CN1125991A

CN1125991A - A method of attaining data access in a primary memory based database

Info

Publication number: CN1125991A
Application number: CN94192575A
Authority: CN
Inventors: B·M·森米尔逊
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 1993-06-23
Filing date: 1994-06-17
Publication date: 1996-07-03
Also published as: NO955276L; SE501433C2; SE9302175D0; KR960703251A; EP0705460A1; WO1995000907A1; FI956243A; SE9302175L; FI956243A0; BR9406910A; JPH08512151A; NO955276D0; CA2165774A1; AU7088894A

Abstract

When an object (18) in a primary memory based data base is accessed by a user, there is created in the user process (14) an agent object (16), that contains a reference to the real object (18), and appears as if it were the real object. All accesses to the data of the object (18) are performed by reading directly, via the reference (20) in the agent object, in the memory of the storage manager. The data accesses are performed via a generic interface (12), in the form of read and write operations towards attributes.

Description

A kind of to carry out the method for data access based on the database of primary memory

Technical field of the present invention

The present invention relates to a kind of to carry out the method for data access based on the database of primary memory, described database has one and has comprised an operating system that has the storage manager of a storer, and the data in the described database are organized as the data entity that comprises attribute and method.

The data entity here is meant and may be an entity of a kind of object in the OO data system.

When a user (client computer) visits based on object in the database of primary memory, be by someway data being sent to user's processing procedure from database.

Application code is the storer of accessing database directly, because there is the danger that is destroyed data by rewriting.Correlation technique is introduced

Being generally used for the method that data send application program to is to create a backup in the private memory of user procedures.Then, just as the management to the object of its programming language of adaptation in the user procedures, promptly it may read the data of this object and call method in this object to the management of this object.Only when this object was rewritten back in the database, the modification (if there is) of carrying out in this object was only visible concerning revising user procedures.

At US5,043, introduce one in 869 and be used for a memory construction of having used the message handler of object oriented programming languages. in this case, program is to data in the object and process, to the visit of object, for example transmission of message is by the addressing of a list object is finished. in list object, show the address of the object that is arranged in another storage area, in program implementation, will from object, repeatedly read.In order in the situation of frequent access, to improve processing speed, be added in the list object about some information of object.Like this, in another storage area different with the storage area of storage object, set up a tabulation about object, it has comprised the partial information of the reference of object about object.

EP, A2,117,906 relate to the constituent act in the computer system.This computer system has comprised a primary memory and second memory.These files are divided into two ranks: one has comprised that the data level that is stored in the message block in the second memory and one when using file, are contained in the index level in the primary memory.When file was not used, this two-stage all was stored in the second memory.In the time need conducting interviews to an end of second memory, will use index level, it has comprised the reference key input of message block of the second memory at memory page place.Like this, index level has comprised the information of the object that relates to second memory, to reduce the access time.

EP, A2,381,447 relate to a kind of time method that reduces reference-to storage.In order to improve performance of computer systems, when a plurality of user is especially arranged, use virtual memory addressing (virtual memory system) usually in system.If several programs want to visit simultaneously a memory area,, then there is the danger that clashes if the addressing of storer is carried out according to actual physical address.Can imagine that different programs carries out write and read to same address, may bring the destruction to data, virtual addressing is meant that it just is the actual physical address of this object in the storer as this address that program conducts interviews to the object in the storer.In fact, a unit is arranged between processor and storer, it is virtual address translation a physical address.This unit can also carry out intermediary's storage of these addresses, can be several program organization addressing.This illustrates that each program is just internal as having only a program in the homologous ray and deposits into capable addressing.

Like this, can finish visit by rank in the middle of certain as can be known by above file to memory area.In first file, obtain the address of an object by calling a list object; In second file, used an index level to realize to being stored in the visit of the relative section in the second memory; In the end in file, used a virtual address, it is changed by a unit between processor and storer, to realize the direct visit to storer.Brief summary of the present invention

An object of the present invention is to provide a kind of method of introducing previously, it provides the performance than prior art advanced person, is opening the short response time, and is not needing database is carried out any duplicating after modification.

The method according to this invention has been opened a consumer process, and provides a general-purpose interface for this consumer process.This consumer process is when conducting interviews to a data entity in the database, to in consumer process, set up an agent entity that has comprised a reference of this True Data entity, and assign it as this True Data entity, and all visits to the data of this data entity all are directly to read in the storer of storage manager by described reference.Read-write operation is to operate on the attribute of this data entity by described general-purpose interface to finish.

