Hi All!
I found why this error, described in my previous comment, happens:
"2. Why the error, I described, happens? it's defenitely because of some troubles in PQ. It starts to happen after of quite long work in PQ UI. And as soon as it starts to happen - it happens more and more often. But if you close PQ window (but not
close Excel), and then launch PQ window again - the error disappears and all works fine. For some time ;-)."
This is because there is an error in reading context of Excel sheets/tables. While reading metadata of Excel file, all works fine, but as soon as reading of the data themselves happens. You can see that only through tracing, data are read successfully,
from end user point of view.
BUT - it is read with a noticeable delay. That happens because:
1. If the error happens, a great number of exceptions shown in trace.
2. As I described earlier, in case of error every step of refreshable Query is refreshed. But it seems for me,that it is true not only for refreshed query, but for all the previous as well! Even cashing doesn't work quite often, and PQ makes a lot of request of external data source.
1. If the error happens, a great number of exceptions shown in trace.
2. As I described earlier, in case of error every step of refreshable Query is refreshed. But it seems for me,that it is true not only for refreshed query, but for all the previous as well! Even cashing doesn't work quite often, and PQ makes a lot of request of external data source.
All of that is not good at all, especially calling external data source a number of time. Not all the providers are tolerant for that.
The error happens from time to time, not always.
And if you read data from the same Excel file, all works fine - no exceptions in tracing.