Any modern database uses a "cost-based optimizer" to determine its query execution plans. This means that at a minimum the database knows how many rows each table contains. This means that you just have to find this metadata -- then you can use that in lieu an actual count(*).
On oracle you would: select num_rows from all_tables where owner = 'FOO' and table_name = 'BAR'; instead of select count(*) from foo.bar On 6/29/07, "C. Bergström" <[EMAIL PROTECTED]> wrote: > Gwyn Evans wrote: > > Hi, > > > > Anyone got any suggestions as to the best way to provide a paging > > data view without requiring using size() to actually count the records > > in DB? > > > > I've got a site that has a production DB such that > > "select COUNT(*) from mytable" > > takes a non-trivial amount of time/cpu to return, whereas to get > > the actual data for the page is effectively immediate! > > > > I'm curently using a DefaultDataTable and the quick hack is to just > > hard-code DataProvider.size() to just return a fixed number, but while > > that's probably OK, it's sub-optimal (it is just a util for my own > > use though, really). Having said that, I'd be interested in > > alternative suggestions. > > > > It's the Production DB only that shows this behaviour (which is > > probably related to them not purging the the old data for 4 years or > > so, so I'm limited as to what might be possible with the DB itself). > > > I smell Postgres and just going to go out on a limb here.. :) triggers > that update a counts table, db maintenance, or search the postgres > "perform" archive for other ways to achieve this.. I'm pretty sure I see > this question nearly every two weeks and from what I've read and > remember it pretty much falls on the responsibility of the backend. > There's also certainly more commentary in the wicket-users archives as well. > > Good luck, > > ./C > > ------------------------------------------------------------------------- > This SF.net email is sponsored by DB2 Express > Download DB2 Express C - the FREE version of DB2 express and take > control of your XML. No limits. Just data. Click to get it now. > http://sourceforge.net/powerbar/db2/ > _______________________________________________ > Wicket-user mailing list > Wicket-user@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/wicket-user > -- Scott Swank reformed mathematician ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Wicket-user mailing list Wicket-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/wicket-user
