[Mono-dev] How to improve Dataset Performance

[Oskar Berggren]

2009/12/9 APS <dev.malst at apsystems.it>:
> For sure I can pass a test case, is better that I file a bug report? I think
> that Mono team already knows where datasets are slower than MS.Net and maybe
> can suggest me some "best practice".
> Btw with the code provided below with MS.Net on a standard developer machine
> and Mono on a bi-processor testing machine (with 2GB of ram):
>
> 1000 rows
> MS.Net: 130ms
> Mono 2.4.3:  1.2s
> Mono 2.0.1:  3.5s
>
> 10.000 rows
> MS.Net: less than a second
> Mono 2.4.3: 114s
> Mono 2.0.1: 361s


So when the data size increase by a factor of 10, on ms.net the time
taken also seem to increase by a factor of 10, but on mono by a factor
of 100. Seems like an an O(N) versus an O(N²) algorithm.

The code below contains a loop and you claim the Select part is taking
the most time. If that is true, it seems to indicate that ms.net
Select() for this case is O(1) but mono's O(N), with N being the
number of rows in the table.

/Oskar


> I have tables with more than 50.000 rows...I don't know how much it takes to
> perform the elaboration. RowFilter speed up only if applied on small
> rowsets.
> The problem is in the .Select method, removing those lines the elaboration
> is quicker in Mono. Testing machines are not with the same resources but the
> difference is too much to think to an hardware difference.
> Here is the code...
>
>             DataSet ds1 = new DataSet();
>             ds1.Tables.Add();
>             ds1.Tables[0].Columns.Add("COL1", typeof(string));
>             ds1.Tables[0].Columns.Add("COL2", typeof(int));
>             ds1.Tables[0].Columns.Add("COL3", typeof(bool));
>             for (int i = 0; i < 10000; i++) {
>                 ds1.Tables[0].Rows.Add(new object[] { "test", i, true });
>             }
>             DataSet ds2 = new DataSet();
>             ds2.Tables.Add();
>             ds2.Tables[0].Columns.Add("COL1", typeof(string));
>             ds2.Tables[0].Columns.Add("COL2", typeof(int));
>             ds2.Tables[0].Columns.Add("COL3", typeof(bool));
>             for (int i = 0; i < 10000; i++) {
>                 ds2.Tables[0].Rows.Add(new object[] { "test", i, true });
>             }
>             DataSet ds3 = new DataSet();
>             ds3.Tables.Add();
>             ds3.Tables[0].Columns.Add("COL1", typeof(string));
>             ds3.Tables[0].Columns.Add("COL2", typeof(int));
>             ds3.Tables[0].Columns.Add("COL3", typeof(bool));
>             for (int i = 0; i < 10000; i++) {
>                 ds3.Tables[0].Rows.Add(new object[] { "test", i, true });
>             }
>             int idx=0;
>             foreach (DataRow dr in ds1.Tables[0].Rows) {
>                 DataRow[] dr2 = ds2.Tables[0].Select("COL2=" + idx);
>                 DataRow[] dr3 = ds3.Tables[0].Select("COL2=" + idx);
>
>                 idx++;
>             }
>
>
>
>
> At 21.59 02/12/2009, Nagappan Alagappan wrote:
>
> Hello,
>
> Do you have a test case to reproduce this issue, which you could share with
> the Mono team ?
>
> Thanks
> Nagappan
>
> On Wed, Dec 2, 2009 at 4:05 AM, APS <dev.malst at apsystems.it > wrote:
> Hi,
>
> I'm testing some old elaboration that cycles on a large datatable and
> for every rows makes several selections on separated datatables.
> This elaboration is really slow on mono and fast on MS.NET, let say
> 400secs vs 4 secs.
> It seems that last rows are slower that first rows.
> I made some test on datasets scroll and I saw that mono performance
> is better than MS.NET so the delay is due to inner selections.
> I changed datatable.select in defaultview.sort and I gained 200secs,
> still too slow.
> Now I've identified some datatable.compute as the main delay source.
> I'll try to change them using Linq but the question is: there's some
> known performance problem in dataset heavy usage, there's some best
> pratice that you can suggest to speed up elaborations?
> Thanks in advance.
>
>
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