Detect new sales using INDEX/MATCH very slow

Bob phillips, you are my savior today,
that worked the charm. Thanks very much

I was reluctant to use index/match because of how slow it is in another spread sheet I created to keep track of CD sales at concerts.
I attached the file to give you an idea if you have time and curiosity to take a look.

the function that seems to be so slow is the following:
=IFERROR(INDEX(vente!B:B, MATCH(0,COUNTIF($A$1:A1, vente!B:B), 0)),"")
and it's located in the 'total' sheet column A.

It's purpose is :
_to automatically detected when there are news sales in the "vente" sheet,
_create a cell with the name of the event, so that the other cells in the row can fill automatically

If you (or anyone else reading this) have any suggestions on how to better deal with this purpose so that it's not so slow, I would greatly appreciate it.

thanks again!!

hello TMS and canapone,
thanks very much for your answers.
If seems that both work but I don't understand why for canapone's solution, i don't need to use control+shift+enter when I'm still using an index function?
in other words why do we need to use control+shift+enter here:
=IFERROR(INDEX(quievent, MATCH(0,COUNTIF($A$1:A10, quievent), 0)),"")

and not here:
=IFERROR(INDEX(quievent,MATCH(0,INDEX(COUNTIF($A$1:A25,quievent),), 0)),"")

thanks again so much for your replies as it has sped up my spread sheet about 500%