Like this, in other words, it is right the user data entity in the database to be conducted interviews, and will create an agent entity in a consumer process, and it has comprised a reference of this True Data entity.This agent entity just looks like that this True Data entity is the same, finishes but all visits to the data of this data entity are the storeies that directly read this storage manager by the reference of this storage.Data access is by a general-purpose interface, finishes in the mode of attribute being carried out the read and write operation.

Many useful embodiment of the present invention are described below.

The opening operation that is used to open this data entity can comprise, for this consumer process distributes a pointer that points to this agent entity, this agent entity has an illustrated interface in the data entity type description of the data entity of this data entity of this True Data entity.

Can create this agent entity to generate the reference as pointer, this pointer is realized with reference to effective and efficient manner so that check.

The code that is used for the method for this data entity can realize by a dynamic link mechanism relevant with creating agent entity, and the permission consumer process is opened this data entity and need not be known the classification sign indicating number of this data entity.

This agent entity can directly read the data of this data entity from the memory area of storage manager.

Can call storage manager and be transformed into management mode to cause, run time version has the right of the All Ranges of the storer of processor being carried out write operation in this pattern, and consumer process can only be visited its proprietary memory area.

In data definition language (DDL), can produce a description of structure that is used for the code of agent entity and has comprised the data-base recording of data entity according to a data entity type specification of data entity, this storage manager uses this to describe the data of managing this data entity.

Storage manager can be discerned the attribute that needs visit by agent entity.

In the code that produces, can comprise calling to general-purpose interface, come the identification data attributes of entities with attribute code in general-purpose interface, in the interface of the agent entity that has produced, used Property Name identified during identical attribute can be described with this data entity type with plain language.

Can an attribute be described with data definition language (DDL), point out its title and type, and in the code that produces, can provide this attribute with two kinds of functions, a kind of being used to reads, a kind of being used to write, use the title identical with illustrated attribute, different functions is returned the acceptable value separately with the type same type of this attribute of having illustrated.

In the description to the structure of the data-base recording that is loaded into storage manager, identical attribute can be described by the dimension information of the storage space of an attribute code and a correspondence and illustrated type.The accompanying drawing summary

To further be described the present invention with embodiment and with reference to accompanying drawing now, accompanying drawing has:

Fig. 1 illustrated according to the present invention a visit based on the data of database of primary memory in the mode of block scheme,

Fig. 2 illustrates the logical OR virtual address space in the distributed memory environment, and the storage manager of data is operated therein.

Fig. 3 illustrates according to the present invention in the mode of block scheme, is used for the generation of the code of the agent object that a consumer process creates.Detailed description of preferred embodiment

Data in the database that goes wrong (being pointed out by 2 among Fig. 1 and Fig. 2 usually) are organized as the data entity that has comprised attribute and method.Among the embodiment that is described below, suppose in a data entity and the object-oriented system one to as if the same.

The notion of the object here has the common implication in the data processing technique.Briefly, one to as if a packets of information that has relevant description how to manage its information.Data in the object can directly read also and can read by the method in the allocating object.The scope that object (also being data recording) uses according to them is divided into class, and is identified by key word.Can be about the more detailed description of object notion referring to " object oriented analysis " write such as Peter Coad and Edward Yourdon, series is calculated by Yourdon publishing house.

Database has comprised a storage manager that moves 4 in having the environment of distributed primary memory, logical address space shown in Fig. 2, the dedicated memory area 6 that in this space, has been each course allocation, 6 ', 6 " ... or the like, in each private memory, its process has the power of read and write; and to public part database 2 for example, the power of reading of code 8 and operating system data 10.In logical address space, in the local storage of some process, can have identical address, but these addresses are that map is to the different addresses of physical storage.For public part, all processes all have the identical map between logic and physical address.

For user's's (client computer) process provides the ability of the read-only power that can not write of the storage area of database has been guaranteed, realized visit an object according to method of the present invention (describing in detail below).

Storage manager 4 as the part of operating system for application program provides a general-purpose interface 12, is also referred to as DMI interface (DMI=database manager interface) below, and this interface can be used by all users.This DMI interface has the low layer characteristic and does not have the type protection mechanism.

All data accesses all are to realize by opening an object.The input data of opening operation are object types, the type that object is conducted interviews that primary key and user are required.When carrying out opening operation, locate this object by primary key, and provide the current type of a locking for it.Whether and checking has other process using this object.

