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Filtering questions |
Wed, Oct 10 2007 5:04 AM | Permanent Link |
"Harry de Boer" | LS
sessiontype=stRemote 1) If I first apply a filter to a TEDBTable component and set filtered = true and then opening that EDBtable; will it only fetch the filtered rows or will it open the table first and then fetch the rows? 2) The same for a TEDBQuery: will it execute (open) the query first and then apply the filter, or will it take the filter in consideration when opening the query? 3) How do views behave in this matter, like a table or a query? 4) Is there a difference between local and remote regarding this? The reason for this questions is that we want to let endusers use a 'visual filter' component with which a user can apply filters on the fly. We want however to apply a filter before opening a table/query to have no records to start with (custID=0). If the visual filter filtertext = '' we then in the onchange event want to set the original filter back, so that the enduser never retrieves all the data. Regards, Harry . |
Wed, Oct 10 2007 8:50 AM | Permanent Link |
Tim Young [Elevate Software] Elevate Software, Inc. timyoung@elevatesoft.com | Harry,
<< 1) If I first apply a filter to a TEDBTable component and set filtered = true and then opening that EDBtable; will it only fetch the filtered rows or will it open the table first and then fetch the rows? >> It will open the table first, fetch some rows, filter the table, and then fetch some rows again. << 2) The same for a TEDBQuery: will it execute (open) the query first and then apply the filter, or will it take the filter in consideration when opening the query? >> Same situation. << 3) How do views behave in this matter, like a table or a query? >> Same situation. << 4) Is there a difference between local and remote regarding this? >> No, nothing apart from the fact that the remote session is thunking the filtering calls, etc. over the wire. << The reason for this questions is that we want to let endusers use a 'visual filter' component with which a user can apply filters on the fly. We want however to apply a filter before opening a table/query to have no records to start with (custID=0). If the visual filter filtertext = '' we then in the onchange event want to set the original filter back, so that the enduser never retrieves all the data. >> At the most, EDB will only retrieve the number of rows needed to satisfy any data-aware controls such as a grid, or only 1 row if there aren't any grids connected. -- Tim Young Elevate Software www.elevatesoft.com |
Mon, Oct 22 2007 5:50 AM | Permanent Link |
"Harry de Boer" | Tim,
> At the most, EDB will only retrieve the number of rows needed to satisfy any > data-aware controls such as a grid, or only 1 row if there aren't any grids > connected. Does that mean you could use the QG from devexpress where you -open the table (only retrieve the number of VISIBLE rows needed to fill the first visible (let's say) 25 records of the QG) -could filter on a name with z* (which is not visible till then) and then only the records are retrieved that are filtered Reason for asking this is that I read some posts (fulltextsearch.com) where people state that you could only use a filter when the whole table is loaded. Maybe someone uses the QG and could give me some info here (I'm thinking of buying QG) Regards, Harry "Tim Young [Elevate Software]" <timyoung@elevatesoft.com> schreef in bericht news:74659CDE-55BF-4950-BEB4-7C3B5356D917@news.elevatesoft.com... > Harry, > > << 1) If I first apply a filter to a TEDBTable component and set filtered = > true and then opening that EDBtable; will it only fetch the filtered rows or > will it open the table first and then fetch the rows? >> > > It will open the table first, fetch some rows, filter the table, and then > fetch some rows again. > > << 2) The same for a TEDBQuery: will it execute (open) the query first and > then apply the filter, or will it take the filter in consideration when > opening the query? >> > > Same situation. > > << 3) How do views behave in this matter, like a table or a query? >> > > Same situation. > > << 4) Is there a difference between local and remote regarding this? >> > > No, nothing apart from the fact that the remote session is thunking the > filtering calls, etc. over the wire. > > << The reason for this questions is that we want to let endusers use a > 'visual filter' component with which a user can apply filters on the fly. We > want however to apply a filter before opening a table/query to have no > records to start with (custID=0). If the visual filter filtertext = '' we > then in the onchange event want to set the original filter back, so that the > enduser never retrieves all the data. >> > > At the most, EDB will only retrieve the number of rows needed to satisfy any > data-aware controls such as a grid, or only 1 row if there aren't any grids > connected. > > -- > Tim Young > Elevate Software > www.elevatesoft.com > > |
Mon, Oct 22 2007 8:59 AM | Permanent Link |
Roy Lambert NLH Associates Team Elevate | Harry
I don't use QuantumGrid (I've bought the TMS stuff) but don't confuse its internal sorting/filtering system with the connected database. To use the grids internal functions you're almost guaranteed to have to load the entire table. Roy Lambert |
Mon, Oct 22 2007 9:17 AM | Permanent Link |
Eryk Bottomley | Harry
> Does that mean you could use the QG from devexpress where you > -open the table (only retrieve the number of VISIBLE rows needed to fill the > first visible (let's say) 25 records of the QG) > -could filter on a name with z* (which is not visible till then) and then > only the records are retrieved that are filtered Depends if the grid is in 'GridMode' or not (the default is 'not'). > Reason for asking this is that I read some posts (fulltextsearch.com) where > people state that you could only use a filter when the whole table is > loaded. Maybe someone uses the QG and could give me some info here (I'm > thinking of buying QG) They are referring to the QGrid built in filtering capability which is not dependent on the underlying database (if any - a QGrid does not need to be tied to a database at all). If 'GridMode' is active then the QGrid behaves much like a normal TDBGrid in terms of requesting records and its own filtering capabilities are disabled. If 'Gridmode' is not active then all the records from the attached dataset are downloaded and buffered in memory which the grid can then filter and sort locally without reference to the underlying dataset. Eryk |
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