Database Viewer

Introduction

figure 1: the GUI of the Database Viewer

The database viewer is a configuration support tool for inspecting the contents of the FEWS database (localdatastore). It provides an overview in tabular form of statistics and other metadata (columns) of the timeseries (rows) in the database. To aid the inspection of data, the user can add or remove columns, and select and filter rows. From the Database Viewer it is also possible to access the content (=values) of selected timeseries by opening the timeseries dialog. The database viewer is available in two different modes:

• Workflow based database viewer - for each available workflow, all timeseries written to the database in that workflow can be inspected. From the Explorer, the Database Viewer can be accessed using <F12> + J.
• Timeseries lister - for the selection made in the Data Viewer or Forecasts (Explorer Tabs) all available timeseries in the database are listed and can be inspected. To enable this mode, some configuration is required.

Configuration (mode: timeseries lister)

To enable the timeseries lister, it must be added as explorertask in Explorer.xml:

<explorerTask name="Timeseries Lister">
   <iconFile>tableInfo.jpg</iconFile>
   <taskClass>nl.wldelft.fews.gui.plugin.timeseriestableviewer.TimeSeriesTableViewer</taskClass>
   <toolbarTask>true</toolbarTask>
   <menubarTask>true</menubarTask>
   <allowMultipleInstances>false</allowMultipleInstances>
   <accelerator>ctrl T</accelerator>
</explorerTask>

Usage

The database viewer enables the user to inspect the database. The database records are visualised as individual rows, which can be selected. When selected it can be browsed through (all columns) or its values can be inspected through a graph (scalar series) or the spatial display (grid data). 

In the top window, workflows are available. When selected, the lower part of the screen shows the records which have been written to the database in this selected workflow. In this lower part, individual rows can be selected as well.

All meta information and statistics are calculated on-the-fly and are not stored. Within selections or filters (e.g. on start/end time) the content of the (visible) columns are updated immediately. 

There are many columns which can be viewed: general columns about module instance, location, parameter, disk space and all kind of relevant meta information about the selected record(s).

Besides the 'general' metadata, the basic statistics of that row can be inspected. These basic statistics are sum, average, maximum, minimum, etc. 

The remaining columns describe the quality of the data. If the user e.g. wants to know how many values are 'unreliable' and how many 'periods' of unreliable data are available, this information can be retrieved. The same is true for all kinds of combinations of doubtful, completed and corrected data. This same functionality (number of records, periods) is available for primary and secondary validation results. This means that the user can inspect number of records and periods of e.g. hard maximums and flag comparison or series comparison. 

When many records (rows) are available the user can filter the results. Double-clicking a cell will automatically filter for that value. If you want to filter on e.g. a location, select the location (name or Id) column and press F8 or double-click it. The background color of the cell will turn blue (meaning there's a filter on it). 

This filter mechanism is applicable on all available columns, including the Start and End Time. When the users changes the start and/or end time, the visible columns will be updated accordingly.

Two types of filters - with or without data hierarchy

Note well that there are two modes for using the Database Viewer. When using the filters on the top of the screen of the database viewer, the timeseries can be viewed as they are available in the database. However, when using the other filters from for instance FEWS-Explorer (left below), the database viewer shows the timeseries as they are in the data hierarchy. In the first case this means that external data with a scenario can be made visible, and in the latter case, the external timeseries are viewed as they were imported, i.e. without the scenario applied. For more info read about the fews data hierarchy.

Context Menu Options

figure 2: context menu of the Database Viewer

The Graphical User Interface contains a number of context menu options for selection/filtering and inspection of data. Right-click the mouse on one of the cells to access the context menu.

Special Filter option: Start time / End time

Two columns have special features: The Start and End time columns can be used to increase or limit the view period. If you adjust these all statistical columns or columns showing information about quality flags and (secondary) validation will be adjusted automatically.

Doubleclicking in these time columns will provide the user with the following, see figure below.

figure 3: Special filter in the Start/End time columns

Meta Data Elements / Select Columns (F8)

figure 4: Selecting different columns (elements) in the Database Viewer

The meta data elements are grouped as follows.

• General (e.g. moduleinstanceId, location, parameter, timestep, blobsize etc.)
• Basis Statistics (Sum, Mean, Median, Standard Deviation, Percentile-5, Percentile-95)

The below mentioned groups give an overview of number of values and periods based on quality flags, primary and secondary validation.

• Missing
• Original Reliable
• Corrected Reliable
• Completed Reliable
• Original Doubtful
• Corrected Doubtful
• Completed Doubtful
• Original Unreliable
• Corrected Unreliable
• Completed Unreliable
• Soft Min
• Soft Max
• Hard Min
• Hard Max
• Same Reading
• Rate of Change
• Temporary shift
• Series Comparison
• Flag Comparison
• Spatial Homogeneity

The list of available columns can be adjusted by (un)selecting the individual elements. Only the selected ones will be visible in Database Viewer after confirming by clicking <OK>.

Selections can be copied to the clipboard (<Copy Selection> button) and adjusted in a text editor (figure 5). These lists can be shared amongst users (e.g. e-mail). From a text editor you can adjust the list by removing rows, select the remaining rows and then copy it the clipboard (<CTRL+C>) again. After that use the <Paste Selection> button to update your selected columns (figure 6). See below:

figure 5: Copying the selection of columns to clipboard

figure 6: Pasting the selection of columns from the clipboard

Delete module instance from Database Viewer

From build 2016.02 it is possible to remove module instances from Local Data Store via Database Viewer. This function only exists in FEWS stand alone mode. The procedure is as follows:    

1. In Database Viewer, select one workflow, press F12, a menu will pop out (figure 7).

figure 7: F12 menu in Database Viewer

2. Select '9 Delete module instance for selection', the module instances in this workflow will be displayed for selection. One can select the module instances that should be removed from the database.

figure 8: select module instances to be removed from database

3. Press 'OK', the selected module instances will be removed. If all module instances in one workflow are all removed, the workflow will become empty, but the workflow still appears in the Database Viewer.

To completely remove this workflow from the list, go to FEWS F12 menu (in log panel, press F12), select 'P database', select 'validate, repair, and compact datastore indices and cache files', then restart FEWS, the workflow will be completely removed. To completely remove the data from the localDataStore (i.e. reduce file size), press F12, select 'P database,' and select 'repair and defrag localdatastore'.

figure 9: Remove workflow and data using F12 - P - database menu