I've got the same problem, and I can just say that it depends all on the data and how complicated the where clause is.
my select statement could return 200_000 rows as maximum (maybe more), so in my case I don't have an option; I have to use LIMIT (or do a count first) otherwise these rows will cause the memory to grow too high (even before $sth->fetch* the rows take memory).

In your case, if the where clause is complicated, the query will be slow, so doing

select count(*) from table where ...;
select bla from table where ... LIMIT 100;

[download]
will be slower than select bla from table where ...;

It's probably the best to benchmark it on your table as results highly depend on your table size, data and oher things.

In reply to Re: fetch row or fetchall by tinita
in thread fetch row or fetchall by hakkr

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