- Partial load (for dealing with large files)
- Pre-calculated statistical data (various counts for each field and each unique value)
- Query tool for calculating simple aggregates (counts, sum, avg)
They make QViewer not simply a file viewer, but actually a data profiling tool which should help find data anomalies (unexpected nulls, text instead of numbers, duplicate rows, etc.) faster. I tried to automate some frequent analysis operations which usually require some time & effort when using regular QlikView. For instance, besides viewing QVD row-level data, with QViewer you can do a little bit faster the following:
- Search a field for nulls
- Filter values by type (text/number)
- Count unique values
- Count occurrences of each unique value
- See immediately type of value (numeric/text/null)
These operations are pretty basic and make no problem for regular QlikView developer, but they take time because of their frequency. If QViewer can save you 15 minutes a day, it saves you 65 hours of working time a year (or more than 8 full working days). Multiply this number by your hourly rate and see the benefit in cash equivalence :)
Digging QVD format was an interesting exercise -- since it's a native QlikView format it gives some understanding how QlikView works under the hood, from what it started and how it has evolved into what we know today. I now understand better technical challenges with which QlikTech's developers faced and I have to admit that they've done excellent job resolving them. Exceptional QlikView's performance, which we know, is result of smart optimization and hard work. Also it looks like there was a portion of luck as some QlikView's key features were not designed as those from the beginning, but were result of evolution.
What's next for QViewer? As of today, I've implemented all essential features which I planned to make it useful for daily work. It will be remaining free until end of this year. Before end of this year a paid version to be introduced along with free limited version.
There still are some things to do, mainly because QViewer still doesn't perform as I want it to on large files due to limitations of standard .NET control (specifically DataGridView). I'm thinking about writing own custom control to replace it but this task may be very time-consuming. It would also be interesting to implement partial load with WHERE condition, as well as make Query a bit more advanced and, for instance, make it support conditions like where field is null.
I would appreciate to hear your ideas -- how to make QViewer better for your daily work. Please, leave your comments here. Thanks.