For general tips on speed improvement, please read the relevant section in our AskiaAnalyse FAQ article.
For additional info on how this can now be done through AskiaAnalyse for QEW and QES files, please read this section of our What's new in AskiaAnalyse 5.4 article.
We know that inverting your data in Analyse will create a .DAT folder in the same directory as your QES or QEW and store your data in such a way that it is read faster by Analyse.
Analyse reads the data in conjunction with the question information in the QES file.
For a stand alone data-set where the file is a single QES, this is fine.
However, for complicated Surf set-ups when you have a large number of QES (wave) files, we can begin to see a reduction in speed because the question information in all these QES files needs to be accessed repeatedly from different databases. Opening and closing these tables in the QES back-end starts to become a cumbersome process when there are many.
To combat this there is a feature in AskiaSurf which can help when your AskiaSurf set-ups get to this point. The 'Improve Metadata Speed' option can be found in the Edit menu of Surf.
The first thing to do is ensure your QEW is inverted i.e. when your QEW is open in AskiaAnalyse you see the INV sign in the bottom right-hand corner of AskiaAnalyse:
The folder should have .DAT folders for all of the individual QES files and the QEW:
You can then open the QEW file up in AskiaSurf and go to Edit > Improve Metadata Speed:
What does this do?
It opens all the source files in the QEW and for each of them, removes screens, routings, screen groups, question classes, resources, versions, languages, revisions and all captions. They're then saved to a QEX file with "-meta" and the end of the file name.
These can now be used along with all the .DAT folders and the QEW to access the data in Analyse - No need for the QES files anymore.
Why does this improve speed?
The way the required question information is stored in the QEX file is quicker to access than it is in a QES file. The observed speed improvement is more noticeable if you are using 64 bit Analyse.
Using the QEW from the folder in the screenshot above allows you to access the data in AskiaAnalyse in exactly the same way as before with the added benefit of seeing an improvement in speed for large set-ups.
A key point is that you can take advantage of this functionality in AskiaSurf set-ups that are placed on AskiaVista. You will need AskiaVista versions 184.108.40.206 and higher (using AskiaAPI.dll 14.11.2017 onward).