWW server 157 to transfer
the text data 153 (arrows 712, 713).
[0091] Next, at step 452, the watch information 605 is referenced
to check whether the external file is a file currently under
management of the DBMS update watch processing unit 145. When the
watch information 605 indicates that the external file is a file
currently under management of the DBMS update watch processing unit
145, the watch request processing unit 211 is run to issue an
external file watch request to the watch initiation processing unit
241 of DBMS update watch processing unit 145, with information on
the external file communicated to the watch initiation processing
unit 241 (step 453).
[0092] FIG. 10 is a flow chart illustrating a processing procedure
for the watch initiation processing according to this embodiment.
As can be seen in FIG. 10, the watch initiation processing unit 241
receives a watch request for requesting the same to watch an
external file, and registers the watched file list 148 with
information on the external file associated with the received watch
request (step 1501).
[0093] As a result of referencing the watch information 605 at step
452 in FIG. 9, when the external file is not a file under
management of the DBMS update watch processing unit 145, the watch
request processing unit 211 issues a request for a check on the
external file to the check initiation processing unit 207, with the
information on the external file communicated to the check
initiation processing unit 207 (step 454).
[0094] FIG. 11 is a flow chart illustrating a processing procedure
for the check initiation processing according to this embodiment.
As can be seen in FIG. 11, the check initiation processing unit 207
registers the checked file list 228 with the information on the
external file associated with the issued check request (step 1531),
acquires the external file and registers the checked file list 228
with a recent update time of the external file (step 1532), and
calculates the next check time from the watch frequency in the
watch information 605 and registers the checked file list 228 with
the calculated next check time (step 1533).
[0095] At step 456 in FIG. 9, the position information 604 and the
watch information 605 of the column data 603 are stored in the DB.
Next, it is checked whether or not a journal output is specified
(step 457). If so specified, the column data 603 and the acquired
external file are both outputted to the journal file 121 (step
458).
[0096] FIG. 12 illustrates an outline of data select processing
according to this embodiment. FIG. 13 is a flow chart illustrating
a processing procedure for the data select processing according to
this embodiment. In the following, the data select processing will
be described with reference to FIGS. 12 and 13.
[0097] In FIG. 12, a processing request 210 is sent to the DBMS 103
for specifying a table name 801 of a table to be retrieved, a
select item 802 and a select condition 803. The select item 802
specifies the name of a column to be retrieved, and an operation
performed on the column. When the column is specified as the
external file reference type, the processing request 210 can
specify a processing type indicating which of column data and the
contents of an external file are to be processed.
[0098] Referring now to FIG. 13, the processing request acceptance
processing unit 200 of the DBMS 103 analyzes the processing request
210 accepted from the DB client 130, runs the select processing
unit 203, forcing the select processing unit 203 to acquire table
information 225 corresponding to the table name 801, and column
information 226 specified in the select item 802 from the DB
information 222 (step 421), and acquires index information 227
associated with the select condition 803 from the DB information
222 (step 422).
[0099] Then, the select processing unit 203 fetches data of a
column specified in the select item 802 for a row which meets the
select condition 803 from table data 223 (step 423). In this event,
when the index information 227 available for the select condition
has been acquired at step 422, the index data 224 is used to
evaluate the condition. Conversely, if no index information 227 has
been acquired at step 422, the table data 223 is sequentially
referenced to evaluate the condition.
[0100] The data type of the select item is checked (step 424), and
if the column data type is other than the external file reference
type, the fetched column data 821 is transmitted to the DB client
130 (step 427).
[0101] If the column data type is the external file reference type,
the processing type is referenced to check which of the column data
and the contents of the external file are to be processed (step
425). If the column data is to be processed, positional information
823 and watch information 824 fetched from the DB data 111 are
transmitted to the DB client 130 (step 427). On the other hand, if
the contents of the external file are to be processed, external
file data is acquired based on the position information 823 fetched
from the DB data 111 (step 426), and the acquired data is
transmitted to the DB client 130 (step 427).
[0102] The acquisition of external file data is similar to a check
on the existence of a file in the insert processing. Specifically,
as illustrated in FIG. 8, a transfer request is issued to the WWW
server 141 or 157 corresponding to the position information 823,
causing WWW server 141 or 157 to transfer the requested data.
[0103] FIG. 14 illustrates an outline of column data update
processing according to this embodiment. FIG. 15 is a flow chart
illustrating a processing procedure for the column data update
processing according to this embodiment. In the following, the data
update processing will be described with reference to FIGS. 14 and
15. A processing request 210 is sent to the DBMS 103 for specifying
a table name 901 of a table to be updated, a column name 902 of a
column to be updated, update values 903 therefor, and so on.
