Query processing with specialized query operators
Queries targeting various data sources are processed in a query processing pipeline that parses the query into a set of operations (e.g., an expression tree or a translated SQL query) using a set of query operators, each handling a particular type of operation. The query operators are often designed in an unspecialized manner, such that each query operator handles one query operation in an atomic, generic manner (e.g., sorting generic data items for an ORDER BY clause.) More efficient queries may be devised by including specialized queries that operate in common but special cases, such as a sorting of a particular data type (e.g., a floating-point number sort) or a sequence of two or more operations that are often performed together (e.g., a WHERE test of an attribute followed by a SELECT of the same attribute.) The use of specialized operators may result in the formulation of more efficient queries.
1. A system for generating a query processing solution for a query involving a data set on a device having a processor and a memory, comprising:
a query operator set comprising:
at least one single-task query operator comprising instructions stored in the memory that, when executed on the processor, cause the device to perform a query task on the data set, and
at least one multiple-task query operator comprising instructions stored in the memory that, when executed on the processor, cause the device to perform at least one query task and at least one additional query task on the data set; and
a query operator selecting component comprising instructions stored in the memory that, when executed on the processor, cause the device to:
for respective query terms:
for respective multiple-task query operators:
determine whether the at least one additional query task of the multiple-task query operator is also to be performed on the data set, and
upon determining that the at least one additional query task is also to be performed on the data set, select the multiple-task query operator for applying the query task and the at least one additional query task to the data set; and
upon failing to select a multiple-task query operator for the query term, select an single-task query operator for applying the query task to the data set; and
generate the query processing solution as a sequence of selected query operators.
2. The system of claim 1 , the query comprising a language-integrated query.
3. The system of claim 1 , the query comprising an in-memory query against at least one queryable local object.
4. The system of claim 1 , the query processing solution comprising an expression tree specifying the sequence operators corresponding to the query terms of the query.
5. The system of claim 1 , the query operator set further comprising at least one specialization criterion of a specialized query operator specifying at least two query tasks specified in at least two query terms.
6. The system of claim 5 , the instructions of the query operator selecting component further causing the device to:
identify specialized query operators handling at least two query tasks specified in at least two query terms of the query; and
upon identifying a specialized query operator, select the specialized query operator for the at least two query terms of the query.
7. The system of claim 1 , at least one specialization criterion of a specialized query operator specifying at least one data type involved in the query task.
8. The system of claim 7 , the query operator set comprising:
a first specialized query operator specifying a query task involving a first data type, and
a second specialized query operator specifying the query task involving a second data type that is more specific than the first data type of the first specialized query operator.
9. The system of claim 7 , the at least one specialized query operator specifying a query task comprising a data set typecasting with respect to a data type.
10. The system of claim 9 , the query task applying to the data set comprising objects of the data type.
11. The system of claim 7 , the query task based on at least one data type property of the data set.
12. The system of claim 1 , comprising:
a data store targeted by the query, and
a query applying component configured to apply the query processing solution to the data store.
13. The system of claim 1 , at least one query operator generated by at least one data type of a data set involved in the query.
14. The system of claim 1 , wherein at least one multiple-task query operator is configured to perform at least one additional query task on the data set before performing the query task on the data set.
15. The system of claim 1 , wherein at least one multiple-task query operator is configured to perform at least one additional query task on the data set upon completing the query task on the data set.
16. The system of claim 1 , wherein at least one multiple-task query operator is configured to perform at least one additional query task on the data set while concurrently performing the query task on the data set.
17. The system of claim 1 , wherein at least one multiple-task query operator is configured to perform at least one additional query task on the data set upon failing to complete the query task on the data set.
18. The system of claim 1 :
at least one additional query task of the multiple-task query operator specified by a second query term of the query; and
the instructions of the query operator selecting component further causing the device to select the multiple-task query operator for the query term and the second query term.
19. A method of generating a query processing solution for a query from a query operator set comprising at least one query operator configured to perform at least one query task on a data set, the method comprising:
for respective query terms:
for respective multiple-task query operators respectively configured to perform the query task and at least one additional query task on the data set:
determining whether the at least one additional query task of the multiple-task query operator is also to be performed on the data set, and
upon determining that the additional query task is also to be performed on the data set, selecting the multiple-task query operator for applying the query task and the at least one additional query task to the data set; and
upon failing to select a multiple-task query operator for the query term, selecting a single-task query operator for applying the query task to the data set; and
generating the query processing solution as a sequence of selected query term operators.
20. A nonvolatile computer-readable storage device comprising instructions that, when executed on a processor of a device, cause the device to generate a query processing solution for a query from a query operator set comprising at least one query operator configured to perform at least one query task on a data set, by:
for respective query terms:
for respective multiple-task query operators respectively configured to perform the query task and at least one additional query task on the data set:
determine whether the at least one additional query task of the multiple-task query operator is also to be performed on the data set, and
upon determining that the additional query task is also to be performed on the data set, selecting the multiple-task query operator for applying the query task and the at least one additional query task to the data set; and
upon failing to select a multiple-task query operator for the query term, selecting a single-task query operator applying the query task to the data set; and
generating the query processing solution as a sequence of selected query term operators.