Databases Reference
In-Depth Information
The
0.Includes
folder is used to store re-usable code that is called from the end
documents via an
Include
statement. The
1.Source Data
folder represents the
Source Layer; this folder is used because our source database is composed of CSV
files but wouldn't be required otherwise. The
2.Workbooks
folder holds all QVD
Generators (QVW files) for both the Base Layer and the Transformation Layer. The
3.QVD
folder is used to store the resulting QVD files from both the Base Layer
(using the
Source
subfolder) and the Transformation Layer (using the
Transformed
subfolder). The
4.Applications
folder represents the Presentation Layer.
Inside these folders, you will find all source tables in CSV format, as well as the
extract QVWs and the base QVDs used in previous chapters. We will work directly
with the Transformation Layer in the coming sections.
Loading data already stored in QlikView
The first lesson in advanced data transformation will be about optimizing loads when
processing data. If you remember from
Chapter 3
,
Data Sources
, we discussed the
various ways in which we can pull data from different sources into QlikView. We also
described how we can take advantage of the QVD file format to store and read data in
super-fast mode. Now, we will describe yet another way of reading source tables, but
this time the "source" will be QlikView itself. There are different cases in which this
approach will prove useful and we will describe two scenarios to perform it:
• Accessing data already stored in a QlikView data model (QVW file) from a
separate QlikView document. We will call this approach
Cloning a QlikView
data model
.
• Accessing data from the same QlikView document in which the data model
resides. We will call this approach
Loading from RAM
.
Cloning a QlikView data model
This concept refers to the ability of replicating the data model of an already created
QlikView document and placing it into another QlikView document without
accessing the original data source. In technical terms, it's a
Binary load
. Once the
data model is cloned by the second QlikView document, it can be manipulated
further, integrated into a bigger data model (that is, adding more tables to it), or even
reduced by removing some of its tables or data.
