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Subject: re: Why ArrayList with Unknown Result Count?
Date: Sun, 29 Nov 2009 13:31:52 +0100
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Message-ID: <B297D4737108A0459B66C3A85BB7F901147678@kn.esteam.de>
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Thread-Topic: re: Why ArrayList with Unknown Result Count?
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From: =?iso-8859-1?Q?Rainer_D=F6bele?= <doebele@esteam.de>
To: <empire-db-dev@incubator.apache.org>

Hi Amin,

these functions are provided for convenience only and are indeed =
intended for small result sets.
For special needs people can implement their own function - in fact they =
should use a DBReader.

But what we could easily do, is to provide an overload for those =
functions that allow to supply the collection. Hence the use can decide =
which collection to use.
I will create an JIRA issue for this too.

Thanks again
Rainer


Amin Abbaspour wrote:
> re: Why ArrayList with Unknown Result Count?
>=20
> Hello everyone,
>=20
> This is my first email in empire-db's developers mailing list :) First
> of all thanks for your ideas and attempts.
>=20
> I was reading source code and noticed that ArrayList is used to store
> results in querySimpleList and queryObjectList and also to hold values
> in tables, relations, and views.
>=20
> While the second usage (for tables, relations, etc) is not much
> critical since they are limited in size, IMHO using ArrayList without
> initial size is prohibited for large datasets such as those returned =
by
> queries. As you all know this will result in many times memory
> allocation and collection since it goes from size 10 -> 20 -> 40 ->
> etc.
>=20
> I recommend that in the cases that there is a known return value count
> (like selectSingle or select with Limit value), ArrayList should be
> used with initial size in constructor; otherwise LinkedList is a =
better
> choice.
>=20
> Regards,
> Amin Abbaspour
>=20
>=20
>=20
>=20