Hi Ewan, On Fri, Jun 12, 2026 at 1:02 PM Amit Langote <[email protected]> wrote: > On Fri, Jun 12, 2026 at 12:36 PM Ewan Young <[email protected]> wrote: > > > > Hi, > > > > Commit 2da86c1 ("Add fast path for foreign key constraint checks") makes > > a foreign-key column whose type is a domain over a type different from > > the referenced PK reject every valid row: > > > > CREATE DOMAIN int8dom AS int8; > > CREATE TABLE pk (a int4 PRIMARY KEY); > > CREATE TABLE fk (b int8dom REFERENCES pk(a)); > > INSERT INTO fk VALUES (1); > > ERROR: no conversion function from int8dom to integer > > > > It's new in v19 (verified by building 2da86c1^, where the insert > > succeeds); no released version is affected. The SPI path still handles > > it fine, e.g. with a partitioned PK. > > > > The fast path is the first caller to pass the cross-type pf_eq_oprs > > operator to ri_HashCompareOp(). Its "no cast needed" test, > > > > if (typeid == righttype) > > > > fails when the FK column is a domain over righttype (typeid is the > > domain OID), so it wrongly concludes no conversion exists and errors out. > > Looking through the domain fixes it -- conpfeqop is chosen against the > > FK base type, so getBaseType(typeid) == righttype holds for any valid FK: > > > > - if (typeid == righttype) > > + if (getBaseType(typeid) == righttype) > > > > Patch attached, with a regression test in foreign_key.sql. make check > > and the isolation suite pass. > > Thanks for the report and the patch. Will look next week.
Your analysis looks correct and the patch makes sense. I looked through the code and convinced myself the new check is valid. One nuance: "holds for any valid FK" is true when pfeqop comes directly from the index opfamily (right-hand input getBaseType(fktype)). The PK = PK fallback uses opcintype instead, but there getBaseType can't equal it either, so the test still fails and the existing cast lookup runs unchanged. I polished it a bit for commit: tightened the message and trimmed the code comment. Will push to master tomorrow barring objections. -- Thanks, Amit Langote
v2-0001-Fix-RI-fast-path-for-domain-typed-FK-columns.patch
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