Is necessary to use SEQ_MAXVALUE in pg_dump?
I'm trying fix independence of pg_dump.c on postgres.h. And I found
following construct in dumpSequence function:
09391 snprintf(bufm, sizeof(bufm), INT64_FORMAT, SEQ_MINVALUE);
09392 snprintf(bufx, sizeof(bufx), INT64_FORMAT, SEQ_MAXVALUE);
09393
09394 appendPQExpBuffer(query,
09395 "SELECT sequence_name, last_value,
increment_by, "
09396 "CASE WHEN increment_by > 0 AND max_value = %s
THEN NULL "
09397 " WHEN increment_by < 0 AND max_value = -1
THEN NULL "
09398 " ELSE max_value "
09399 "END AS max_value, "
09400 "CASE WHEN increment_by > 0 AND min_value = 1
THEN NULL "
09401 " WHEN increment_by < 0 AND min_value = %s
THEN NULL "
09402 " ELSE min_value "
09403 "END AS min_value, "
09404 "cache_value, is_cycled, is_called from %s",
09405 bufx, bufm,
09406 fmtId(tbinfo->dobj.name));
This construct is used to determine if max_value/min_value is used and
after that pg_dump add NO MAXVALUE to the output instead of the value.
If I compare it with manual documentation NO MAXVALUE uses default value
and I do not see any reason to have this code there. I think we can
remove this code and release dependency on sequence.h.
Any comments?
Zdenek
Zdenek Kotala <Zdenek.Kotala@Sun.COM> writes:
This construct is used to determine if max_value/min_value is used and
after that pg_dump add NO MAXVALUE to the output instead of the value.
If I compare it with manual documentation NO MAXVALUE uses default value
and I do not see any reason to have this code there. I think we can
remove this code and release dependency on sequence.h.
IIUC you are proposing that it's okay to print random-huge-values in
the dumped CREATE SEQUENCE commands. I don't agree with that.
In particular it would make for a legacy/compatibility issue for
INT64_IS_BROKEN platforms.
A better solution might be to move the declarations of
SEQ_MINVALUE/SEQ_MAXVALUE someplace else.
regards, tom lane
Tom Lane wrote:
A better solution might be to move the declarations of
SEQ_MINVALUE/SEQ_MAXVALUE someplace else.
Hmm. It seems better, but it is also hard to find correct place. :( I'm
thinking put it into c.h.
Another question why sequence does not have separate flag which
determines if it is default/no max value or predefined?
Any comments, better ideas?
Zdenek
Zdenek Kotala <Zdenek.Kotala@Sun.COM> writes:
Tom Lane wrote:
A better solution might be to move the declarations of
SEQ_MINVALUE/SEQ_MAXVALUE someplace else.
Hmm. It seems better, but it is also hard to find correct place. :( I'm
thinking put it into c.h.
The idea that was in the back of my mind was pg_config_manual.h,
since these numbers could be seen as configuration constants if
you hold your head at the right angle ...
regards, tom lane