CN101093501A - Method for querying high performance, transparent distributed spatial database - Google Patents

Abstract

A high efficient and transparent querying-method of distributed space databank includes dividing space topology relation operation and space analysis operation separately to be two types by utilizing space topology relation and space analysis operation as basis, dividing connection mode of space section on two said operations to be four types, providing three rules to be satisfied by cross-boundary connection operation of four-type space section and providing seven regulations of cross-boundary space section connection optimization mode based on three said rules.

Description

A kind of efficient, transparent distributed spatial database querying method

Technical field

The present invention relates to a kind of efficient, transparent distributed spatial database querying method, belong to message area.

Background technology

At present, realize that the cross-border seamless inquiry of distributed spatial database mainly contains two kinds of methods: the allocation rule that the first connects by the traditional distributed database is converted into the attended operation of each fragment with global query's attended operation, but efficiency of query is low; Another kind method is to determine correlativity between the place by the user, promptly determine by the user which relevant local place inquiry is sent to, this mode does not meet the requirement of the distributed data base transparency, and determine the intersite data dependence by user oneself, use complicated, in fact also unrealistic.

Summary of the invention

The purpose of this invention is to provide a kind of efficient, transparent distributed spatial database querying method, the query decomposition that is used for distributed space data by the cross-border connection principle of optimality that will propose, automatically generate the spatial sub inquiry that the local space database can be carried out, reach efficient, transparent seamless inquiry.

For realizing that the technical scheme that the object of the invention adopted is: a kind of efficient, transparent distributed spatial database querying method, pass through query decomposition, the data localization, global query optimization, four levels of local query optimization are realized, at the cross-border seamless inquiry problem of the distributed spatial database of cutting apart burst, earlier the attended operation of space fragment is classified, spatial topotaxy operation and spatial analysis operation based on Open GIS standard definition, spatial topotaxy operation is divided into from operation (Disjoint operation) with non-from operating (non-Disjoint operates), spatial analysis operation is divided into buffer operation (Buffer operation) and non-buffer operation (non-Buffer operation), and the connected mode of space fragment is divided into four classes according to spatial topotaxy operation and spatial analysis operation: first kind space fragment be connected be non-buffering inquire about non-from connection; The second space-like fragment connect be non-buffering inquiry from connection; It is the non-from connection of band buffering inquiry that the 3rd space-like fragment connects; The 4th space-like fragment connect be the inquiry of band buffering from connection, the incidence relation that spatial topotaxy operation, spatial analysis operation are connected with the space fragment has tentatively been made in this classification in order, for space segment sheet connection optimization is laid a good foundation.

Cutting apart on the cross-border seamless inquiry question essence of burst is cross-border space fragment connectivity problem, therefore can realize by the optimization that the space fragment connects.Cross-border fragment connects the basic thought of optimizing: the one, reduce space fragment number of connection; The 2nd, reduce participating in the object number that the space fragment connects, reduce the time of attended operation like this, also reduce the transmission quantity of intersite spatial data simultaneously.According to described two kinds of basic thoughts, two space fragments that following rule: I. satisfies first kind connected mode are satisfied in the dissimilar cross-border attended operations of space fragment must hand over rectangle intersection with the minimum outsourcing rectangle (MBR) of these two space fragment partitioning boundaries; II. the minimum outsourcing rectangle of the d buffer zone expansion of a space fragment relation does not exceed the d expansion of the minimum outsourcing rectangle of this space fragment partitioning boundary, and the d expanded definition of so-called minimum outsourcing rectangle is as follows: the lower left corner and the upper right corner coordinate of establishing the minimum outsourcing rectangle of a spatial object are respectively (x _Min, y _Min), (x _Max, y _Max), then the d of the minimum outsourcing rectangle of this object expansion is that the lower left corner and upper right corner coordinate are respectively (x _Min-d, y _Min-d), (x _Max+ d, y _Max+ d) rectangle, wherein d is an arithmetic number; III. two intersegmental the 3rd space-likes of spatial pieces connect, if satisfy the 3rd class connected mode of space fragment between main leaf section object and auxilliary fragment objects, the object that then satisfies the 3rd space-like topological relation in the main leaf section intersects with the d expansion of the minimum outsourcing rectangle of auxilliary fragment or two d expansions of minimum outsourcing rectangle, main leaf section wherein, auxilliary fragment, the definition of two d expansions is as follows respectively: the fragment that comprises buffer operation in two fragments that participate in connecting is called the main leaf section, then another fragment claims auxilliary fragment, if on two fragments that participate in connecting buffer operation is arranged all, if buffer zone is respectively d1, d2, then choose one wantonly as the main leaf section, another is as auxilliary fragment, carry out the d1+d2 expansion of minimum outsourcing rectangle to any one fragment this moment, is called two d expansions of fragment;