The result of opening operation is that consumer process 14 is received a pointer 15 that points to an agent object 16.This agent object 16 has the interface with real object, but without any attribute that this object had.But this agent object 16 has comprised the reference of data of this object of data record 18 that is arranged in database 2.This agent object 16, conducts interviews to data-base recording 18 attribute is carried out the mode of reading and writing operation by general-purpose interface 12.The reference of data-base recording 18 comes down to a pointer 20, and it can be with checking whether effective and efficient manner realizes in this reference.

Mode by dynamic link mechanism (it allows the user to open an objects stored, and does not need the code chain of the type of opened object is received in identical the insmoding) visits the code of the method for this object.Link combines with the formation agent object and forms.

Dynamic link mechanism also allow to open to as if one open the desired special case of process.More specifically, method and attribute that this definite opened object can have the process of opening not know, and also the method known to it can embody rather than in the mode of basic class with another kind of method.Process visits the code of this certain object type by dynamic link mechanism, and client code is being compiled and be connected not needing to know the code of this certain object type.

Agent object 16 is also referred to as " DOA " (data object agency) below, and the function of storage manager is divided into as the lower part:---an interface 22, back are called " DOI " (data object proxy interface).---the type control in the DOI interface.---hiding of attribute code.---the execution of the modification of two-way reference.---hiding of distribution and addressing.---" trigger ", the example of carrying out when promptly user-defined incident in certain definition takes place

Journey is normally to the modification of an attribute of an objects stored.---with being connected of each processing.

Further describe the function of DMI interface 12 now, as mentioned above, object is not sent to consumer process 14 when visit, but create an agent object 16, it is the data 18 of this object of visit from the memory section of storage manager 4 directly.In order to prevent this point, consumer process 14, requires to finish this visit by the routine of calling in the storage manager 4 by the data in the write operation destruction database 2 owing to some misprogrammed.Storage manager 4 can be found whether consumer process 14 are attempted one be not opened and carries out write operation with the object of making an amendment then, can finish to be called the mode that trap calls calling of storage manager 4, and its makes and is converted to supervisor mode.The code of carrying out in supervisor mode can write all sites of computer memory, and consumer process 14 can only be visited its all dedicated memory area 6.

Like this, the code of storage manager 4 and interface 12 must be general, will be applicable to all object types that will be managed in other words, and those object types that also do not know the details when design stores manager 4.Because this reason has been created an interface 12, make the operation of DMI can manage all types of objects that will be stored in the database 2, and without any need for about the description of data type and the knowledge of semantics aspect.Like this, DMI interface 12 has a low-level characteristic, makes it be unsuitable for direct DLL (dynamic link library) as Application Design.

The previous hereinbefore concept type protection of using is a notion in the programming language, is meant that compiler can check that variable uses whether logically in whole procedure.Programmer illustrates that the data of which kind of type will be stored in the variable.By type definition, determine to be stored in the description and the explanation of the information in the variable.Usually to carry out type declaration to variable, constant and function parameters in the program and rreturn value.

These explanations make compiler use variable according to the mode of expection.For example a function parameter is contemplated to be a character string, will not allow an integer to be used for this parameter so.

Now by based on of the present invention be used for visiting with the method for the data of management database 2 do more detailed description, and have the part false code.For the ease of illustrating the clear following routine of using:

In each incident,

1; Indication is followed by note,

2; Indication is followed by personal code work,

3; Indication is the code that generates subsequently, and

4; Indication is followed by the versatility code in the storage manager.

Read access

1; Suppose object type Person is included in the database.With object of following way access:

2; Person ∷ Open Dirsy Read (value of＜primary key 〉) ∥ points to the class methods of a generation.(C++ grammer)

3; Class methods are called the general of DMI interface and are opened--method parameter: and the value of object type sign indicating number and primary key, the object type sign indicating number is encoded into opening of generation--in the method.

4; Storage manager is searched the current object in index location by one.Pointer (i.e. the physical address of Ding Wei data-base recording) is put in the table, and inspection of this table and index return to the deployment method of generation.Data-base recording comprises a reference of a class object, and this reference comprises a pointer that points to the DOA Class Designer again.By this method, in the memory area of consumer process, created a DOA object of a true class.In the DOA object, stored the inspection and the index of address table.The pointer that points to the DOA object is returned to deployment method.

3; Deployment method returns to the user with this pointer.

1; The DOA object is just as the agency of objects stored now.Visit to the attribute in the object " sizes of footwear " is finished in the following way:

2; The size of the size of footwear=Person DOA → footwear

3; Attribute " sizes of footwear " in the DOA object, by a method with identical name explanation.This method call DMI operation is read property value by parameter programming and address table index.

4; Storage manager is by address table location database record and return the property value of pointing out.

3; DOA calls this and returns client computer.

