#27090: pg_get_serial_sequence is broken on postgres, use a lookup in
information_schema.columns instead
-------------------------------------+-------------------------------------
Reporter: Hanne Moa | Owner: nobody
Type: | Status: new
Cleanup/optimization |
Component: Database layer | Version: 1.10
(models, ORM) |
Severity: Normal | Resolution:
Keywords: postgres sequence | Triage Stage:
| Someday/Maybe
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by Hanne Moa):
The postgres-general list has some very interesting spam filters, took a
while to get through. (Don't have a line in the body of the email starting
with the word "which"...)
https://www.postgresql.org/message-id/nu7ebq%24a2h%241%40blaine.gmane.org
A different query is suggested, the result need not be parsed:
"Personally, I'd try looking in pg_depend to see if the column's default
expression has a dependency on a relation of type sequence. That avoids
all the fun of parsing the expression and turns it into a simple SQL
join problem." -- Tom Lane
It's a very simple join =):
{{{
select sn.nspname as sequence_schema, s.relname as sequence_name,
col.attname
from pg_class s
join pg_namespace sn on sn.oid = s.relnamespace
join pg_depend d on d.refobjid = s.oid and
d.refclassid='pg_class'::regclass
join pg_attrdef ad on ad.oid = d.objid and d.classid =
'pg_attrdef'::regclass
join pg_attribute col on col.attrelid = ad.adrelid and col.attnum =
ad.adnum
join pg_class tbl on tbl.oid = ad.adrelid
join pg_namespace n on n.oid = tbl.relnamespace
where s.relkind = 'S'
and d.deptype in ('a', 'n')
and n.nspname = 'public'
and tbl.relname = 'THE_TABLE_NAME'
and col.attname = 'THE_COLUMN_NAME'
}}}
Anyway, even using the information_schema, it might return a schema in
addition to the name so adjustments need to be made to my existing code.
--
Ticket URL: <https://code.djangoproject.com/ticket/27090#comment:14>
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