Do ADO.Net DataTables have indexes?

Question

I am using VSTS 2008 + C# + .Net 3.5 + SQL Server 2008 + ADO.Net. If I load a table from a database by using a DataTable of ADO.Net, and in the database table, I defined a c

Answer 1

My reading of the docs is that the correct way to achieve this (if needed) is to use AsDataView to produce a DataView (or LinqDataView) that's bound to the underlying table. If your DataTable is invariant then the DataView can be static to avoid redundant re-indexing.

I am currently investigating Linq to DataSet, and this q was helpful to me, so thanks.

Answer 2

DataTables are indexed if you (the coder) specify one or more DataColumns as the Primary Key. Interally ADO.NET uses a Red-Black tree to form this index giving log-time lookups. This Primary Key is not set automatically based on any underlying keying from the data provider.

Answer 3

I had the same problem with many queries from a large datatable that are not according to the primary key.

The solution I found was to create DataView for each index I wanted to use, and then use it's Find and FindRows methods to extract the data.

DataView creates an internal index on the DataTable and behaves virtually as an index for this purpose.

In my case I was able to reduce 10,000 queries from 40 Seconds to ONE!!!

Answer 4

Others have made the point that a DataSet is not intended to serve as a database system--just a representation of data. If you are working under the impression that a DataSet is a database then you are mistaken and might need to reconsider your implementation.

If you need a client-side database, consider using SQL Compact or SQL Lite, both are free redistributable Database systems which can be used without requiring separate installations or services. If you need something more full-featured the SQL Express is the next step up.

To help clarify though, DataSets/Tables are used in .NET development to temporarily hold data as needed. Think of them as the results of a SELECT query against a database; they are roughly similar to CSV files or other forms of tabular data--you can pull data into them from a database, work with the data, and then push the changes back to a database--but they, on their own, are not databases.

If you have a large collection of items which you need to keep in memory for one reason or another then you might consider building a lightweight DTO (data transfer object, Google it, they're very simple) and loading them into a HashTable. HashTables won't give you any form of relational data, but are very efficient at look-ups.

Answer 5

You can create a primary key for the datatable. Filter operations get a big boost if you are searching in the primary key field. Check out this link: here