--- In firebird-support@yahoogroups.com, "Carlos H. Cantu" <listas@...> wrote:

>
> z> 3. If your database is updated a lot, and you use default .net
> z> transaction (IsolationLevel.ReadCommitted) while reading data,
> z> WRITERS BLOCK READERS.
>
> A ReadCommited transaction can see commited records by transactions
> that were started after the ReadCommited one. It is not true that
> writers block readers.
>
> Carlos
> Firebird Performance in Detail - http://videos.firebirddevelopersday.com
> www.firebirdnews.org - www.FireBase.com.br
>

I had problems with this in the past.
If i start reading data using IsolationLevel.ReadCommitted on a time consuming query, and table gets heavily updated in meantime, data reading gets stucked until updating is done.
This is desirable behavior for issuing flight tickets, but for showing sport results or showing reports it's a problem.
If i specify IsolationLevel.RepeatableRead there is no problem.
Check this out:
http://firebird.1100200.n4.nabble.com/Writer-block-reader-issue-td1106813.html
Truth to be said, it was quite while ago, and i'm not sure that
IsolationLevel.ReadCommitted internals have changed.