Query method and query device
A query method and a query device, where the method includes determining N execution plans respectively corresponding to N query requests according to the received N query requests, determining at least two same first sub-plans, generating a first sub-query result corresponding to any one of the at least two same first sub-plans, and in a process of generating, according to the N query requests, a query result corresponding to each of the N query requests, the same first sub-query result corresponding to any one of the first sub-plans is used for all the same first sub-plans. Hence, a large amount of repeated calculation can be reduced, database system resources are reduced, and query efficiency and a throughput of a database system in a large-scale concurrent query application scenario are improved.
1. A query method, comprising:
receiving N query requests, wherein the N comprises a positive integer greater than one;
determining N execution plans according to the N query requests, wherein the N execution plans correspond one-to-one to the N query requests, and wherein each of the N execution plans comprises a plurality of sub-plans;
determining at least two same first sub-plans, wherein the at least two same first sub-plans comprise different or same execution plans in the N execution plans;
generating a first sub-query result corresponding to any one of the at least two same first sub-plans, wherein the first sub-query result is used for all the at least two same first sub-plans;
determining at least two mutually different second sub-plans, wherein the at least two mutually different second sub-plans comprise different or same execution plans in the N execution plans;
generating second sub-query results separately corresponding to the at least two mutually different second sub-plans;
generating, based on the first sub-query result and the second sub-query results, a query result corresponding to each of the N query requests; and
setting, after generating the first sub-query result corresponding to any one of the at least two same first sub-plans, a hyperlink in each of the at least two same first sub-plans, wherein the hyperlink indicates all same first sub-plans.
2. The query method of claim 1 , wherein determining the N execution plans comprises:
determining a first query request set, wherein the first query request set comprises at least one of the N query requests, wherein an execution plan corresponding to each query request in the first query request set is stored in a plan cache, and wherein the plan cache stores an execution plan corresponding to the at least one of the N query requests; and
obtaining the execution plan stored in the plan cache corresponding to each query request in the first query request set.
3. The query method of claim 1 , wherein determining the N execution plans comprises:
determining a second query request set, wherein the second query request set comprises at least one of the N query requests, wherein an execution plan corresponding to each query request in the second query request set is not stored in a plan cache, and wherein the plan cache stores an execution plan corresponding to the at least one of the N query requests; and
generating the execution plan corresponding to each query request in the second query request set.
4. The query method of claim 1 , wherein before receiving the N query requests, the query method further comprises:
determining M query requests, wherein the M comprises a positive integer greater than one;
calculating total duration in which M query results are generated according to the M query requests, wherein the M query results respectively correspond to the M query requests;
determining average query duration based on the total duration in which the M query results are generated according to the M query requests;
determining a preset time period, wherein the preset time period is less than the average query duration; and
receiving the N query requests in the preset time period.
5. The query method of claim 1 , wherein receiving the N query requests comprises:
determining whether a quantity of received query requests is less than a target quantity;
continuing to receive a query request when the quantity of received query requests is less than the target quantity; and
avoid receiving any more query requests when the quantity of received query requests is greater than or equal to the target quantity.
6. The query method of claim 1 , wherein after generating the first sub-query result, the query method further comprises allocating a same address in a data cache to all the at least two same first sub-plans, and wherein the data cache stores the first sub-query result corresponding to any one of the at least two same first sub-plans.
7. The query method of claim 1 wherein setting the hyperlink in each of the at least two same first sub-plans comprises setting the hyperlink in a highest-level operator of each of the at least two same first sub-plans, and wherein each of the at least two same first sub-plans comprises a plurality of operators coupled according to an execution sequence, a lower-level operator outputting a calculation result to an upper-level operator, and the highest-level operator of each of the at least two same first sub-plans comprising a last operator executed in each of the at least two same first sub-plans.
8. The query method of claim 1 wherein after setting the hyperlink in each of the at least two same first sub-plans, the query method further comprises allocating a same address in a data cache to hyperlinks set in all the at least two same first sub-plans.
9. A query device, comprising:
an input/output interface configured to receive N query requests, wherein the N comprises a positive integer greater than one; and
a central processing unit (CPU) coupled to the input/output interface and configured to:
determine N execution plans according to the N query requests, wherein the N execution plans correspond one-to-one to the N query requests, and wherein each of the N execution plans comprises a plurality of sub-plans;
determine at least two same first sub-plans, wherein the at least two same first sub-plans comprises different or same execution plans in the N execution plans;
generate a first sub-query result corresponding to any one of the at least two same first sub-plans, wherein the first sub-query result is used for all the at least two same first sub-plans;
determine at least two mutually different second sub-plans, wherein the at least two mutually different second sub-plans comprise different or same execution plans in the N execution plans;
generate second sub-query results separately corresponding to the at least two mutually different second sub-plans;
generate, based on the first sub-query result and the second sub-query results, a query result corresponding to each of the N query requests; and
set a hyperlink in each of the at least two same first sub-plans, wherein the hyperlink indicates all same first sub-plans.
