topic Re: Creating QVD's in QlikView

Creating QVD's

Thu, 31 Oct 2013 16:33:16 GMT

Hi would anyone know how to create a QVD and what i need to do? any sources that can help me?

Regards

Re: Creating QVD's

swuehl — Thu, 31 Oct 2013 16:39:23 GMT

Well, first place I would look into would be the Help file or reference manual.

From the Help:

QVD Files

A QVD (QlikView Data) file is a file containing a table of data exported from QlikView. QVD is a native QlikView format and can only be written to and read by QlikView. The file format is optimized for speed when reading data from a QlikView script but it is still very compact. Reading data from a QVD file is typically 10-100 times faster than reading from other data sources.

QVD files can be read in two modes: standard (fast) and optimized (faster). The selected mode is determined automatically by the QlikView script engine. Optimized mode can be utilized only when all loaded fields are read without any transformations (formulas acting upon the fields), though the renaming of fields is allowed. A WHERE clause causing QlikView to unpack the records will also disable the optimized load.

A QVD file holds exactly one data table and consists of three parts:

A well formed XML header (in UTF-8 char set) describing the fields in the table, the layout of the subsequent information and some other meta-data.
Symbol tables in a byte stuffed format.
Actual table data in a bit-stuffed format.

Purpose of QVD Files

QVD files can be used for many purposes. At least four major uses can be easily identified. More than one may apply in any given situation:

Increasing Load Speed

By buffering non-changing or slowly changing blocks of input data in QVD files, script execution becomes considerably faster for large data sets.

Decreasing Load on Database Servers

The amount of data fetched from external data sources can also be greatly reduced. This reduces work load on external databases and network traffic. Furthermore, when several QlikView scripts share the same data it is only necessary to load it once from the source database into a QVD file. The other applications can make use of the same data via this QVD file.

Consolidating Data from Multiple QlikView Applications

With the Binary script statement it is possible to load data from only one single QlikView application into another one, but with QVD files a QlikView script can combine data from any number of QlikView applications. This opens up possibilities e.g. for applications consolidating similar data from different business units etc.

Incremental Load

In many common cases the QVD functionality can be used for facilitating incremental load, i.e. exclusively loading new records from a growing database.

To learn more about the use of QVD files and Incremental Load, follow the link below:

Using QVD Files for Incremental Load

Create QVD Files

A QVD file can be created by one of three different methods:

Explicit creation and naming using the Store command in the QlikView script. Simply state in the script that a previously read table or part thereof is to be exported to an explicitly named file at a location of your choice.
Automatic creation and maintenance from script. By preceding a load or select statement with the Buffer prefix, QlikView will automatically create a QVD file which under certain conditions can be used instead of the original data source when reloading data.
Explicit, manual creation and naming from layout or via Internal Macro Interpreter. Data can be exported from the QlikView layout via GUI commands or Automation macros. In the GUI you will find QVD as one of the possible export formats under the Export... command, found on the object menu of most sheet objects.

There is no difference between the resulting QVD files, e.g. with regard to reading speed etc.

Reading Data from QVD Files

A QVD file can be read into or accessed by QlikView by the following methods:

Loading a QVD file as an explicit data source. QVD files can be referenced by a load statement in the QlikView script just like any other type of text files (csv, fix, dif, biff etc). The File Wizard: Type handles QVD files by the same principles.
Examples:
load * from xyz.qvd (qvd);
load Name, RegNo from xyz.qvd (qvd);
load Name as a, RegNo as b from xyz.qvd (qvd);
Automatic loading of buffered QVD files. When using the Buffer prefix on load or select statements, no explicit statements for reading are necessary. QlikView will determine the extent to which it will use data from the QVD file as opposed to acquiring data via the original load or select statement.
Accessing QVD files via the script. A number of script functions (all beginning with qvd) can be used for retrieving various information on the data found in the XML header of a QVD file. These functions are presented under the File Functions in Script functions.

QlikView 11.20 SR3, 12018

Re: Creating QVD's

Thu, 31 Oct 2013 16:47:30 GMT

Creating QVDs and Using the Store Function - YouTube

Re: Creating QVD's

Fri, 01 Nov 2013 09:14:36 GMT

thanks

Re: Creating QVD's

Fri, 01 Nov 2013 09:22:30 GMT

supposed that your table name is Table1, you just need to write the following script after your table load statement:

Store Table1 into Table1.qvd (qvd);

This will store the QVD in the same folder where you have saved the qvw.

You can also be more specific to where you want to save the qvd, for example:

Store Table 1 into C:\......\Table1.qvd (qvd);

Good luck!

Re: Creating QVD's

rustyfishbones — Fri, 01 Nov 2013 09:29:52 GMT

Check these out on Youtube

Qlikview Create a QVD by RFB 144 - YouTube

and

Qlikview QVD Variable Name by RFB 145 - YouTube

Re: Creating QVD's

Fri, 01 Nov 2013 09:35:36 GMT

Hi,

You can create QVD at different stages of your process. It could be right after you import data from an external source and store it as QVD format for QlikView's faster access and processes OR export as a ready-to-use table after applying some formatting, groupings or even calculations for your other QVW applications to access to and read. Or, you may simply export for archive purposes. Do not forget that QVD is a flat table - that's it.

Please see dna's reply to your question which shall become handy for you. If you still need help, let us know.

Best wishes,

Re: Creating QVD's

ngulliver — Wed, 20 Nov 2013 11:24:22 GMT

Hi, Tyrone.

There is a useful link on QVDs for those not used to using them:

http://www.quickintelligence.co.uk/qlikview-qvd-files/

Regards,

Neil

Re: Creating QVD's

Sat, 12 Apr 2014 10:40:24 GMT

Hi Alan,

Could you please help on how to modify the month into numerical format?

So instead of 2013Jul, I would need 201307.

Thanks in advance,

Joni

Re: Creating QVD's

rustyfishbones — Sat, 12 Apr 2014 14:34:27 GMT

Change the format of the Date

so you may have it as YYYYMMM

Change it to

YYYYMM

if that does not help try sharing your App

Regards

Alan

Re: Creating QVD's

Mon, 14 Apr 2014 08:27:03 GMT

Hi Alan,

Thanks for your assistance.

I used this method and it works:

LET i=Date(ReloadTime(),'YYYYMMDD');

Best Regards,

Joni

Re: Creating QVD's

Anonymous — Tue, 17 Mar 2015 21:27:24 GMT

First learn a object Language (Java,C#,C++)...

Second study use of Hash Maps (ex MapDB in java)