Re: support virtual generated column not null constraint

On Fri, Mar 28, 2025 at 10:06 PM Peter Eisentraut <peter(at)eisentraut(dot)org> wrote:
>
> On 24.03.25 04:26, jian he wrote:
> > rebase, and some minor code comments change.
>
> I have committed this.
>
In an earlier thread, I also posted a patch for supporting virtual
generated columns over domain type.
The code is somehow similar,
so I post the remaining patch to this thread.

v7-0001
we need to compute the generation expression for the domain with constraints,
thus rename ExecComputeStoredGenerated to ExecComputeGenerated.

v7-0002
soft error variant of ExecPrepareExpr, ExecInitExpr.
for soft error processing of CoerceToDomain.
we don't want error messages like
"value for domain d2 violates check constraint "d2_check""
while validating existing domain data,
we want something like:
+ERROR: column "b" of table "gtest24" contains values that violate
the new constraint

v7-0003
supports virtual generation columns over domain type.
If the domain has constraints then we need to compute the virtual
generation expression,
that happens mainly within ExecComputeGenerated.

if a virtual generation column type is domain_with_constraint, then
ALTER DOMAIN ADD CONSTRAINTS need to revalidate these virtual
generation expressions again.
so in validateDomainCheckConstraint, validateDomainNotNullConstraint
We need to fetch the generation expression (build_generation_expression),
compile the generation expression (ExecPrepareExprSafe),
and evaluate it (ExecEvalExprSwitchContext).

I also posted patch summary earlier at [1]
[1] https://postgr.es/m/CACJufxHT4R1oABzeQuvjb6DHrig7k-QSr6LEe53Q_nLi9pfanA@mail.gmail.com