Looks like the function get_actual_variable_range() was written with the knowledge that virtual/hypothetical indexes may exist, but the assumption seems wrong.
One one hand get_actual_variable_range() expects that virtual indexes do not have an OID assigned, on the other hand explain_get_index_name_hook() is handed just an index's OID to get its name back; IMHO these are based on two conflicting assumptions about whether a virtual index will have an OID assigned.
Attached patch fix_get_actual_variable_range.patch tries to fix this by introducing a new hook that can help Postgres decide if an index is fictitious or not.
Also attached is the patch expose_IndexSupportInitialize.patch, that makes the static function IndexSupportInitialize() global so that the Index Advisor doesn't have to reinvent the wheel to prepare an index structure with opfamilies and opclasses.
Regards,
--
gurjeet.singh
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