CN100397393C - Cursor processing system and method - Google Patents
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- CN100397393C CN100397393C CNB2004100868881A CN200410086888A CN100397393C CN 100397393 C CN100397393 C CN 100397393C CN B2004100868881 A CNB2004100868881 A CN B2004100868881A CN 200410086888 A CN200410086888 A CN 200410086888A CN 100397393 C CN100397393 C CN 100397393C
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Abstract
The invention discloses a cursor processing system which comprises a server-side cursor component, a query execution component and a query meta-operation execution component. Correspondingly, the invention also discloses a cursor processing method which comprises the following steps of 10) forming a query plan according to the definition of the cursor; step 20) decomposing the query plan into individual meta-operations and parameters and conditions related to each meta-operation; step 30) executing the meta-operations in sequence according to the parameters and conditions related to the meta-operations; step 40) judging whether a result is obtained; if a result is obtained, go to step 50) to return the obtained result to the cursor requester, otherwise go to step 60) to judge whether the table requested by the cursor has data; if yes, go to step 30), otherwise go to step 70) and end. The cursor processing system and the method can calculate a result and return the result to the user, so the cursor processing system and the method can improve the corresponding speed of the cursor and reduce the resource consumption.
Description
Technical field
The present invention relates to the Database Systems field, refer to a kind of cursor processing system and method especially.
Background technology
Because vernier can solve a SQL (the Sequential Quety Language of Database Systems, sequences query language) statement can obtain the multirow data and application program can only the single treatment data line mismatch problems, therefore nearly all Database Systems are all supported vernier at present.
In the relational database field, vernier is divided into service end vernier and client cursor.Wherein client cursor is to use local internal memory and temporary disc space to create in client; The service end vernier is to use temporary table or table space to create at server end.Except that client was criticized vernier, other client cursors were to submit information to server line by line, and are managed by client, also leave on the server in a large number.No matter be client cursor or server end vernier, all need store these result sets at server or client application resource, the different just positions of storage.
Be example with the service end vernier below, describe the vernier disposal route of prior art.As shown in Figure 1, comprising:
The step 1) server end receives the vernier request of application program, and the SQL statement in the described vernier request is extracted, and carries out SQL statement, calculates all results, generates result set;
Step 2) result set is stored in the interim result set heap (if result set is less, may a committed memory, otherwise must store in temporary table or the temporary file);
Step 3) is after result set generates, and server end informs that initiating vernier application requested vernier opens and finish;
The described application program of step 4) begins one by one to send to server end to obtain data command (in the realization that also has can once many);
After the step 5) server end receives and obtains data command, from result set, one by one the result is returned to described application program;
The described application program of step 6) is called and is closed the vernier order after finishing the vernier visit;
After the step 7) server end receives and closes the vernier order, discharge result set.
In sum, the vernier disposal route of prior art has following shortcoming:
One, under the bigger situation of result set, server or client need be stored a large amount of intermediate data (result set heap), can take a lot of external spaces like this, and the frequent access external memory can cause the cost of vernier to rise rapidly; If use the user of server cursor too much, can cause the resource exhaustion of temporary table on the server, and the CPU of server is proposed higher requirement.
Two, finish owing to always informing just after all results are calculated that the application program vernier is opened, that is to say and to wait until that all results calculate the back application program and can obtain the result, therefore, under the bigger situation of result set, application program just has to carry out very long wait, though first result of its demand calculates, have only after all results calculate, application program could obtain first result of its demand, its first trip data response times=whole vernier of calculating time+time of transmission article one data, so just cause the response time of reading first of vernier long.
Three, obtain first as a result the time when application program, all results calculate, if the user does not need total data, the calculating of being done has also just become idle work with storage work so.
Summary of the invention
The problem to be solved in the present invention provides and a kind ofly can improve the vernier response speed and reduce the cursor processing system that server resource expends.
In order to address the above problem, a kind of cursor processing system comprises server end cursor components, query execution component and inquiry unit operation executive module, wherein,
Described server end cursor components is used for according to vernier definition formation inquiry plan, and inquiry plan is sent to described query execution component, and the result of reception query execution component also returns this result;
Described query execution component, be used for inquiry plan is decomposed into unit's operation one by one and each first parameter and condition that relates to of operating, and unit operation and the parameter that relates to thereof and condition issued described inquiry unit operation executive module successively, receives the first execution result of operating executive module of described inquiry;
The first operation of described inquiry executive module is used for carrying out first the operation according to unit's operation related parameter and condition.