Based on three above-mentioned rules, the method that fragment cross-border connection in space is optimized is proposed, comprise that 3 are removed rule: if the minimum outsourcing rectangle of the partitioning boundary of two space fragments that participation connects is non-intersect, then the intersegmental first kind connection of these two spatial pieces is removed (1); (2) non-conterminous space fragment first kind connection is removed; (3) expand non-intersect if cut apart the broad sense d of two space fragments of burst, then intersegmental the 3rd class of these two spatial pieces connects removal, the broad sense d expanded definition of so-called junction fragment is as follows: participate in the fragment X that buffering connects, its broad sense d expansion table is shown MBR (X) _ d _EIf, do fragment again after the advanced row buffering operation of the object among the X and connect, then d equals the buffer zone distance, i.e. MBR (X) _ d _E=MBR (X) _ d connects if the object among the X directly carries out fragment, then regards d=0 as, at this moment MBR (X) _ d _E=MBR (X); And following 4 connection transformation rules: (4) carry out the cross-border θ of the first kind on two space fragment X, Y _Sp-1 ^EdConnect, be converted to earlier and hand over rectangle to ask friendship to filter, and then carry out first kind spatial join operation θ based on X, the minimum outsourcing rectangle of Y partitioning boundary carrying out on X, the Y _Sp-1, that is: $X{\∞}_{{\mathrm{\θ}}_{\mathrm{sp}-1}^{\mathrm{ed}}}Y={\mathrm{\σ}}_{{\mathrm{\θ}}_{\mathrm{sp}-1}^f}\left(X\right){\∞}_{{\mathrm{\θ}}_{\mathrm{sp}-1}}{\mathrm{\σ}}_{{\mathrm{\θ}}_{\mathrm{sp}-1}^f}\left(Y\right);$ (5) if the minimum outsourcing rectangle of the partitioning boundary of two space fragments that participation connects is non-intersect, then the second intersegmental class of these two spatial pieces connects the cartesian product that is converted into these two fragments; (6) on two space fragment X, Y, carry out the cross-border connection of the 3rd class θ _Sp-3 ^Ed, be converted to and on X, carry out earlier the 3rd space-like topology filtration θ _{MBR (Y) _ d} ^f(X), filter result is carried out the d buffering, and then carry out the 3rd space-like attended operation θ _Sp-3, promptly ${\mathrm{\η}}_d\left(X\right){\∞}_{{\mathrm{\θ}}_{\mathrm{sp}-3}^{\mathrm{ed}}}Y={\mathrm{\η}}_d\left({\mathrm{\σ}}_{{\mathrm{\θ}}_{\mathrm{MBR}\left(Y\right)\_d}^f}\left(X\right)\right){\∞}_{{\mathrm{\θ}}_{\mathrm{sp}-3}}Y;$ (7) the broad sense d expansion of two space fragments of participation connection is non-intersect, and then these two intersegmental connections of spatial pieces are converted into the cartesian product of these two space fragments.

A kind of efficient, transparent distributed spatial database querying method provided by the invention, realize that by query decomposition, data localization, global query optimization, four levels of local query optimization step is as follows:

Query decomposition: the inquiry problem is converted to a relational algebra expression formula that is defined on the holotopy, query decomposition was four steps: the first step is write inquiry as normalized form, second step was that the standardization query statement is carried out the correctness analysis, the 3rd step was to inquire about abbreviation, the 4th step was that query statement is rewritten as an algebraically inquiry, query rewrite is divided into two sub-steps: the one, query conversion is become relational algebra, and the 2nd, relational algebra inquiry reconstruct;