[0104] The processing request acceptance processing unit 200 of the
DBMS 103 analyzes the processing request 210 accepted from the DB
client 130, and runs the update processing unit 204, forcing the
update processing unit 204 to acquire table information 225
corresponding to the table name 901, column information 226
corresponding to the column name 902 of the column which is
specified to be updated, and index information 227 from the DB
information 222 (step 431).
[0105] Next, the update processing unit 204 references the column
information 226 and the index information 227 to fetch column data
904 from the table data 223, and updates a column value in the
table data 223 with the update values 903 (step 432). At step 433,
it is checked whether or not a journal output is specified. If so
specified, the column value before the update and the column value
after the update are both outputted to the journal file 121 (step
434). At step 435, it is checked whether or not the updated column
is indexed. If indexed, the index maintenance processing unit 213
executes maintenance of the index data 224 (step 436).
[0106] FIG. 16 illustrates an outline of how watch processing is
terminated in external file change processing according to this
embodiment. More specifically, FIG. 16 represents the processing
for terminating the update watch processing or the update check
processing when column data to be updated is updated or a external
file to be referenced is changed.
[0107] FIG. 17 illustrates an outline of how the watch processing
is initiated in the external file update processing according to
this embodiment. With the external file reference type, position
information 1111, watch information 1112 and update type 1113 are
specified as update values 903, as can be seen in FIG. 17. The
values for the position information 1111 and the watch information
1112 are the same as those specified in the data insert processing.
The update type 1113 indicates which of column data and the
contents of an external file are to be processed.
[0108] When position information 1011 of column data to be updated
is updated to change an external file to be referenced, the update
watch processing or the update check processing on an external file
indicated by the position information 1011 of the column data 904
in FIG. 16 is terminated, and column values in the table data 223
are updated with the update values 903, followed by initiating the
update watch processing or the update check processing on an
external file indicated by the position information 1111 included
in the update values 903.
[0109] FIG. 18 is a flow chart illustrating a processing procedure
for the external data reference type column data update processing
according to this embodiment. The processing involved in changing
an external file to be referenced will be described in detail with
reference to FIGS. 16 to 18.
[0110] The processing request acceptance processing unit 200 of the
DBMS 103 analyzes a processing request 210 accepted from the DB
client 130, and runs the update processing unit 204, causing the
update processing unit 204 to reference an update type 1113 to
examine whether or not the processing request 210 is intended to
update the contents of an external file indicated by the position
information 1011 (step 470).
[0111] When the processing request 210 is not intended to update
the contents of the external file but to update the position
information 1011 to change an external file to be referenced, the
procedure proceeds to step 461, where the update processing unit
204 references watch information 1012 of the column data 904 to be
updated, which has been fetched from the table data 223, to check
whether or not the external file indicated by the position
information 1011 is a file currently under management of the DBMS
update watch processing unit 145 (step 461). If the external file
is a file currently under management of the DBMS update watch
processing unit 145, the watch termination notification processing
unit 212 is run to notify the DBMS update watch processing unit 145
that the watch is terminated (step 462).
[0112] FIG. 19 is a flow chart illustrating a processing procedure
for the watch termination processing according to this embodiment.
As can be seen in FIG. 19, the DBMS update watch processing unit
145, upon receipt of a watch termination notice, runs the watch
termination processing unit 242 to delete from the watched file
list 148 information on an external file associated with the
notified watch termination (step 1511).
[0113] Conversely, when the external file is not a file under
management of the DBMS update watch processing unit 145, the check
termination processing unit 208 is run through the watch
termination notification processing unit 212 (step 463).
[0114] FIG. 20 is a flow chart illustrating a processing procedure
for the check termination processing according to this embodiment.
As can be seen in FIG. 20, the check termination processing unit
208 deletes from the checked file list 228 information on an
external file associated with the notified check termination (step
1541).
[0115] Subsequently, the processing similar to the data insert
processing is executed to reference the specified position
information 1111, to check the existence of an external file
indicated by the position information 1111, and to acquire the
external file if it exists (step 464). The acquisition of external
file data is similar to a check which is made to see whether or not
a file exists during the insert processing. Specifically, as
previously shown in FIG. 8, a transfer request is issued to a WWW
server 141 or 157 corresponding to the position information 111,
causing the associated WWW server 141 or 157 to transfer the data
concerned.
