  The IVOA Provenance Data model defines entities, agents and activities as
container classes to describe the provenance of datasets, with the executed
tasks and responsibilities attached to agents. It also provides a set of
classes to describe the activities type and their configuration template, as
well as the configuration applied effectively during the execution of a task.
Here we highlight lessons learned in the implementation of the CDS ProvHiPS
service distributing provenance metadata for the HST HiPS data collections, and
for the HST archive original images used to produce the HiPS tiles. ProvHiPS is
based on the ProvTAP protocol, the emerging TAP standard for distributing
provenance metadata. ProvTAP queries may rapidly become very complex. Various
graph representation strategies, including ad hoc solutions, triplestore and
SQL CTE have been considered and are discussed shortly.
