Filtering on xsd:dateTime drops boundary values when using timezone-aware data

[zumbov2]

Disclaimer: I’m not entirely sure whether this is a bug or just my misunderstanding of xsd:dateTime handling.

Describe the bug

When filtering cubes with xsd:dateTime dimensions in Visualize, observations at the lower boundary of a filter range can disappear if the underlying data contains timezone-aware values (e.g. Z).

It appears that during filter generation, Visualize converts these values to local time (e.g. UTC -> CET/CEST), while the SPARQL query compares them against timezone-less literals. This leads to inconsistent comparisons and causes some observations (typically boundary cases) to be excluded.

Steps to Reproduce

• Use a cube with a dateTime dimension where values are stored with timezone
• Open the cube in Visualize
• Select "Table" as your chart type
• Apply a filter on the dateTime dimension
• Inspect the generated SPARQL query.

FILTER (
    (?dimension5 >= "2003-01-14T01:00:00"^^<http://www.w3.org/2001/XMLSchema#dateTime>)
  )
  FILTER (
    (?dimension5 <= "2015-04-24T02:00:00"^^<http://www.w3.org/2001/XMLSchema#dateTime>)
  )

Expected behavior

Filtering should be consistent with the underlying data semantics.

In particular, values representing the same instant (e.g. 2003-01-14T00:00:00Z and 2003-01-14T01:00:00 in CET) should not lead to observations being excluded due to timezone handling differences. Boundary values should remain included.

Screenshots or video

output2.mp4

Environment

• TEST v6.4.0

[BenjaminHofstetter]

@zumbov2 This is a bug, and thanks for looking into it!