BUG #15608: Index is used for an inherit table but not for the table with the index

The following bug has been logged on the website:

Bug reference:      15608
Logged by:          Axel Hörteborn
Email address:      axel.n.c.andersson@gmail.com
PostgreSQL version: 11.1
Operating system:   Windows 10 x64
Description:

I tried to ask a question on Stackoverflow but it seems to be a bug:
Hopefully is all the details required in the Stackoverflow question, in
short I have a "table_2017_1" which Inherits "table_2017", so no data or
index are stored directly in "table_2017". When I run a question on
table_2017 it uses the index on table_2017_1 but when I run the exact same
question on "table_2017_1" it doesn't evaluate the index and perform a
sequence scan instead. 


https://stackoverflow.com/questions/54362324/postgresql-index-is-used-for-an-inherit-table-but-not-for-the-table-with-the-i