Virtual table index mechanism and method for multi-attribute compound condition query
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Abstract
A virtual table index mechanism and a method for a multi-attribute compound condition query relate to a field of computer application technology. The virtual table index mechanism for a multi-attribute compound condition query includes: an index manager; a condition analyzer; and a pre-execution engine. The present invention forms index key values corresponding to a plurality of attributes in a virtual table. When querying, a query condition for the virtual table is calculated. Referring to a key value index, whether a mapping physical table of the virtual table should be executed is independently pre judged according to the attributes, so as to ensure that query is applied only to a virtual sub-table satisfying a corresponding key value condition. The present invention is effective for multi-attribute compound condition query, and is suitable for indexing virtual tables.
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Citations
25 Claims
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1-8. -8. (canceled)
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9. A virtual table index mechanism for a multi-attribute compound condition query, comprising:
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an index manager; a condition analyzer; and a pre-execution engine; wherein the index manager manages index key values of attributes of a virtual table, and supports a management of a single key value and an interval key value of the multiple attributes of the virtual table; the condition analyzer disassembles a query condition applied to the virtual table and analyzes a predicate;
the condition analyzer sequentially analyzes the whole query condition for every indexed attribute according to an SQL (Structure Query Language) grammar, and, after masking a predicate expression of other attributes with a true value, only maintains the predicate condition of the indexed attribute for judging whether an index of the indexed attribute satisfies the query condition;
meanwhile, if the index key value of the attribute is an interval value, the analyzer further calculates whether the predicate of the attribute in the query condition masked with the true value is true or false according to the interval value, and replaces the predicate with a Boolean result (true/false);
if the predicate is not able to be calculated, an inferred result needing querying the virtual table is directly returned and displayed;the pre-execution engine judges whether the query condition partially replaced by a true value expression and the Boolean result is true or false according to the index key value of the corresponding attribute, and determines whether the index of the corresponding attribute satisfies the query condition;
if the query condition is not satisfied, an inferred result not querying the virtual table is directly returned;
if the query condition is satisfied, an index of other the attributes is judged;
in some cases, an execution condition is satisfied by default;
if the index key value is the interval value, only a beginning value and an ending value are utilized.
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10. A virtual table index method for a multi-attribute compound condition query, comprising steps of:
forming index key values corresponding to a plurality of attributes in a virtual table;
when querying, calculating a query condition applied to the virtual table;
referring to a key value index, independently pre judging whether a mapping physical table of the virtual table should be executed for each of the attributes, so as to ensure that query is applied only to a virtual sub-table satisfying a corresponding key value condition.- View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
Specification