"Markhof, Ingolf" <ingolf.markhof@xxxxxxxxxxxxxx> writes:
> I am really surprised that PostgreSQL is unable to keep the source text
> of a view. Honestly, for me the looks like an implementation gap.
Perhaps, but the "gap" is wider than you seem to think. Consider
CREATE TABLE t1 (f1 int, f2 text);
CREATE VIEW v1 AS SELECT f2 FROM t1;
ALTER TABLE t1 RENAME COLUMN f2 TO zed;
\d+ v1
View "public.v1"
Column | Type | Collation | Nullable | Default | Storage | Description
--------+------+-----------+----------+---------+----------+-------------
f2 | text | | | | extended |
View definition:
SELECT t1.zed AS f2
FROM t1;
At this point the original text of the view is useless; with
another rename or two it could become downright misleading.
Another issue revolves around the fact that a textual SQL statement
is seldom totally unambiguous. In the above example, the fact that
"t1" refers to public.t1 and not some other t1 depends on the
search_path as it stood at CREATE VIEW time. If you change your
search_path you might need an explicit schema qualification.
The reverse-parsed view display accounts for that:
# set search_path = pg_catalog;
# \d+ public.v1
View "public.v1"
Column | Type | Collation | Nullable | Default | Storage | Description
--------+------+-----------+----------+---------+----------+-------------
f2 | text | | | | extended |
View definition:
SELECT t1.zed AS f2
FROM public.t1;
but a static source text could not. In PG this hazard applies to
functions and operators not only tables. If pg_dump regurgitated
the original view text, there would be trivially-exploitable
security holes that allow some other user to take control of your
view after a dump/reload.
We actually used to store both text and parsed versions of some
sub-constructs, such as CHECK constraints and column default values.
We got rid of the text versions because there was no reasonable way
to keep them up-to-date. (And, AFAIR, there hasn't been a lot of
push-back about those catalog columns disappearing.) So I don't
think we'd accept a patch to store the text form of a view, unless
some solution to these issues were provided.
regards, tom lane
