Primary Key Constraint on inheritance table not getting route to child tables

ALTER TABLE ADD Constraints PRIMARY KEY on inheritance table not getting route to child table.

But when we do ALTER TABLE DROP Constraint on the same, it complains about constraint does not

exists on child table.

Consider the following example

psql=# CREATE TABLE measurement (

psql(#     city_id         int not null,

psql(#     logdate         date not null,

psql(#     peaktemp        int,

psql(#     unitsales       int

psql(# );

CREATE TABLE

psql=# CREATE TABLE measurement_y2006m02 (

psql(#     CHECK ( logdate >= DATE '2006-02-01' AND logdate < DATE '2006-03-01' )

psql(# ) INHERITS (measurement);

CREATE TABLE

psql=# CREATE TABLE measurement_y2006m03 (

psql(#     CHECK ( logdate >= DATE '2006-03-01' AND logdate < DATE '2006-04-01' )

psql(# ) INHERITS (measurement);

CREATE TABLE

psql=# 

psql=# 

psql=# ALTER TABLE measurement

ADD CONSTRAINT con1 PRIMARY KEY (city_id);

ALTER TABLE

psql=# 

psql=# 

-- Don't have primary key on child table

psql=# desc measurement_y2006m02

         Table "public.measurement_y2006m02"

  Column   |            Type             | Modifiers 

-----------+-----------------------------+-----------

 city_id   | integer                     | not null

 logdate   | timestamp without time zone | not null

 peaktemp  | integer                     | 

 unitsales | integer                     | 

Check constraints:

    "measurement_y2006m02_logdate_check" CHECK (logdate >= '01-FEB-06 00:00:00'::timestamp without time zone AND logdate < '01-MAR-06 00:00:00'::timestamp without time zone)

Inherits: measurement

-- Primary key on parent table

psql=# desc measurement

             Table "public.measurement"

  Column   |            Type             | Modifiers 

-----------+-----------------------------+-----------

 city_id   | integer                     | not null

 logdate   | timestamp without time zone | not null

 peaktemp  | integer                     | 

 unitsales | integer                     | 

Indexes:

    "con1" PRIMARY KEY, btree (city_id)

Number of child tables: 2 (Use \d+ to list them.)

I am not sure whether PRIMARY KEY not getting route is a expected behavior or not, but if its expected behavior

then obviously DROP CONSTRAINT should not complain about constraint doesn't exists on child table.

Inputs/Comments ?

Thanks,