[0116] Next, the watch information 1112 is referenced to check
whether or not the external file indicated by the position
information 1111 is a file currently under management of the DBMS
update watch processing unit 145 (step 465). When the external file
is a file currently under management of the DBMS update watch
processing unit 145, the watch request processing unit 211 is run
to communicate information on the external file to the watch
initiation processing unit 241 of the DBMS update watch processing
unit 145, and to request the watch initiation processing unit 241
to watch the external file (step 466). The watch initiation
processing unit 241 registers the watched file list 148 with the
information on the external file associated with the issued watch
request, as previously shown in FIG. 10 (step 1501).
[0117] Conversely, when the external file is not a file currently
under management of the DBMS update watch processing unit 145, the
watch request processing unit 211 is run to communicate the
information on the external file to the check initiation processing
unit 207 and to request the check initiation processing unit 207 to
check the external file (step 467 in FIG. 18). As previously shown
in FIG. 11, the check initiation processing unit 207 registers the
checked file list 228 with the information on the external file
associated with the issued check request (step 1531), acquires a
recent update time of the external file to register the acquired
recent update time in the checked file list 228 (step 1532), and
calculates the next check time from the watch frequency in the
watch information 1112 to register the calculated next check time
in the checked file list 228 (step 1533).
[0118] On the other hand, when the contents of an external file
referenced by column data is to be updated, the update processing
unit 204 acquires an external file indicated by the position
information 1111 in the update values 903 in FIG. 17, and changes
the external file indicated by the position information 1011 in the
column data 904 in FIG. 16 with the value of the acquired external
file.
[0119] Next, the processing involved in updating the contents of a
referenced external file will be described in detail with reference
to FIGS. 16 to 18. As the result of the examination at step 470 in
FIG. 18, which has been made with reference to the update type 1113
to see whether the processing request 210 is intended to update the
contents of an external file indicated by the position information
1011, when the processing request 210 is exactly intended to update
the contents of an external file, the contents of the external file
indicated by the position information 1011 is acquired, and stored
in the journal file 121. Then, a check is made on the existence of
an external file indicated by the position information 1111
specified in the update values 903, and the contents of the
external file are acquired if it exists (step 471).
[0120] The acquisition of external file data is similar to a check
on the existence of a file in the insert processing. Specifically,
as previously shown in FIG. 8, a transfer request is issued to a
WWW server 141 or 157 corresponding to the position information
1111, causing the associated WWW server 141 or 157 to transfer the
data concerned. Then, the acquired data is stored in the external
file indicated by the position information 1011 in the column data
904 (step 472). As described above, if a journal of an external
file to be updated has been acquired prior to an update, the
external file may be returned to the value before the update by
referencing the journal.
[0121] FIG. 21 illustrates an outline of data delete processing
according to this embodiment. FIG. 22 is a flow chart illustrating
a processing procedure for the data delete processing according to
this embodiment. The data delete processing will next be described
with reference to FIGS. 21 and 22.
[0122] A processing request 210 is sent to the DBMS 103 for
specifying a table name 1201 of a table to be deleted, a delete
condition 1202, and so on. When the table to be deleted includes
column data of external file reference type, the processing request
210 can specify a processing type to indicate which of column data
and the contents of an external file are to be processed.
[0123] The processing request acceptance processing unit 200 of the
DBMS 103 analyzes the processing request 210 accepted from the DB
client 130, runs the delete processing unit 205 to acquire table
information 225 corresponding to the table name 1201, column
information 226, and index information 227 associated with the
table from the DB information 222 (step 441) and to access the
table data 223 to delete data which meets the delete condition 1202
(step 442).
[0124] At step 443, it is checked whether or not a journal output
is specified. If so specified, the value before the delete is
outputted to the journal file 121 (step 444). At step 445, it is
checked whether or not the deleted table has included any indexed
column. If any indexed column is found, the index maintenance
processing unit 213 is run to execute maintenance of the index
(step 446).
[0125] FIG. 23 is a flow chart illustrating a processing procedure
for the data delete processing according to this embodiment. When a
table includes a column of external file reference type, the
processing type is checked as shown in FIG. 23 (step 481). If a
delete of stored column data 1203 is specified, watch information
1206 in the column data 1203 is referenced to check whether or not
an external file indicated by position information 1205 is a file
currently under management of the DBMS update watch processing unit
145 (step 482).
