Alvaro Herrera <alvhe...@alvh.no-ip.org> 于2024年8月31日周六 11:59写道：
> Hello > > Here I present another attempt at making not-null constraints be > catalogued. This is largely based on the code reverted at 9ce04b50e120, > except that we now have a not-null constraint automatically created for > every column of a primary key, and such constraint cannot be removed > while the PK exists. Thanks to this, a lot of rather ugly code is gone, > both in pg_dump and in backend -- in particular the handling of NO > INHERIT, which was needed for pg_dump. > > Noteworthy psql difference: because there are now even more not-null > constraints than before, the \d+ display would be far too noisy if we > just let it grow. So here I've made it omit any constraints that > underlie the primary key. This should be OK since you can't do much > with those constraints while the PK is still there. If you drop the PK, > the next \d+ will show those constraints. > > One thing that regretfully I haven't yet had time for, is paring down > the original test code: a lot of it is verifying the old semantics, > particularly for NO INHERIT constraints, which had grown ugly special > cases. It now mostly raises errors; or the tests are simply redundant. > I'm going to remove that stuff as soon as I'm back on my normal work > timezone. > > sepgsql is untested. > > I'm adding this to the September commitfest. > The attached patch adds List *nnconstraints, which store the not-null definition, in struct CreateStmt. This makes me a little confused about List *constraints in struct CreateStmt. Actually, the List constraints store ckeck constraint, and it will be better if the comments can reflect that. Re-naming it to List *ckconstraints seems more reasonable. But a lot of codes that use stmt->constraints will be changed. Since AddRelationNewConstraints() can now add not-null column constraint, the comments about AddRelationNewConstraints() should tweak a little. "All entries in newColDefaults will be processed. Entries in newConstraints will be processed only if they are CONSTR_CHECK type." Now, the type of new constraints may be not-null constraints. If the column has already had one not-null constraint, and we add same not-null constraint again. Then the code will call AdjustNotNullInheritance1() in AddRelationNewConstraints(). The comments before entering AdjustNotNullInheritance1() in AddRelationNewConstraints() look confusing to me. Because constraint is not inherited. -- Tender Wang
