Devart Forums

Hi,
I am helping a customer with some software development.
They use UniDAC. At some point in time I have set a UniDAC Query to UniDirectional and FetchRows to 50000 records to avoid memory problems, they have millions of tuples in the database with hundreds of fields on each tuple.
Basically they run through the recordset and for each database-record the create a delphi-record and keep this in a sortable list.
It works perfectly. Memory consumption works now better, as the unidac records are released every time we get to retreiving more tuples.
But it only works perfectly when the exe-file is run locally. So let's say we have a client machine and a database server.
If, however the exe-file is installed on an application server, with a shared drive, and I run the application from a remote path like \\myserver\myApp\Databaseapp.exe something weird happens with performance.
I have timed the calls to query.open, and what we have and seemingly actually retreiving the data goes fine. But calls to retreiving data out of a dataset record and/or calling query.next is really messing something up.

So
myrec.Info1 := query.Fields[1].asString;
myrec.info2 := query.Fields[2].asString;

followed by query.next;

Is really really really slow if the executable is on a remote drive, but only with UniDirectional := true and FetchAll := False;

Running through a million records (and handling whatever handling needs done) takes :
Unidirection := true; FetchAll := False; RemoteDrive ==> 1 hour (give or take).
UniDirection := true; FetachAll := False; LocalDrive ==> 5 minutes
UniDirection := False; FetchAll := True; RemoteDrive ==> 6 minutes
UniDirection := False; FetchAll := True; LocalDrive ==> 5 minutes.

So, the combination of a remote drive, Unidirectional and Fetchall is false has a serious impact.

Can anyone give a fair explanation of why? I mean I understand there should be an impact on running on a remote drive, but why is this impact 12-fold in this exact combination??

Thanks in advance
Jens Fudge

Please explain which database do you use in your project. Are the conditions under which all the 4 tests you refer to are the same (downloading the network, using other users' databases when running tests, etc.)?

This is on a SQL Server 2016.
The conditions are the same on all 4 tests

Hi
Did you come up with any ideas why I get this behaviour?
For me, it doesn't make sense at all.

Jens

Unfortunately, we can't reproduce issues. To investigate this behavior of UniDAC, please compose a full sample demonstrating the issue and send it to us, including database objects creating scripts.