Further, cursor processing system of the present invention also comprises and being used for by the operation of described inquiry unit is carried out
Assembly is carried out the physics access element that the gained result locks and keeps data base consistency(-tance).
Further, cursor processing system of the present invention comprises that also being used to receive vernier defines and send it to
The client cursor assembly of server end cursor components.
The operation of described unit refers to not subdivisible operation
Correspondingly, a kind of vernier disposal route comprises:
Definition forms inquiry plan to step 10) according to vernier;
Step 20) inquiry plan is decomposed into one by one parameter that unit's operation and each unit's operation relate to and
Condition;
Step 30) parameter and the condition that relates to according to unit's operation carried out these yuan operation successively;
Step 40) judges whether to obtain a result;
If obtain a result, then forward step 50 to) acquired result is returned to the vernier requestor,
Otherwise forward step 60 to) judge whether also have data in the table that vernier asks;
If have, then forward step 30 to), otherwise forward step 70 to) finish.
Described step 10) is further divided into:
11) grammatical analysis is carried out in the vernier request and formed the query grammar parsing tree;
12) the query grammar parsing tree is carried out type checking and form query optimization tree with type information.
Described step 20) operation of unit described in refers to not subdivisible operation.
Compared with prior art, the beneficial effect of cursor processing system of the present invention:
Because query execution component is decomposed into first one by one operation and parameter and condition with inquiry plan, inquiry unit operation executive module is used to carry out unit's operation, promptly carry out operation to database table, therefrom take out a result, and this result passed to described query execution component, described query execution component sends to vernier requestor by server-side component with Query Result with this delivery server end assembly as a result.That is to say, whenever obtain a result, just this result is sent to the vernier requestor, and needn't wait until that all results obtain the back and sending to the vernier requestor successively, its first trip data response times=calculating vernier first line data time+time of transmission article one data, thereby improved the vernier response speed greatly.
Owing to just the result is sent to the vernier requestor after cursor processing system of the present invention is obtained a result, and does not need the space to store, can not expend the resource of server.
Owing to just the result is sent to the vernier requestor after cursor processing system of the present invention is obtained a result, if the vernier requestor no longer needs other result, just needn't go to calculate other result again, significantly reduced the expense of I/O and CPU like this.
Vernier disposal route in like manner of the present invention also has above-mentioned beneficial effect.
Description of drawings
Fig. 1 is the process flow diagram of prior art vernier disposal route;
Fig. 2 is the structural drawing of cursor processing system of the present invention;
Fig. 3 is that server end cursor components inquiry plan forms process flow diagram;
Fig. 4 is the process flow diagram that query execution component realizes;
Fig. 5 is the process flow diagram that inquiry unit operation executive module is realized;
Fig. 6 is the process flow diagram that the physics access element realizes;
Fig. 7 is the process flow diagram of vernier disposal route of the present invention.
Fig. 8 is unit's operation tree graph that second embodiment decomposes
Embodiment
As shown in Figure 2, cursor processing system of the present invention comprises server end cursor components 101, query execution component 102 and inquiry unit operation executive module 103, wherein,
Described server end cursor components 101 is used for forming inquiry plan according to the vernier request, and inquiry plan is sent to described query execution component 102, and the result of reception query execution component 102 also returns this result;
Described query execution component 102, be used for inquiry plan is decomposed into unit's operation one by one and each first parameter and condition that relates to of operating, and unit operation and the parameter that relates to thereof and condition issued described inquiry unit operation executive module 103 successively, receives the first execution result of operating executive module 103 of described inquiry; Described unit operation refers to not subdivisible operation, for example: basic selection operation, projection operation, sorting operation, attended operation, cartesian product operation, grouping and the aggregate function operation of the theoretical foundation stone relational algebra of relational database, eliminate repetitive operation, gather and the operation of reporting to the leadship after accomplishing a task, can repeat collection and report to the leadship after accomplishing a task operation and subquery are handled and operated etc.;
The first operation of described inquiry executive module 103 is used for carrying out first the operation according to unit's operation related parameter and condition.
Further, also comprise and being used for by described inquiry unit operation executive module 103 is carried out the physics access element 104 that the gained results lock and keep data base consistency(-tance).
Further, also comprise and be used to the client cursor assembly 105 that receives the vernier request and send it to described server end cursor components 101.
