Disabling indices while other app is using the database - dangerous?

[Jan Doggen]

Hi everyone,

we're running dynamic queries that only read data like:

CREATE QUERY dyn-query.

dyn-query:SET-BUFFERS(table-name).

dyn-query:QUERY-PREPARE('FOR EACH ' + cTabelnaam).
dyn-query:QUERY-OPEN.

dyn-query:GET-FIRST.
iTbNumFields = table-name:NUM-FIELDS.
REPEAT WHILE NOT dyn-query:QUERY-OFF-END:
DO iNumVeld = 1 TO iTbNumFields:
hVeld = table-name:BUFFER-FIELD(iNumVeld).

I read in the Performance FAQ that disabling indices may speed up things.
Will this also help in queries like the above (we don't nee to get the data
in any specific order), and more importantly:

Can we do this safely with another app accessing the database at the same time
(and *that* app is not just reading).

Thanks in advance,
Jan