Hi Bruno.
Welkome to thé odk community.
You will need to make use of search() options such as startswith() or contains().
We use it to filter matching lines into 400000 species name.
For the moment the documentation page is not complete ans you'll find the description of those options here : Looking for an old documentation page about search() function
"search(csvName, 'startswith', columnsToSearch, searchText)": This search expression includes all distinct rows that start with the specified text in the specified column(s) (e.g., "search('hhplotdata', 'startswith', 'respondentname', ${nameprefix})"). The third parameter specifies either a single column name to search, or a comma-separated list of column names to search. Rows with matches in any specified column will be included."