[0126] If the external file is a file currently under management of
the DBMS update watch processing unit 145, the watch termination
notification processing unit 212 is run to notify the DBMS update
watch processing unit 145 that the watch is terminated (step 483).
As previously shown in FIG. 19, the DBMS update watch processing
unit 145, upon receipt of the watch termination notice, runs the
watch termination processing unit 242 to delete from the watched
file list 148 information on the external file associated with the
watch termination notice received by the DBMS update watch
processing unit 145 (step 1511).
[0127] Conversely, if the external file is not a file currently
under management of the DBMS update watch processing unit 145, the
check termination processing unit 208 is run through the watch
termination notification processing unit 212 (step 484). As
previously shown in FIG. 20, the check termination processing unit
208 deletes from the checked file list 228 the information on the
external file associated with the watch termination notice received
by the DBMS update watch processing unit 145 (step 1541).
[0128] On the other hand, if a delete of an external file itself
indicated by the positional information 1205 has been specified at
step 481, the watch information 1206 in the column data 1203 is
referenced to check whether or not the external file is a file
currently under management of the DBMS update watch processing unit
145 (step 486).
[0129] If the external file is a file currently under management of
the DBMS update watch processing unit 145, the watch termination
notification processing unit 212 notifies the DBMS update watch
processing unit 145 that the watch is terminated (step 487). As
previously shown in FIG. 19, the DBMS update watch processing unit
145, upon receipt of the watch termination notice, runs the watch
termination processing unit 242 to delete from the watched file
list 148 information on the external file associated with the watch
termination notice received by the DBMS update watch processing
unit 145 (step 1511).
[0130] Conversely, if the external file is not a file currently
under management of the DBMS update watch processing unit 145, the
check termination processing unit 208 is run through the watch
termination notification processing unit 212 (step 488). As
previously shown in FIG. 20, the check termination processing unit
208 deletes from the checked file list 228 the information on the
external file associated with the watch termination notice (step
1541).
[0131] At step 485, the position information 1205 in the column
data 1203 is referenced to acquire the contents of an external file
indicated by the position information 1205. The external file is
deleted after it is stored in the journal file 121 (step 485). As
described above, when a journal of an external file to be deleted
has been acquired prior to a delete, the external file may be
returned to the value before the delete by referencing the
journal.
[0132] FIG. 24 illustrates an outline of the processing performed
by the I/O watch processing unit 243 according to this embodiment.
Update watch processing will next be described with reference to
FIG. 24. When an external file is inserted or updated under
management of the DBMS update watch processing unit 145 during the
insert processing or the update processing to a table including a
column of external file reference type, the DBMS 103 requests the
DBMS update watch processing unit 145 of a storage location, in
which external file reside, to initiate watching the external file.
Then, the watched file list 148 is registered with information on
the external file subjected to the requested watch.
[0133] FIG. 25 is a flow chart illustrating a processing procedure
for the I/O watch processing according to this embodiment. The I/O
watch processing unit 243 of the DBMS update watch processing unit
145 watches processing executed on the text data 143 and the image
data 144 in the file server 142. When such processing updates or
deletes an external file registered in the watched file list 148,
the I/O watch processing unit 243 sends to the DBMS 103 an update
notice indicating that the external file has been updated or
deleted.
[0134] The I/O watch processing unit 243 of the DBMS update watch
processing unit 145 sets an interrupt to input/output processing on
files in the file server 140 to watch the input/output processing
on the files. When a data access application 146 executes
input/output processing 1310 on the image data 144, a file I/O
interrupt 1320 is generated, causing the I/O watch processing unit
243 to check whether the executed input/output processing 1310
involves an update or a delete of a file concerned (step 1521).
[0135] When the input/output processing 1310 executed on the image
data 144 involves an update or a delete, the I/O watch processing
unit 243 checks whether or not the image data 144 subjected to the
input/output processing 1310 is included in a file registered in
the watched file list 148 (step 1522).
[0136] The I/O watch processing unit 243 transmits to the DBMS 103
an update notice 1330 indicating that the external file has been
updated or deleted when the image data 144 is included in a file
registered in the watched file list 148, and deletes information on
the external file from the watched file list 148 when the external
file has been deleted (step 1523). It should be noted that when the
external file is referenced by a plurality of tables, columns
and/or rows, the update notice 1330 is transmitted to all of
them.