10. The query device of claim 9 , wherein the CPU is further configured to:
determine a first query request set, wherein the first query request set comprises at least one of the N query requests, wherein an execution plan corresponding to each query request in the first query request set is stored in a plan cache, and wherein the plan cache stores an execution plan corresponding to the at least one of the N query requests; and
obtain the execution plan stored in the plan cache corresponding to each query request in the first query request set.
11. The query device of claim 9 , wherein the CPU is further configured to:
determine a second query request set, wherein the second query request set comprises at least one of the N query requests, wherein an execution plan corresponding to each query request in the second query request set is not stored in a plan cache, and wherein the plan cache stores an execution plan corresponding to the at least one of the N query requests; and
generate the execution plan corresponding to each query request in the second query request set.
12. The query device of claim 9 , wherein the CPU is further configured to:
determine M query requests, wherein the M comprises a positive integer greater than one;
calculate total duration in which M query results are generated according to the M query requests, wherein the M query results respectively correspond to the M query requests;
determine average query duration, wherein the average query duration comprises the total duration in which the M query results are generated according to the M query requests;
determine a preset time period, wherein the preset time period is less than the average query duration; and
receive the N query requests in the preset time period.
13. The query device of claim 9 , wherein the CPU is further configured to:
determine whether a quantity of received query requests is less than a target quantity;
continue to receive a query request when the quantity of received query requests is less than the target quantity; and
avoid receiving any more query requests when the quantity of received query requests is greater than or equal to the target quantity.
14. The query device of claim 9 , wherein the CPU is further configured to allocate a same address in a data cache to all the at least two same first sub-plans, and wherein the data cache stores the first sub-query result corresponding to any one of the at least two same first sub-plans.
15. The query device of claim 9 wherein the CPU is further configured to set the hyperlink in a highest-level operator of each of the at least two same first sub-plans, wherein each of the at least two same first sub-plans comprises a plurality of operators coupled according to an execution sequence, wherein a lower-level operator outputs a calculation result to an upper-level operator, and wherein the highest-level operator of each of the at least two same first sub-plans comprises a last operator executed in each of the at least two same first sub-plans.
16. The query device of claim 9 , wherein the CPU is further configured to allocate a same address in a data cache to hyperlinks set in all the at least two same first sub-plans.
17. A computer program product comprising instructions stored on a non-transitory computer-readable medium that, when executed by a processor, cause a query device to:
receive N query requests, wherein the N comprises a positive integer greater than one;
determine N execution plans according to the N query requests, wherein the N execution plans correspond one-to-one to the N query requests, and wherein each of the N execution plans comprises a plurality of sub-plans;
determine at least two same first sub-plans, wherein the at least two same first sub-plans comprise different or same execution plans in the N execution plans;
generate a first sub-query result corresponding to any one of the at least two same first sub-plans, wherein the first sub-query result is used for all the at least two same first sub-plans;
determine at least two mutually different second sub-plans, wherein the at least two mutually different second sub-plans comprise different or same execution plans in the N execution plans;
generate second sub-query results separately corresponding to the at least two mutually different second sub-plans;
generate, based on the first sub-query result and the second sub-query results, a query result corresponding to each of the N query requests; and
set, after generating the first sub-query result corresponding to any one of the at least two same first sub-plans, a hyperlink in each of the at least two same first sub-plans, wherein the hyperlink indicates all same first sub-plans.
18. The computer program product of claim 17 , wherein the instructions cause the query device to determine the N execution plans by:
determining a first query request set, wherein the first query request set comprises at least one of the N query requests, wherein an execution plan corresponding to each query request in the first query request set is stored in a plan cache, and wherein the plan cache stores an execution plan corresponding to the at least one of the N query requests; and
obtaining the execution plan stored in the plan cache corresponding to each query request in the first query request set.
19. The computer program product of claim 17 , wherein the instructions cause the query device to determine the N execution plans by:
determining a second query request set, wherein the second query request set comprises at least one of the N query requests, wherein an execution plan corresponding to each query request in the second query request set is not stored in a plan cache, and wherein the plan cache stores an execution plan corresponding to the at least one of the N query requests; and
generating the execution plan corresponding to each query request in the second query request set.
20. The computer program product of claim 17 , wherein before receiving the N query requests, the instructions cause the query device to:
determine M query requests, wherein the M comprises a positive integer greater than one;
calculate total duration in which M query results are generated according to the M query requests, wherein the M query results respectively correspond to the M query requests;
determine average query duration based on the total duration in which the M query results are generated according to the M query requests;
determine a preset time period, wherein the preset time period is less than the average query duration; and
receive the N query requests in the preset time period.