Re: isolation level

Oscar Goldes wrote: > > Hello, > Is there any "rule of thumb" about which isolation level to use when using > Informix SQL? I know, it all depends on the application, but what is the > "usual" level for a client-server system? > Can it be commited read, or must it be higher or lower? Of course, there > are special cases when another level shoul be used. > What is the impact over performance of using too high a level? > Many thanks > > -- Oscar Goldes > -- Orden Argentina SA Hi, databases using unbuffered or buffered logging will use the isolation level "committed read" by default. Maybe this is the best default level, but it's important to understand the result. What you will get are rows, that have been committed in the past. When you will fetch a row, this row could have been deleted *before* you fetched the row by your application. ( Your application will use a cursor buffer and therefore the set of rows inside the cursor buffer is "dirty" ). Bye Stefan