autogenerated column names + views are a dump hazard

Hi,

Kathy (CCed) just found a bug in BDR that turned out to actually be a
bug in postgres.

CREATE VIEW v_03 AS
SELECT * FROM (SELECT '2' ORDER BY 1) s;

postgres[l]=# \d+ v_03                  View "public.v_03"
┌──────────┬──────┬───────────┬──────────┬─────────────┐
│  Column  │ Type │ Modifiers │ Storage  │ Description │
├──────────┼──────┼───────────┼──────────┼─────────────┤
│ ?column? │ text │           │ extended │             │
└──────────┴──────┴───────────┴──────────┴─────────────┘
View definition:SELECT s."?column?"  FROM ( SELECT '2'::text         ORDER BY '2'::text) s;

Note the added cast to determine the type of the expression and the
generated column name.

If you dump/load that view definition, or even just execute the query
the fun starts:
postgres[1]=#  SELECT s."?column?"  FROM ( SELECT '2'::text            ORDER BY '2'::text) s;
ERROR:  column s.?column? does not exist
LINE 1: SELECT s."?column?

Due to the added explicit cast the generated column name now isn't
"?column?" but "text".


The easiest way to solve this would teach ruleutils.c to simply always
attach AS clauses for auto-generated columnnames. Won't look too pretty
though. Does somebody have a better idea?

Greetings,

Andres Freund

-- Andres Freund                       http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
Services