Query metadata engine
In one example, a method comprises receiving, with a data access service, an input query from an enterprise software application, wherein the data access service is positioned between the enterprise software application and a multidimensional data source; parsing the input query into a parse tree; generating an abstract syntax tree based on the parse tree, the abstract syntax tree comprising input query elements and multidimensional expression query elements based on the input query; performing an evaluation of metadata comprised in the multidimensional expression query elements of the abstract syntax tree; restructuring the abstract syntax tree based on the evaluation of the metadata; executing a query based on the restructured abstract syntax tree on the multidimensional data source; and retrieving a query result set from the multidimensional data source comprising results that are responsive to the query based on the restructured abstract syntax tree.
1. A method, comprising:
receiving, with a data access service, an input query from an enterprise software application, wherein the data access service is positioned between the enterprise software application and a multidimensional data source;
parsing the input query into a parse tree;
generating an abstract syntax tree based on the parse tree, the abstract syntax tree comprising input query elements and multidimensional expression query elements based on the input query;
performing an evaluation of metadata comprised in the multidimensional expression query elements of the abstract syntax tree;
restructuring the abstract syntax tree based on the evaluation of the metadata;
executing a query based on the restructured abstract syntax tree on the multidimensional data source; and
retrieving a query result set from the multidimensional data source comprising results that are responsive to the restructured abstract syntax tree.
2. The method of claim 1 , wherein generating the abstract syntax tree based on the parse tree comprises populating the abstract syntax tree with functions, operators, and metadata object information for identifiers from the parse tree.
3. The method of claim 1 , wherein performing the evaluation of metadata comprised in the multidimensional expression query elements of the abstract syntax tree comprises retrieving metadata information from the multidimensional data source using an OLAP schema rowset interface.
4. The method of claim 1 , wherein performing the evaluation of metadata comprised in the multidimensional expression query elements of the abstract syntax tree comprises executing a request on a node of the abstract syntax tree and evaluating what is returned by the node.
5. The method of claim 1 , wherein performing the evaluation of metadata comprised in the multidimensional expression query elements of the abstract syntax tree comprises executing a request on a node of the abstract syntax tree and evaluating what provides context to the node.
6. The method of claim 1 , wherein performing the evaluation of metadata comprised in the multidimensional expression query elements of the abstract syntax tree comprises evaluating an order of solve order equations that provide context to value expressions in the abstract syntax tree.
7. The method of claim 1 , wherein performing the evaluation of metadata comprised in the multidimensional expression query elements of the abstract syntax tree comprises evaluating one or more expressions in the abstract syntax tree to determine what hierarchies provide context to one or more functions that correspond to the one or more expressions.
8. The method of claim 1 , wherein performing the evaluation of metadata comprised in the multidimensional expression query elements of the abstract syntax tree comprises executing a multidimensional expression query on the metadata comprised in the multidimensional expression query elements of the abstract syntax tree, and thereby evaluating metadata that provides context to functions specified by the input query.
9. The method of claim 1 , wherein performing the evaluation of metadata comprised in the multidimensional expression query elements of the abstract syntax tree comprises collecting levels that are in context with each of one or more value expressions in the input query.
10. The method of claim 1 , wherein restructuring the abstract syntax tree based on the evaluation of the metadata comprises evaluating what members in the input query will need a value in the query result set.
11. The method of claim 1 , wherein performing the evaluation of metadata comprised in the multidimensional expression query elements of the abstract syntax tree comprises determining what levels will be in the query result set.
12. The method of claim 11 , wherein restructuring the abstract syntax tree based on the evaluation of the metadata comprises mapping members in the input query to the levels in the query result set.
13. The method of claim 1 , further comprising performing post-processing operations on the query result set.
14. The method of claim 1 , further comprising rendering the query result set in accordance with a report layout to produce a finalized report output.
15. The method of claim 1 , wherein the input query conforms to Multidimensional Expression query language (MDX).