Hey. I need to use a specific function provided by Postgres - string_agg.
I thought it would be enough to supplement the corresponding arp-module, but that was naive on my part If I add a description of a new function to the arp module, and then try to call it, I get an error:
org.apache.calcite.sql.validate.SqlValidatorException) No match found for function signature STRING_AGG(, )
As far as I can understand, this is due to the fact that dremo uses calcite to parse and optimize queries. In turn, calcite only supports basic sql functions (they have an enumeration of them).
Is there some way to add support for a custom sql function at the dremo level on my own, or will I have to delve into the sources of calcite, etc.?
Do I understand correctly that arp allows you to write adapters that implement only the basic SCL functions (listed in the documentation) and do not imply their declarative extension?