Tom Lane wrote:
> "Mark Hollomon" <mhh@nortelnetworks.com> writes:
> > Just out of curiousity, is there technical reason there isn't
> > a (say) relisview attribute to pg_class?
>
> That might indeed be the most reasonable way to attack it, rather
> than having to go messing about looking for a matching rule.
> (Jan, any thoughts here?)
The right way IMHO would be to give views another relkind. Then we could easily
1. detect if the final query after rewriting still tries to INSERT/UPDATE/DELETE a view - i.e. "missing
rewrite rule(s)".
2. disable things like LOCK etc.
The problem here is, that the relkind must change at rule creation/drop time. Fortunately rules on SELECT
aretotally restricted to VIEW's since 6.4, and I don't see any reason to change this.
And it's time to make more use of the relkind attribute. For 7.2, when we want to have tuple-set returns for
functions,we might want to have structures as well (we talked about that already, Tom). A structure is just a
row/typedescription. A function, returning a tuple or set of tuples, can return this type or set of type as well
asany other existing table/view structure. So to create a function returning a set of tuples, which have a
structuredifferent from any existing table, someone creates a named structure, then the function
returningtuples of that type. These structures are just entries in pg_class, pg_attribute and pg_type. There
isno file or any rules, triggers etc. attached to them. They just describe a typle that can be built in memory.
> Adding a column to a core system table like pg_class is a good
> exercise for the student ;-) ... it's not exactly automated,
> and you have to find all the places that need to be updated.
> You might want to keep notes and prepare a writeup for the
> developer's FAQ. I thought of that the last time I did something
> similar, but it was only at the end that I realized I should've
> been keeping notes to start with.
Meetoo :-}
Jan
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