Обсуждение: pg_dump error

"mike" <matrix@quadrent.net> writes:
> dumpSequence(pilgram_en_id_seq): different sequence name returned by SELECT=
> : pilgram_cross_id_seq

> I'm not sure what this means, and I have no idea how to corect it.

Looking at the source code, it would seem that pg_dump is unhappy
because "SELECT sequence_name FROM pilgram_en_id_seq" returned
"pilgram_cross_id_seq" instead of the expected "pilgram_en_id_seq".

I'm not sure why exactly pg_dump is bothering to make such a
cross-check, but probably the more interesting question is how the
sequence got that way.  Did you rename it at some point?

I find that "ALTER TABLE RENAME" will work without complaint on a
sequence.  Seems we should either
  (a) prohibit renaming a sequence;
  (b) improve ALTER TABLE RENAME to know about changing the
      sequence_name field as well;
  (c) remove this cross-check from pg_dump; and/or
  (d) remove the sequence_name field from sequences entirely.

(c) looks like the path of least resistance.  I don't like (d) because
of the risk of breaking existing application code that might look at
the contents of sequences.  Comments?

            regards, tom lane

> I find that "ALTER TABLE RENAME" will work without complaint on a
> sequence.  Seems we should either
>   (a) prohibit renaming a sequence;
>   (b) improve ALTER TABLE RENAME to know about changing the
>       sequence_name field as well;
>   (c) remove this cross-check from pg_dump; and/or
>   (d) remove the sequence_name field from sequences entirely.
>
> (c) looks like the path of least resistance.  I don't like (d) because
> of the risk of breaking existing application code that might look at
> the contents of sequences.  Comments?

I know for a particular program I wrote, I wrote function that you feed it a
tablename and the serial fieldname and it spits back the currval, or the
nextval. I don't foresee renaming these fields or the sequences, but things
change.

It seems like (b) provides the most straightforward and predictable
behavior. Then again, I don't have to code it :)

Greg