Revise

1; Object type Person is arranged in the tentation data storehouse, and begun a processing.Modification to an object is finished as follows:

2; Person ∷ OpenUpdate (＜primary key value 〉,＜handle Id 〉) ∥ points to the class methods that generate.(C++ grammer)

3; Class methods are called the general deployment method parameter of DMI interface: handle ID, and object type sign indicating number and primary key value, the object type sign indicating number is encoded in the general deployment method.

4; Storage manager is searched index by one and is located problematic object.In the storage space of storage manager, create the duplicate of this data-base recording.A pointer, promptly the physical memory address of this duplicate is put in the table, and return the inspection and the index of this table for the deployment method that generates, this data-base recording has comprised a reference of a class object, and this reference comprises a pointer that points to the DOA Class Designer.By this method, in the storage area of user processor, created a DOA object of a true class.In the DOA object, stored the inspection and the index of address table.The pointer that points to the DOA object returns to deployment method.

3; Deployment method returns to client computer with this pointer.

1; The DOA object can use as the agency of objects stored now.The branch of the value of the attribute in the object " sizes of footwear " is equipped with following method to be finished:

2；PersonDOA→Size?of?shoe-pwt(47)

3; Attribute " sizes of footwear " in the DOA object by a method explanation that name is identical.The value of attribute is revised in this method call DMI operation by parameter attribute sign indicating number and address table index.

4; Storage manager is located the copy of modification by address table, and is the attribute assignment numerical value of appointment.

3; DOA will call and turn back to the user

1; Is constant and visible in order to make this modification to other process, comprises that its processing must " be preengage ".This process is roughly as follows:

2；trRef→commit

4; Handling manager is that reservation is ready by writing in daily record etc., if this processing is to be distributed in also will carry out a 2PC agreement in several processors, after this, duplicate and original paper is exchanged to make that amended object becomes visible.Handle manager and in DOA, carry out back reservation triggers for all objects in this processing.

3; This trigger method belongs to DOA.

4; Handle manager and lock is opened and removed this DOA object.Turn back to client computer.

Example

2; Person ∷ Create (＜primary key value 〉,＜handle Id 〉) ∥ points to the class methods that generate.(C++ grammer)

3; The general deployment method parameter of such method call DMI interface: handle Id, object type sign indicating number and primary key value, the object type sign indicating number has been coded in the deployment method of generation.

4; Storage manager keeps the primary key value of this object.In the storage space of storage manager, generated a data-base recording, but it is not connected with a pointer, duplicate physical memory address is put in the table in other words, and inspection of this table and index is returned to the deployment method of generation.This data-base recording has comprised the reference of a class object, and it comprises the pointer that points to the DOA Class Designer again.By this method, in the memory area of consumer process, generated the DOA object of a real class.In this DOA object, storing the inspection and the index of this address table.Return the pointer that points to this DOA object and give deployment method.

3; Deployment method returns to client computer with this pointer.

1; This DOA object now just can be as the agency of objects stored.Be " sizes of footwear " this attribute assignment numerical value in this object by the following method:

2；PersonDOA→Size?of?shoe-puf(47)

3; In this DOA object, with identical name attribute " sizes of footwear " is described by a method.This method is called the DMI operation to revise the value of attribute with parameter attribute sign indicating number and address table index.

4; Storage manager is located the duplicate of modification by address table, and is the attribute assignment numerical value of indication.

3; DOA calls this and returns to the user.

1; In order to make that this modification is reliable and visible to other process, comprise that the processing of this modification must " be preengage ".It is carried out as top described in the modification of object.

Be description below to the back-up system function.

With reference to Fig. 3, the coding of this agent object generates with a kind of established data definitional language from an object type describer 24.Be used for the description that a compiler 26 of this language also produces the structure of this data recording, storage manager 4 uses this to describe the data of managing this object.The description of this data structure and this DOA coding are encapsulated in the loading module that can be loaded in the system.Below that detailed description is mentioned coding maker.

As mentioned above, objects stored writes down as data in storage manager 4 and manages, and the user then is described as an agent object 16.Hypothesis storage manager 4 is known the structure of this object like this, i.e. the attribute of its storage, and also this agent object can identify the attribute that it will be visited concerning storage manager.This can be realized by compiler by data definition language (DDL).

Can write out the routine explanation of an object type by data definition language (DDL).By this explanation, generate a description that can be loaded into the data structure of storage manager 4, arrow 28 on the one hand; Be that agent object 16 generates coding, arrow 30 on the other hand.In the code that generates, comprised one to the calling of DMI interface 12, discern the attribute of this object by attribute code at this.In the DOI interface 22 that generates, identical attribute by in the ordinary language in explanation employed attribute-name discern.

