[Geoserver-users] Question about GEOS-9757

[Kalesse S. <Soe...@dw...>]

Hi, 

we have a question regarding the fix for https://osgeo-org.atlassian.net/browse/GEOS-9757. We are indeed happy about this functionality, but we noticed an inconvenience. 

We observed that the validation code for vector dimensions creates a filter for the particular dimension but wraps it using a ALL_NAMES query, which basically results in a query for all features attributes. This behavior could result in a lot of feature data to be transferred from the backends to GeoServer (probably depending on the store implementation). 

On the other hand when querying the data stores for capabilities, the queries used there are limited the particular dimension attribute. This results in much less data to be transferred from the backends, especially if the result is only used to check if it's not empty. 

The question would be if the validation code could be improved in such a way that it functions similar to the way dimension data for capabilities is queried - wrap the filter in a query, but fix the query property to be the particular dimension attribute. The org.geoserver.wms.WMS#validateTimes() method for example could be adjusted in a way as depicted below (and similarly for the validation methods for elevation and custom dimensions):

private void validateTimes(....
...
      Query timeQuery =
                    getDimensionQuery(
                            getTimeFilter(explicitTimes, typeInfo, builder),
                            timeInfo,
                            typeInfo.getFeatureType().getName().getLocalPart());
            if (DataUtilities.first(fs.getFeatures(timeQuery)) == null) {
                throwInvalidDimensionValue(request, ResourceInfo.TIME, ResourceInfo.TIME);
            }
...
}

    /**
     * wraps the given filter in a query for dimension requests.
     *
     * @param filter the filter
     * @param dimensionInfo the dimension info
     * @param typeName the feature type name
     * @return a query that wraps the filter and restricts the query to the dimension attribute
     */
    private static Query getDimensionQuery(Filter filter, DimensionInfo dimensionInfo, String typeName) {
        final Query dimQuery = new Query(typeName, filter);
        List<String> propertyNames = new ArrayList<>();
        propertyNames.add(dimensionInfo.getAttribute());
        if (dimensionInfo.getEndAttribute() != null && dimensionInfo.getPresentation() != DimensionPresentation.LIST) {
            propertyNames.add(dimensionInfo.getEndAttribute());
        }
        dimQuery.setPropertyNames(propertyNames);
        return dimQuery;
    }

Thanks for the help 
Best Regards

Sören