As shown in Figure 3, server end cursor components 101 comprises the syntax analyzer 1011 that is used to analyze vernier request grammer and form the query grammar parsing tree, forms the Type inspector 1012 of the query optimization tree with type information and the query optimizer 1013 of inquiry plan according to data dictionary and query grammar parsing tree.The type of each data item that uses in the described type information query optimization tree comprises the type of being supported in the OSCAR databases such as Int, Float, Char, Varchar.Described Type inspector 1012 checks that whether each data item that is occurred in the query optimization tree exists, and will check also as existing whether its type mates.
As shown in Figure 4, the realization flow of query execution component 102 is as follows:
Step 1021) inquiry plan is decomposed into parameter and the condition that unit's operation one by one and each unit's operation relate to;
Step 1022) takes out parameter and the condition that a unit operates and relates to, and it is passed to inquiry unit operation executive module 103;
Step 1023) judges whether to receive inquiry unit operation executive module 103 execution results;
If do not receive, step 1024 then) return no result to server end cursor components 101, otherwise step 1025) judge whether to also have the operation of unenforced unit;
If also have the operation of unenforced unit, then forward step 1022 to), otherwise step 1026) result is passed to server end cursor components 101.
As shown in Figure 5, the realization flow of inquiry unit operation executive module 103 is as follows:
Step 1030) sends request of data to physics access element 104;
Step 1031) judges whether to receive the data that physics access element 104 transmits;
If do not have, step 1032 then) return no result to query execution component 102, otherwise step 1033) carry out unit's operation;
Step 1034) judged whether filtercondition;
If do not have, step 1035 then) result is passed to query execution component 102, otherwise step 1036) carry out the filtercondition expression formula;
Step 1037) judges whether to satisfy filtercondition;
If do not satisfy, then forward step 1030 to), otherwise step 1038) result is passed to query execution component 102.
As shown in Figure 6, physics access element 104 realization flows are as follows:
Step 1040) judges whether the table that inquiry unit operation executive module 103 is asked also has data;
If do not have, step 1041 then) return no result to inquiry unit operation executive module 103, otherwise execution in step 1042) take out data;
Step 1043) data of being taken out is locked;
Step 1044) whether judgement locks successful;
If success, step 1045 then) result is passed to inquiry unit operation executive module 103, otherwise step 1046) wait for and obtain lock;
Step 1047) judges whether to obtain lock;
If not, step 1048 then) return to inquiry unit operation executive module 103 and make mistakes, otherwise step 1049) result is passed to inquiry unit operation executive module 103.
OSCAR database with the exploitation of visit Beijing softcom limited of divine boat is the technical scheme that example describes cursor processing system of the present invention in detail below.
This routine keeper will check the whole data that satisfy condition among the underlying table BASETABLE of OSCAR database.This table has 3,000,000 data approximately.
The vernier of keeper (DBA) definition is:
Declare?cursor?for?select*?from?basetable?where?bt_code?like‘330011％，。
(DBA checks the whole satisfied data that are numbered 330011 beginnings in the table possibly)
+----------------------------------------------------------------------------------------+
| QUERYPLAN |
+----------------------------------------------------------------------------------------+
| Seq?Scan?on?BASETABLE(cost＝0.00..4.01?rows＝1425537?width＝240) |
| Filter：(BT_CODE?LIKE?′330011％′) |
+----------------------------------------------------------------------------------------+
Annotate: this inquiry plan points out that this inquiry is to call one to select unit's operation, obtains data by Seq Scan (sequential scanning of table) from table BASETABLE, and service condition ' NT_CODE LIKE ' 330011% ' filters Query Result.Its operation cost is between the 0.00...4.01, and the result that may inquire is 1425537 row, and the mean breadth of every row is 240 bytes.
This inquiry plan is delivered to query execution component 102, and query execution component 102 is decomposed into a first parameter of operating to select and relate to this inquiry plan and is table BASETABLE and filtercondition ' BT_CODE LIKE ' 330011% '.Query execution component 102 is selected unit operation and the parameter that relates to is table BASETABLE and filtercondition ' BT_CODE LIKE ' 330011% ' passes to inquiry unit operation executive module 103, inquiry unit operation executive module 103 is obtained the data of showing among the BASETABLE to 104 requests of physics access element, physics access element 104 is taken out a basic tuple (Zhang San from this table, 01,19660901,0,7,330011660901055 ... .) operate executive module 103 for inquiry unit.103 pairs of these line data of inquiry unit operation executive module according to condition BT_CODE LIKE ' 330011% ' are selected, and this result satisfies filtercondition, then this result is returned to query execution component 102.Because this inquiry plan only is decomposed into unit's operation, promptly show and do not have the operation of unenforced unit, after so query execution component 102 obtains this result, this result is passed to server end cursor components 101, server end cursor components 101 is packaged into this result the form of bag again, issue client cursor assembly 105 by procotol, client cursor assembly 105 returns to the DBA instrument after the result is unpacked.