After in data definition language (DDL) an attribute being described, its title and type have just been specified.In generating code, this attribute has the title identical with the attribute of explanation and shows as two kinds of functions, and a kind of being used to reads, and a kind of being used to write, and illustrated same type in the attribute type explanation is returned or accepted to described function respectively.In the data structure that is loaded into storage manager 4 was described, this identical attribute description was an attribute code and the dimension information corresponding to the shared storage space of type of this explanation.

The invention provides performance benefit, specifically when the smaller portions of an object being carried out read access and revising.When opening, the short response time occurs, and after once revising, do not need to copy to database again, and this object is always all in database.

Owing to finish all write operations by interface 12, rather than directly in archival memory, write, just avoided application code when write operation, to destroy other object except that accessed object unintentionally by application code to storage manager 4.

This scheme also provides method for some functions with the difficult realization of other method:

--trigger

Because all are to finish by the interface 22 of agent object 16 toward the write operation in the database, so object type and the attribute that has trigger can be provided.This trigger can be operated by DOI and finish, and calls except carrying out a DMI, and promptly one by the calling of interface 12, and also carries out the code of trigger of the part of this agent object 16.

--the MOSI interface

Have an object that is called MOSI interface (management object supporting interface) in order to use with a general utility tool that is used for user interface, to provide.This interface has comprised the parameter that is used for access attribute and carries out the method for object, is operated by a general object administration agent.Method in the MOSI interface has comprised that one is produced by compiler 26, recognizes the mapping of inner identification from the outside.

Claims

1, is used for obtaining to an a kind of method based on the data access of the data of the database of primary memory, described database has one and has comprised an operating system that has the storage manager of storer, and described data of database is with the form tissue of the data entity that comprised attribute and method

Described method comprises

Open a consumer process, for described consumer process provides a general-purpose interface,

By following steps, a data entity from described consumer process accessing database,

In consumer process, create an agent entity that has comprised a reference of True Data entity, and this agent entity regarded the True Data entity,

By described reference, will all finish the all-access of the data of data entity by the storer that directly reads storage manager, and

Finish read and write operation by described general-purpose interface to the attribute of data entity.

2, based on a kind of method of claim 1, comprised and carried out an opening operation that is used to open described data entity, be included as described consumer process and distribute a pointer that points to described agent entity, an interface that has the True Data entity is as illustrated at a data entity type specification that is used for described data entity.

3,, comprise and create described agent entity that this pointer is can check whether available method realizes in this reference to form the described reference of a pointer-type based on a kind of method of claim 2.

4, based on a kind of method of any claim in front, comprise the step of a code that obtains the method for data entity with a dynamic link mechanism of carrying out in conjunction with forming described agent entity (it is carried out and creates described agent entity associated), and allow described consumer process to open described data entity and do not need to know the class coding of this data entity.

5,, comprise the data that allow this agent entity directly from the memory area of storage manager, to read this data entity based on a kind of method of any claim in front.

6, based on a kind of method of any claim in front, comprise and call described storage manager, so that be transformed into supervisor mode, run time version has the ability of being had living space of the storer that writes processor in supervisor mode, and consumer process only can be visited its dedicated memory area.

7, based on a kind of method of any claim in front, be included as described agent entity and produce a code from data entity type specification of described data entity with a kind of data definition language (DDL), and a description, and be used in described description by described storage manager the data of data entity are managed the structure of a data-base recording having comprised described data entity.

8,, comprise by providing the attribute of wanting to visit to make storage manager identify agent entity based on a kind of method of claim 7.

9, based on a kind of method of claim 7, be included in the generating code that calls general-purpose interface, the identification of the attribute of data entity is by attribute code, is to discern by the attribute-name of using in the data entity type is described with ordinary language to the identification of identical attribute in the generation interface of agent entity.

10, based on a kind of method of claim 9, comprise with data definition language (DDL) and an attribute is described by the title and the type of specifying an attribute, this attribute has two kinds of functions in generating code, a kind of being used to reads, a kind of being used to write, what use is identical title used in the attribute specification, and described function is returned respectively and accepted with the type that illustrates in the attribute specification is the numerical value of type.

11, based on a kind of method of claim 10, be included in the explanation to the structure of the data-base recording that is loaded into storage manager, same alike result is described with relevant dimension information so that an attribute code and storage with this explanation type are empty.

12, based on a kind of method of any claim in front, said data entity is the object in the object-oriented data system.