Hi hackers,
I'd like to bring attention to a metadata visibility issue when multiple
schemas contain sequences with identical names, and a table column references
one of them via nextval(). Currently, there appears to be no reliable way to
determine which schema's sequence is actually referenced through system
catalogs or views.
Repro Steps:
1、Create same-named sequences in different schemas:
SQL:
CREATE SEQUENCE public.seq_xx_yy;
CREATE SEQUENCE schema_1.seq_xx_yy;
2、Create a table with a column defaulting to nextval('seq_xx_yy'):
SQL:
CREATE TABLE schema_1.test_tab_100 (c1 int DEFAULT nextval('seq_xx_yy'));
(At creation time, search_path resolves this to public.seq_xx_yy.)
3、Query metadata:
SQL:
SELECT column_default FROM information_schema.columns
WHERE table_name = 'test_tab_100'; -- Shows: nextval('seq_xx_yy'::regclass)
Neither information_schema.columns nor pg_sequences reveals the actual schema
of the referenced sequence.
Is this a known limitation?
JiaoShuntian
HighGo Inc.