Data localization: by DATA DISTRIBUTION information locating query data, the fragment that relates in determining to inquire about, inquiry on the holotopy is specialized, inquire about specific to localization or on the space fragment on changing with advancing, relational algebra expression formula on the holotopy is transformed to relational expression on respective segments, utilize 7 rules of the cross-border connection optimization of space fragment to optimize space querying, removing the unnecessary non-conterminous space fragment first kind according to the removal rule (1) in the cross-border connection optimization method of space fragment and (2) is connected, connect the principle of optimality (3) according to the space fragment and remove intersegmental the 3rd class connection of sheet, and whether adjacent by from the global catalog of space, obtaining fragment, information such as the minimum outsourcing rectangle of fragment are judged the optimization of using four kinds of which kind of principles of optimality that connects in the transformation rule to carry out space fragment connection;

Global query optimization: be bordering on optimized implementation strategy by seeking one, promptly find out the optimum operation order of burst inquiry, comprise the cost function minimum, cost function generally is I/O, CPU and communication cost sum, an output relational algebra inquiry optimization, on the fragment;

Local query optimization: on each website, carry out subquery by each website that has query fragment, adopt the integrated system algorithm to be optimized by the DBMS on this website.

The invention has the beneficial effects as follows: on traditional transparent query processing basis, connect the principle of optimality by the cross-border fragment that proposes and realized connection optimization between the segment of space having realized inquiring about efficiently, pellucidly distributed spatial database.

Embodiment

The concrete steps of query decomposition, data localization, global query optimization, four levels of local query optimization are as follows:

Query decomposition: the inquiry problem is converted to a relational algebra expression formula that is defined on the holotopy.Query decomposition was divided into for four steps: the first step is write inquiry as normalized form, so that subsequent treatment; Second step was that the standardization query statement is carried out the correctness analysis; The 3rd step was to inquire about abbreviation, eliminated redundant predicate; The 4th step was that query statement is rewritten as an algebraically inquiry, and query rewrite is divided into two sub-steps: the one, query conversion is become relational algebra, and the 2nd, relational algebra inquiry reconstruct is explained with query tree.When the reconstruct of relational algebra inquiry, realize part optimization by the transformation rule of traditional database, comprise and eliminate redundancy etc.This layer of required information of conversion obtains in global concept schema.

The data localization: this layer input is the algebraically inquiry on the distributed holotopy, by DATA DISTRIBUTION information locating query data, determine to relate to which fragment in the inquiry, the inquiry on the holotopy is specialized, implement to the inquiry on the suitable fragment.Relational algebra expression formula with on the holotopy is transformed to the relational expression on respective segments.

Utilize the space fragment to connect 7 rules optimizing and optimize space querying.In traditional distributed data base, there are many unnecessary connections in the connection between the horizontal fragmentation fragment, cuts apart the segmentation that obtains by same minute cut set, has unnecessary connection equally.Removing the unnecessary non-conterminous space fragment first kind according to the removal rule (1) in the space fragment connection optimization method with (2) is connected, remove intersegmental the 3rd class connection of sheet according to removing regular (3), and by the optimization that obtains from the global catalog of space whether fragment adjacent, four kinds of which kind of rules that connects in the transformation rule of the information such as MBR of fragment judgement utilization are carried out space fragment connection.

Global query optimization: the input of global optimization is the fragment inquiry, the i.e. inquiry of algebraically on fragment, purpose is to seek one and is bordering on optimized implementation strategy, just look for the optimum operation order of burst inquiry, comprise the cost function minimum, cost function generally is I/O, CPU and communication cost sum.The output of global query is the relational algebra inquiry on an optimization, the fragment.This layer of required information comprises each place fragment statistical information, resource information and the communication information etc. from statistics of database information.

Local query optimization: carry out subquery by each website that has query fragment on each website, it adopts the integrated system algorithm to be optimized by the DBMS on this website, and information needed is taken from local mode.

The present invention will be further described below in conjunction with embodiment.

Embodiment 1

The concrete execution in step of an experimental system is:

(1) system call: the user should overall situation SQL statement pass to the distributed space data access engine after input SQL statement on the query interface.

(2) global query decomposes: distributed query was divided into for two steps, and the first step realizes the parsing of SQL query statement, obtains syntax tree; Second step was carried out conversion to syntax tree, obtained the merger threaded tree.