Provide the process that another embodiment: DBA checks the total data among the view V_Student_Course below.
The definition of view V_Student_Course:
create?view?V_Student_course?as?SELECT?STUDENT.SNAME，COURSE.CNAME?FROM?STUDENT?INNER?JOIN?ELECT?ONstudent.SNO＝elect.sno?INNER?JOIN?COURSE?ON?course.cno＝elect.cno；
This view dependency is in three base tables, and promptly STUDENT, COURSE and EJECT show, and are defined as follows:
CREATE TABLE STUDENT (--student's basic condition table
SNO CHAR (8),--student number
SNAME VARCHAR (16),--name
SDEPT VARCHAR (8),--place system
SAGE INT,--the age
SGENDER CHAR (1),--sex (' M ' expression man, ' F ' represents the woman)
SCREDIT NUMERIC (4,1) DEFAULT0,--total credit
PRIMARY?KEY(SNO))；
CREATE TABLE COURSE (--the curriculum information table
CNO CHAR (4),--course number
CNAME VARCHAR (64),--the course name
CDEPT VARCHAR (8),--what give a course is
CCREDIT NUMERIC (3,1),--credit
PRIMARY?KEY(CNO))；
DBA definition vernier is:
Declare?cursor?for?select*from?V_Student_Course。
(DBA checks the total data in the view possibly)
This vernier definition is sent to server end cursor components 101 by the form with network packet, by it is carried out grammatical analysis, server end cursor components 101 forms an inquiry plan for this vernier definition, and following table is to use explain to order a description of this inquiry plan that obtains in the OSCAR database.
explain?select*from?V_Student_Course；
QUERY?PLAN
Nested?Loop(cost＝0.00..28.45?rows＝1width＝110)
-＞ Nested?Loop(cost＝0.00..20.79?rows＝4?width＝52)
Join?Cond：(″outer″.SNO＝″inner″.SNO)
-＞ Index?Scan?using?STUDENT_PKEY?on?STUDENT
(cost＝0.00..3.71?rows＝4?width＝32)
-＞ Seq?Scan?on?ELECT?(cost＝0.00..4.12?rows＝12?width＝20)
-＞Index?Scan?using?COURSE_PKEY?on?COURSE(cost＝0.00..1.90
rows＝1?width＝58)
Index?Cond：(COURSE.CNO＝″outer″.?CNO)
Annotate: this inquiry plan points out that this inquiry is to call one to connect unit's operation, from the connection result of table STUDENT and table ELECT, obtain data line, from table COURSE, use the operation of selection unit to obtain data line then and mate, return after the success, otherwise continue.
As shown in Figure 8, inquiry plan is delivered to query execution component 102, and query execution component 102 is decomposed it with this inquiry plan and is:
Parameter is selected in first yuan of operation: table STUDENT, index STUDENT_PKEY.
Parameter is selected in second yuan of operation: table ELECT;
First yuan is operatively connected parameter: first yuan of result and second yuan of result that operation is selected that operation is selected, condition of contact is JOIN COND:(" outer " .SNO=" inner " .SNO), i.e. STUDENT.SNO=ELECT.SNO.
The ternary operation is selected, and parameter is table: COURSE, index COURSE_PKEY and index condition COURSE.CNO=" outer " .CNO, i.e. COURSE.CNO=ELECT.CNO.
Second yuan is operatively connected parameter: the result that first yuan of result who is operatively connected and ternary operation are selected, condition of contact be a sky.
After query execution component 102 obtains this line data, judge to also have the operation of unenforced unit, then unit's operation selection and parameter ELECT are passed to inquiry unit operation executive module 103, and obtain the data line (S0000001, C001,84.0) in this table.
Correspondingly, as Fig. 7, vernier disposal route of the present invention comprises:
Step 10) forms inquiry plan according to the vernier request;
Step 20) inquiry plan is decomposed into parameter and the condition that unit's operation one by one and each unit's operation relate to;
Step 30) parameter and the condition that relates to according to unit's operation carried out these yuan operation successively;
Step 40) judges whether to obtain a result;
If obtain a result, then forward step 50 to) acquired result is returned to the user, otherwise forward step 60 to) judge whether also have data in the table of being asked;
If have, then forward step 30 to), otherwise forward step 70 to) finish.
