RecordSet download

valerio_pittavino · February 23, 2015, 6:20pm

Hi everyone,
I have a problem with recordset and MySQL, I need to interrupt a download of recordset but I can’t. I write an simple example:

Dim Rs as recordSet=DB.SQLSelect(“Select * from myTable”)
…

now RealStudio starts to download datas but I can’t interrupt it, I tried to execute this code in a thread but if I kill the thread the download continues, this is a problem beacause an user in my application can choose to download a very big table (may be an mistake) and he can’t interrupt this operation.

Another question, can I check Recordset download status? How?

Travis_McBride · February 23, 2015, 6:46pm

Check out the DownloadContainer.xojo_xml_project example in your Xojo Folder. Might help out

Christian_Schmitz · February 23, 2015, 7:07pm

maybe you use LIMIT keyword and only query the fields you need?

valerio_pittavino · February 23, 2015, 7:51pm

Yes, to use LIMIT is a solution but I would like to know how observe progress download. I have a reason, when I do a query I call a view, this view contains a lot of rows, now it can be have about 600000 rows, if I use LIMIT I must interrogate more time the table and this operation can become slow the software.

Bob_Coleman · February 23, 2015, 7:54pm

I would grab the record count first by executing COUNT then process in appropriate size chunks by using LIMIT on my SELECT.

valerio_pittavino · February 23, 2015, 8:03pm

Thanks for your replies, I will use yours advice, I will create a class to create a temporary table to write result of query (in this system I must do 1 call to the view) and after I will download datas from temporary table using limit. I’m interested to this because I want to know dimension of data to download, to get valued time to end of download ecc.
Creating a good class I will use it in all project to download big datas and I will use it in threads.

Tim_Hare · February 23, 2015, 9:10pm

There is no way to interrupt the transfer of data or to monitor its progress.

Christian_Schmitz · February 23, 2015, 9:33pm

600000? Sounds you may have other problems.

One thing could be to make sure you have server side records, so only one at a time is transferred and not all of them.
With MBS SQL plugin you can specify how many records are loaded in a batch. And of course turning off Scrollable feature will help in this case. (scrollable cursors are often client side)

valerio_pittavino · February 23, 2015, 9:44pm

I don’t allow to the user to download all, only if he want make a backup he can.
Normally the user downloads less datas in one time, but if he try to download too datas the program allow to interupt the download.
I just finished the class, it is only a base but works