(3) data localization and query optimization: the merger threaded tree is carried out localization and optimizes according to information such as place bursts, call global catalog's service, be used for obtaining necessary global information in data localization and the optimization procedures, as the selectivity factor of fragment place, statistical information, attended operation etc., utilize and remove rule and be connected the optimization that transformation rule has been realized space fragment connection.Removing the unnecessary non-conterminous space fragment first kind according to removal rule (1) with (2) is connected; Remove intersegmental the 3rd class of sheet and connect according to removing rule (3), and by obtain from the global catalog of space whether fragment adjacent, the information such as MBR of fragment judge that four kinds of which kind of rules that connects in the transformation rule of utilization carry out the space fragment and connect and optimize.

(4) query scheduling; After the distributed space data access engine obtains the query execution plan tree, query execution plan tree and corresponding with it scheduling script are sent on the dispatch server, dispatch server comes the operation dispatching script by distributed script engine, tree is carried out in inquiry travel through, the acting server that each execution node sends on the relevant execution place is carried out.After all finishing, final query results is returned to the distributed space data access engine.

(5) execution of execution node: after acting server obtains to carry out node, characteristics according to its data source, carry out the fragment query conversion, and call the visit of relevant local space database engine and basic data and drive and inquire about, after obtaining data set, same form according to the native system regulation carries out serializing, at last the result is sent to appointed positions.

Claims (2)

1. One kind efficient, transparent distributed spatial database querying method, pass through query decomposition, the data localization, global query optimization, four levels of local query optimization are realized, it is characterized in that: at the cross-border seamless inquiry problem of the distributed spatial database of cutting apart burst, earlier the attended operation of space fragment is classified, spatial topotaxy operation and spatial analysis operation based on the OpenGIS standard definition, the spatial topotaxy operation is divided into from operating with non-from operation, spatial analysis operation is divided into buffer operation and non-buffer operation, and the connected mode of space fragment is divided into four classes according to spatial topotaxy operation and spatial analysis operation: first kind space fragment be connected be non-buffering inquire about non-from connection; The second space-like fragment connect be non-buffering inquiry from connection; It is the non-from connection of band buffering inquiry that the 3rd space-like fragment connects; The 4th space-like fragment connect be the inquiry of band buffering from connection, this classification has been set up spatial topotaxy operation, spatial analysis operation and the incidence relation between the space fragment is connected, on this basis, following rule is satisfied in the cross-border attended operation of dissimilar space fragment:

   I. satisfy two space fragments of first kind connected mode and must hand over rectangle intersection with the minimum outsourcing rectangle of these two space fragment partitioning boundaries;

   II. the minimum outsourcing rectangle of the d buffer zone expansion of a space fragment relation does not exceed the d expansion of the minimum outsourcing rectangle of this space fragment partitioning boundary, and the d expanded definition of so-called minimum outsourcing rectangle is as follows: the lower left corner and the upper right corner coordinate of establishing the minimum outsourcing rectangle of a spatial object are respectively (x _Min, y _Min), (x _Max, y _Max), then the d of the minimum outsourcing rectangle of this object expansion is that the lower left corner and upper right corner coordinate are respectively (x _Min-d, y _Min-d), (x _Max+ d, y _Max+ d) rectangle, wherein d is an arithmetic number;

   III. two intersegmental the 3rd space-likes of spatial pieces connect, if satisfy the 3rd class connected mode of space fragment between main leaf section object and auxilliary fragment objects, the object that then satisfies the 3rd space-like topological relation in the main leaf section intersects with the d expansion of the minimum outsourcing rectangle of auxilliary fragment or two d expansions of minimum outsourcing rectangle, main leaf section wherein, auxilliary fragment, the definition of two d expansions is as follows respectively: the fragment that comprises buffer operation in two fragments that participate in connecting is called the main leaf section, then another fragment claims auxilliary fragment, if on two fragments that participate in connecting buffer operation is arranged all, if buffer zone is respectively d1, d2, then choose one wantonly as the main leaf section, another is as auxilliary fragment, carry out the d1+d2 expansion of minimum outsourcing rectangle to any one fragment this moment, is called two d expansions of fragment;

   Based on these three rules, 7 rules that fragment cross-border connection in space is optimized are proposed, remove rule comprising following 3:

   (1) if the minimum outsourcing rectangle of the partitioning boundary of two space fragments that participation connects is non-intersect, then the intersegmental first kind of these two spatial pieces connects removal;

   (2) non-conterminous space fragment first kind connection is removed;

