QUERYING ACROSS DISPARATE SCHEMAS
Efficient querying across disparate schemas can be implemented by initially limiting the total number of lists and the total number of items queried and by using a mechanism for aligning data during the query. Querying across disparate data (e.g., data that is stored in accordance with disparate schemas) can comprise removing lists that are not applicable, defining a data alignment for the lists being searched, and executing the query.
1 . A computer-implemented method for querying data stored in accordance with disparate schema, comprising:
evaluating a search query to determine which lists in the stored data comprise fields that are implicated by search terms in the search query;
defining a data alignment table in response to the evaluation wherein the data alignment table comprises entries for the implicated lists, wherein each entry is associated with a list name and a field of the named list; and
using the entries of the data alignment table to execute the query.
2 . The method of claim 1 wherein the stored data is stored in a sparse data table format.
3 . The method of claim 1 wherein the stored data is stored in a compact data table format.
4 . The method of claim 1 wherein the entry association is a link to a column of data entries in a list.
5 . The method of claim 1 further comprising sorting the entries of the data alignment table.
6 . The method of claim 5 wherein the sorting comprises sorting in accordance with field data.
7 . The method of claim 5 wherein the sorting comprises sorting in accordance with the list names.
8 . The method of claim 5 wherein the sorting comprises sorting in accordance with field data and sorting in accordance with the list names.
9 . The method of claim 1 wherein the alignment table excludes lists that do not have fields specified in the query.
10 . The method of claim 1 further comprising executing a second query using entries of the data alignment table.
11 . The method of claim 1 further comprising executing a second query using a second data alignment table.
12 . The method of claim 11 further comprising logically combining the results of the query and the second query.
13 . The method of claim 1 wherein the stored data is stored in columns wherein at least one of the columns stores data of the same type from different lists.
14 . A system for querying data stored in accordance with disparate schema, comprising:
a user interface for receiving a user query for search for data in a structure having multiple lists, wherein each list has an arbitrary schema for defining fields that are associated with each list;
a data structure evaluator for determining data dependencies in the structure a query parser for determining lists that are implicated by a query and by the determined data dependencies;
a data alignment table constructor for constructing an alignment table that comprises entries for the implicated lists, wherein each entry is associated with a list name and a field of the named list; and
a query execution unit for using entries from the data alignment table to execute queries.
15 . The system of claim 14 wherein the stored data is stored in columns wherein at least one of the columns stores data of the same type from different lists.
16 . The system of claim 14 wherein the query identifies the columns to be searched.
17 . The system of claim 16 wherein the query identifies the lists to be searched.
18 . A tangible computer readable medium comprising instructions for querying data stored in accordance with disparate schema, comprising:
displaying a user interface for displaying the disparate schema and for receiving a search query from a user formed in response to the displayed disparate schema;
evaluating the search query to determine which lists in the stored data comprise fields that are implicated by search terms in the search query;
defining a data alignment table in response to the evaluation wherein the data alignment table comprises entries for the implicated lists, wherein each entry is associated with a list name and a field of the named list; and
using the entries of the data alignment table to execute the query.
19 . The method of claim 18 further comprising instructions for displaying results on the user interface wherein a representation for empty data is displayed to represent missing fields.
20 . The method of claim 18 further comprising instructions for logically combining the results of the search query and a second query.