[odb-users] update object without caching the query result

[Tim Tao]

Hi Boris,

Thanks for your reply.

The following is the code fragment:

using query = odb::query<A>;
using result = odb::result<A>;

result r(db->query<A>(some conditions here));

for(result::iterator::iterator i (r.begin()); i != r.end(); ++i){
            shared_ptr<A> ptr = i.load();
            ptr->field = new_value;
            db->update(ptr);
}

So in this way I have to cache each result which seems unnecessary to me since I don't need them in the future once I finished updating

I wonder if there is any way I can update the results without loading them to cache ?

By the way, I am using postgres

Thanks,

Tim
________________________________________
From: Boris Kolpackov <boris at codesynthesis.com>
Sent: Thursday, September 24, 2015 10:26 AM
To: Tim Tao
Cc: odb-users at codesynthesis.com
Subject: Re: [odb-users] update object without caching the query result

Hi Tim,

Tim Tao <Tim.Tao at akunacapital.com> writes:

> Is there any way we can update an object without caching the
> query result ?
>
> I query the database and load() each result, it seems like this
> will cache the result in the application memory which is unnecessary.

There is a "query result", i.e., what's returned by the call to
query(), which, for some databases, may involve caching of the raw
data. When you call load() (presumably on result::iterator), you
load the "object". When you say "will cache the result", which
one do you refer to?

Also, it is always a good idea to show the code fragment.

Boris
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Tim Tao | Junior Developer

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