   (3) expand non-intersect if cut apart the broad sense d of two space fragments of burst, then intersegmental the 3rd class of these two spatial pieces connects removal, the broad sense d expanded definition of so-called junction fragment is as follows: participate in the fragment X that buffering connects, its broad sense d expansion table is shown MBR (X) _ d _EIf, do fragment again after the advanced row buffering operation of the object among the X and connect, then d equals the buffer zone distance, i.e. MBR (X) _ d _E=MBR (X) _ d connects if the object among the X directly carries out fragment, then regards d=0 as, at this moment MBR (X) _ d _E=MBR (X);

   And following 4 connection transformation rules:

   (4) on two space fragment X, Y, carry out the cross-border θ of the first kind _Sp-1 ^EdConnect, be converted to earlier and hand over rectangle to ask friendship to filter, and then carry out first kind spatial join operation θ based on X, the minimum outsourcing rectangle of Y partitioning boundary carrying out on X, the Y _Sp-1, that is: ${X\∞}_{{\mathrm{\θ}}_{\mathrm{sp}-1}^{\mathrm{ed}}}Y={\mathrm{\σ}}_{{\mathrm{\θ}}_{\mathrm{sp}-1}^f}\left(X\right){\∞}_{{\mathrm{\θ}}_{\mathrm{sp}-1}}{\mathrm{\σ}}_{{\mathrm{\θ}}_{\mathrm{sp}-1}^f}\left(Y\right);$

   (5) if the minimum outsourcing rectangle of the partitioning boundary of two space fragments that participation connects is non-intersect, then the second intersegmental class of these two spatial pieces connects the cartesian product that is converted into these two fragments;

   (6) on two space fragment X, Y, carry out the cross-border connection of the 3rd class θ _Sp-3 ^Ed, be converted to and on X, carry out earlier the 3rd space-like topology filtration θ _{MBR (Y) _ d} ^f(X), filter result is carried out the d buffering, and then carry out the 3rd space-like attended operation θ _Sp-3, promptly ${\mathrm{\η}}_d\left(X\right){\∞}_{{\mathrm{\θ}}_{\mathrm{sp}-3}^{\mathrm{ed}}}Y={\mathrm{\η}}_d\left({\mathrm{\σ}}_{{\mathrm{\θ}}_{\mathrm{MBR}\left(Y\right)\_d}^f}\left(X\right)\right){\∞}_{{\mathrm{\θ}}_{\mathrm{sp}-3}}Y;$

   (7) the broad sense d expansion of two space fragments of participation connection is non-intersect, and then these two intersegmental connections of spatial pieces are converted into the cartesian product of these two space fragments.
2. 2. a kind of efficient, transparent distributed spatial database querying method according to claim 1 is characterized in that: the concrete steps that query decomposition, data localization, global query optimization, four levels of local query optimization are realized are as follows:

   Query decomposition: the inquiry problem is converted to a relational algebra expression formula that is defined on the holotopy, query decomposition was four steps: the first step is write inquiry as normalized form, second step was that the standardization query statement is carried out the correctness analysis, the 3rd step was to inquire about abbreviation, the 4th step was that query statement is rewritten as an algebraically inquiry, query rewrite is divided into two sub-steps: the one, query conversion is become relational algebra, and the 2nd, relational algebra inquiry reconstruct;

   Data localization: by DATA DISTRIBUTION information locating query data, the fragment that relates in determining to inquire about, inquiry on the holotopy is specialized, inquire about specific to localization or on the space fragment on changing with advancing, relational algebra expression formula on the holotopy is transformed to relational expression on respective segments, utilize 7 rules of the cross-border connection optimization of space fragment to optimize space querying, removing the unnecessary non-conterminous space fragment first kind according to the cross-border connection principle of optimality of space fragment (1) and (2) is connected, connect the principle of optimality (3) according to the space fragment and remove intersegmental the 3rd class connection of sheet, and whether adjacent by from the global catalog of space, obtaining fragment, information such as the minimum outsourcing rectangle of fragment are judged the optimization of using four kinds of which kind of principles of optimality that connects in the transformation rule to carry out space fragment connection;

   Global query optimization: be bordering on optimized implementation strategy by seeking one, promptly find out the optimum operation order of burst inquiry, a relational algebra inquiry optimization of output, on the fragment;

   Local query optimization: on each website, carry out subquery by each website that has query fragment, adopt the integrated system algorithm to be optimized by the DBMS on this website.