[Qt-interest] Huge amount of data in tree or whatever(view)

[Marek Bronowicki]

Hi Irfan

I mean that in first stage user gets all data from database.
Selecting 1 500 000 ecords in one time can kill anybody, so my point of 
view is to send a query to scrollbar like "SELECT count(*) FROM table" 
to gather count of all records, and to a view send a query "SELECT * 
FROM table LIMIT %d,50"
where %d is an int of begin of table.

for example:
if the scrollbar is on the top the %d = 0
if the scrollbar is one page down - %d = 51
etc.


Best Wishes for 2010 for you and all QT users and developers,
Marek Bronowicki

W dniu 2009-12-31 21:32, Irfan Omair pisze:
> Hi Marek,
>
> Do you mean even if you slect only 50 Rows from you DB to your table 
> veiew/tree view you still see long vertical scrollbar??
> Are you directly pulling and showing to your table veiw?? or Do you 
> pull the data from db and storing it in some stringlist and then 
> showing to your view?
>
> I had some similar problem issue which got solved when I stored the 
> data from db to stringlist and then shown all/few of those to my table 
> depending up on the business logic.
>
> Does this helps in any way?
>
> Regards,
> Irfan Omair
>
> On Thu, Dec 31, 2009 at 11:13 AM, Marek Bronowicki <marek at cyberdeus.pl 
> <mailto:marek at cyberdeus.pl>> wrote:
>
>     Hi
>
>     Perhaps this topic was "blended" and "sqashed" milions of times, but I
>     still cannot find a solution.
>
>     This is what I need to do:
>     I have one and a half milion of records in SQL database and I need to
>     show them all in some view.
>
>     What I know already that is that about 40000 records in treeview is a
>     total mass of information for my Athlon X2 2,0 to show and
>     pressing the
>     end key hangs the soft for about 10 seconds to get on the end of
>     the list.
>     My friend told me that this has to be model view, but after inserting
>     the same amount of data to model based view the result is the same.
>
>     I'm thinking about simple solution that can retrievie only shown rows
>     from the database with scrollbar as huge as the whole table. In
>     example:
>     My treeview or tableview or whateverview has height for 50 rows (let's
>     say 10 px for row so 500px without header bar), so:
>     my select query: "SELECT * FROM table LIMIT 0,50;" and this is shown
>     live on the treeview
>
>     but vertical scrollbar it's as big as "select * from table"
>
>     If i will press page down, the select query will change to SELECT
>     * FROM
>     table LIMIT 50,50;
>     the same with down arrow SELECT * FROM table LIMIT 1,50;
>     etc.
>
>     I don't know if i'm describing it right, or as usual only I'm
>     understanding what I'm writing:-)
>
>     Best Regards,
>     Marek Bronowicki
>
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