[0137] FIG. 26 is a flow chart illustrating a processing procedure
for update notice acceptance processing according to this
embodiment. Upon receipt of the update notice 1330 from the I/O
watch processing unit 243, the DBMS 103 runs the update notice
acceptance processing unit 206, forcing the update notice
acceptance processing unit 206 to maintain respective information
such that the integrity of the DB data 111 managed by the DBMS 103
is not damaged by the updated external file.
[0138] The update notice acceptance processing will be described
below in greater detail. Since the update notice acceptance
processing unit 206 is run when an external file has been updated
or deleted, the update notice acceptance processing unit 206 first
checks whether update or delete has been executed (step 1610).
[0139] When an external file has been deleted, the update notice
acceptance processing unit 206 deletes a row corresponding to a
deleted column value (step 1615), checks whether or not an index is
registered in a table (step 1620), and instructs the index
maintenance processing unit 213 to execute maintenance processing
for the index if the index is registered in the table (step
1625).
[0140] When an external file has been updated, the update notice
acceptance processing unit 206 checks whether or not an index is
registered in a column which references the external file (step
1630), and instructs the index maintenance processing unit 213 to
execute maintenance processing for the index if the index is
registered in the column (step 1635).
[0141] FIG. 27 illustrates an outline of update check processing
according to this embodiment. FIG. 28 is a flow chart illustrating
a processing procedure for the update check processing according to
this embodiment. In the following, the processing performed by the
update check processing unit 209 will be described with reference
to FIGS. 27 and 28.
[0142] During insert processing or update processing on a table
including a column of external file reference type, when an
external file is inserted or updated as a file which is not under
management of the DBMS update watch processing unit 145, the check
initiation processing unit 207 registers the checked file list 228
in the DB information 222 contained in the DB data 111 with
information on an external file subjected to the requested check,
and a recent update time and next check time of the external
file.
[0143] The update check processing unit 209 references the checked
file list 228 to check whether a check time has reached for any
external file (step 1551), and references an external file, the
next check time of which has been passed by the current time, to
acquire a recent update time of the external file (step 1552).
[0144] Then, the update check processing unit 209 compares the
acquired recent update time with the preceding update time of the
external file previously registered in the checked file list 228
(step 1553). If the acquired recent update time has passed the
preceding update time, the update check processing unit 209
notifies the update notice acceptance processing unit 206 of an
update notice indicating that the external file has been updated
(step 1554), and registers the acquired recent update time again in
the checked file list 228 (step 1555).
[0145] At step 1556, the update check processing unit 209
calculates the next check time for the external file from the watch
frequency thereof, and registers the checked file list 228 with the
calculated next check time (step 1556), and repeats a check on the
checked file list 228 to see whether it came time to check any file
(step 1551).
[0146] When the external file has been deleted so that its recent
update time cannot be acquired at step 1552, the procedure proceeds
from step 1553 to 1561 where the update check processing unit 209
notifies the update notice acceptance processing unit 206 of an
update notice indicating that the external file has been deleted.
Then, at step 1562, the update check processing unit 209 deletes
external file information on the external file from the checked
file list 228.
[0147] Upon receipt of the update notice 1421 from the update check
processing unit 209, the update notice acceptance processing unit
206 performs external file update maintenance processing. As can be
seen in FIG. 26, since the update notice acceptance processing unit
206 is run when an external file has been updated or deleted, the
update notice acceptance processing unit 206 first checks whether
an update or a delete has been executed on the external file (step
1610). When an external file has been deleted, the update notice
acceptance processing unit 206 deletes a row corresponding to a
deleted value (step 1615), checks whether or not an index is
registered in a table (step 1620), and instructs the index
maintenance processing unit 213 to execute maintenance processing
for the index if the index is registered in the table (step 1625).
On the other hand, when an external file has been updated, the
update notice acceptance processing unit 206 checks whether or not
an index is registered in the column (step 1630), and instructs the
index maintenance processing unit 213 to execute maintenance
processing for the index if the index is registered in the column
(step 1635).
[0148] As described above, the database processing system according
to this embodiment detects an update or a delete performed on any
external file indicated by position information in column data
within a database, and updates the column data within the database
corresponding to processing performed on the external file, so that
data within external files placed outside the database can be
treated as data equivalent to ordinary column data stored in the
database itself, resulting in an improvement in the integrity of
the database.
[0149] Thus, according to the present invention, when an external
file indicated by position information in column data within a
database is updated or deleted, this processing is detected to
update the column data within the data base corresponding to the
processing performed on the external file, so that data within
external files placed outside the database can be treated as data
equivalent to ordinary column data stored in the database itself,
resulting in an improvement in the integrity of the database.
* * * * *