If the dataset in a database is large, it is possible to load aggregated query results into QlikView without loading the complete dataset into the QlikView data model using the Direct Discovery function.
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QlikView determines which data resides in-memory and which data is direct discovery data by
using the special script syntax, “DIRECT SELECT”. This syntax allows certain data elements not to
be loaded into the QlikView data model during the script reload process, but still available for
query purposes from the QlikView User Interface and to be combined for analysis with the
QlikView in memory dataset.
Once the direct discovery structure is established, the direct discovery fields can be used with
certain QlikView objects. When a direct discovery field is used on the QlikView object, QlikView
will automatically create the appropriate SQL query to run on the external data source. The
result of the query will be displayed on the QlikView object. When selections are made on the
QlikView application, the associated data values of the direct discovery fields will be used in the
WHERE conditions of the queries. With each selection, the direct discovery charts will be
calculated, where the calculations and aggregations will be done on the source table by
executing the SQL query created by QlikView. It is possible to use calculation condition feature of
the QlikView charts to set a condition indicating when the chart should be calculated. Until that
condition is met, QlikView will not run queries and the chart will not be calculated. Please note
that QlikView will execute SQL queries on the data source for some of the list boxes that use
direct discovery fields. This is required to achieve the associative navigation capability.
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DIRECT QUERY DIMENSION fieldlist [MEASURE fieldlist] [DETAIL fieldlist] ] [DETACH fieldlist]FROM tablelist
Note 1: The DIMENSION, MEASURE, and DETAIL keywords can be used in any order.
Note 2: The DIMENSION and FROM keyword clauses are required on all DIRECT QUERY statements. The FROM keyword must appear before the DIMENSION keyword.
Note 3: The DIRECT QUERY statement cannot contain DISTINCT or GROUP BY clauses.
could be changed to the following DIRECT QUERY statement:
Note 4: DIRECT QUERY statements are written directly in the Edit Script dialog box. They are not generated with the Create Select Statement.
Reference: QlikView Help