I do note that the sql query listed in OP of this bug contains calls to artefact_attachment and artefact_access_role, which can be misisng the correct indexing/keys if upgraded from mahara 1.0 (see bug 1081947).
On saying that it - this problem may not due to that issue so adjusting the SQL_BIG_SELECTS to equal 1 may still need to be done.
I do note that the sql query listed in OP of this bug contains calls to artefact_attachment and artefact_ access_ role, which can be misisng the correct indexing/keys if upgraded from mahara 1.0 (see bug 1081947).
On saying that it - this problem may not due to that issue so adjusting the SQL_BIG_SELECTS to equal 1 may still need to be done.