From: | Claudio Freire <klaussfreire(at)gmail(dot)com> |
---|---|
To: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
Cc: | Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Expression indexes and dependecies |
Date: | 2013-07-22 21:12:10 |
Message-ID: | CAGTBQpYCGUyOHx1D6HHDadOaX5BMLrrTiMFVT9sudFWeEJW94A@mail.gmail.com |
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On Mon, Jul 22, 2013 at 6:04 PM, Alvaro Herrera
<alvherre(at)2ndquadrant(dot)com> wrote:
> Pavan Deolasee escribió:
>> Hello,
>>
>> While doing some tests, I observed that expression indexes can malfunction
>> if the underlying expression changes.
>
> [...]
>
>> Perhaps this is a known behaviour/limitation, but I could not find that in
>> the documentation. But I wonder if it makes sense to check for dependencies
>> during function alteration and complain. Or there are other reasons why we
>> can't do that and its a much larger problem than what I'm imagining ?
>
> This is a tough problem. The dependency mechanism has no way to keep
> track of this kind of dependency; all it does is prevent the function
> from being dropped altogether, but preventing it from acquiring a
> conflicting definition is outside its charter.
>
> One way to attack this would be registering dependencies of a new kind
> on functions used by index expressions. Then CREATE OR REPLACE function
> could reject alteration for such functions. I don't know if we care
> enough about this case.
What about a warning and leave it to the dba to reindex?
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