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Search 100 strings efficiently in a datatable or datagridview with 30000 rows

Hello,

I am looking for 100 strings in a datagridview with 30000 rows. Iterating the datagridview 30000 times in an outer for loop and iterating another inner for loop 100 times and check if the searched string is found seems not efficiently because it means a iterating a loop 30000 x 100 = 3.000.000 times WoW...

What I want is if I found the string in a row of the datagridview is to set the whole row`s backcolor red and the first column which has a checkbox to true.

All 30000 rows are in the MyExtendedReader which is populated with the database data.

How can I search the DataGridView/DataTable fast?


this is how my DataGridView is populated:
 
DataView MyDataView = new DataView(MyDataTable);
MyDataView.Table.Load(MyExtendedReader)
MyDataGridView.DataSource = MyDataView;

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MSFanboy
Asked:
MSFanboy
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1 Solution
 
williamcampbellCommented:
Only a certain number of rows are visible at any one time -

You need to intercept an event that will give you the displayable rows and only search those for the 100 strings.

Optimizations
If there can be only 1 occurance of a string in the 100 strings then eliminate it from the 100 each time it's found
If you find a String in a row break off the search

Otherwise you will need to rethink your Data by detecting if some of the 100 strings occurs in a row as it is added to the database. Add new fields 'StringFound' or 'RowHasString'  then use that to hilight it.

The 30000 x 100 problem is a n2 Algorithm problem, worst case you will have to do 3000000 compares



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Walter RitzelSenior Software EngineerCommented:
Hi,

my suggestion would be the following: independently from your will, the gridview will run over your 30000 rows anyways, but at least it will run over each according to your paging size.
My suggestion would be execute the search over each row during the rowdatabound event. And on the same event you can highlight the rows.

Regards,
Walter.
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MSFanboyAuthor Commented:
@wpcortes 
I found no RowDataBound event in DataGridView for .NET ?  I do not use asp.net ...
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MSFanboyAuthor Commented:
@wpcortes
this is the pendant in .net for RowDataBound event:
Event RowsAdded
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MSFanboyAuthor Commented:
The idea with running the compare in the events is nice could have be mine ;-) thx a bunch!
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