Further, described step 10) is further divided into:
11) grammatical analysis is carried out in the vernier request and formed the query grammar parsing tree;
12) the query grammar parsing tree is carried out type checking and form query optimization tree with type information.
Step 20) operation of unit described in refers to not subdivisible operation, as selection operation, attended operation etc.
Vernier disposal route of the present invention forms inquiry plan to vernier definition carrying out grammatical analysis, again inquiry plan is decomposed into parameter and condition that unit's operation one by one and each unit's operation relate to, carry out these yuan operation successively, and end product is returned, promptly obtain a result and just it is returned
The above only is the preferred implementation of cursor processing system of the present invention and method; should be understood that; for those skilled in the art; under the prerequisite that does not break away from cursor processing system of the present invention and method principle; can also make some improvements and modifications, these improvements and modifications also should be considered as the protection domain of cursor processing system of the present invention and method.
Claims (7)
1. a cursor processing system is characterized in that, comprises server end cursor components, query execution component and inquiry unit operation executive module, wherein,
Described server end cursor components is used for according to vernier definition formation inquiry plan, and inquiry plan is sent to described query execution component, and the result of reception query execution component also returns this result;
Described query execution component, be used for inquiry plan is decomposed into unit's operation one by one and each first parameter and condition that relates to of operating, and unit operation and the parameter that relates to thereof and condition issued described inquiry unit operation executive module successively, receives the first execution result of operating executive module of described inquiry;
The first operation of described inquiry executive module is used for carrying out first the operation according to unit's operation related parameter and condition.
2. cursor processing system as claimed in claim 1 is characterized in that, also comprises being used for by the first operation of described inquiry executive module is carried out the physics access element that the gained result locks and keeps data base consistency(-tance).
3. cursor processing system as claimed in claim 2 is characterized in that, also comprises the client cursor assembly that is used to receive the vernier definition and sends it to the server end cursor components.
4. as described any one cursor processing system of claim 1 to 3, it is characterized in that the operation of described unit refers to not subdivisible operation.
5. a vernier disposal route is characterized in that, comprising:
Definition forms inquiry plan to step 10) according to vernier;
Step 20) inquiry plan is decomposed into parameter and the condition that unit's operation one by one and each unit's operation relate to;
Step 30) parameter and the condition that relates to according to unit's operation carried out these yuan operation successively;
Step 40) judges whether to obtain a result;
If obtain a result, then forward step 50 to) acquired result is returned to the vernier requestor, otherwise forward step 60 to) whether in addition judge in the table that vernier asks data;
If have, then forward step 30 to), otherwise forward step 70 to) finish.
6. vernier disposal route as claimed in claim 5 is characterized in that, described step 10) is further divided into:
11) grammatical analysis is carried out in the vernier request and formed the query grammar parsing tree;
12) the query grammar parsing tree is carried out type checking and form query optimization tree with type information.
7. as claim 5 or 6 described vernier disposal routes, it is characterized in that step 20) described in unit operation refer to not subdivisible operation.
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| CN102707956B (en) * | 2012-05-18 | 2015-12-16 | 北京工业大学 | Probabilistic method is returned results for the treatment of trigger |
| CN106021940B (en) * | 2016-05-26 | 2018-08-31 | 上海联影医疗科技有限公司 | Medical system and its execution method |
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| US6728721B1 (en) * | 2000-06-23 | 2004-04-27 | Microsoft Corporation | System and method for maintaining a user's state within a database table |
| US6728700B2 (en) * | 1996-04-23 | 2004-04-27 | International Business Machines Corporation | Natural language help interface |
| CN2643402Y (en) * | 2003-07-22 | 2004-09-22 | 无敌科技(西安)有限公司 | Chinese character inquiry device for various foreign languages |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6728700B2 (en) * | 1996-04-23 | 2004-04-27 | International Business Machines Corporation | Natural language help interface |
| US6728721B1 (en) * | 2000-06-23 | 2004-04-27 | Microsoft Corporation | System and method for maintaining a user's state within a database table |
| CN2643402Y (en) * | 2003-07-22 | 2004-09-22 | 无敌科技(西安)有限公司 | Chinese character inquiry device for various foreign languages |
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