Hi Knut,
Thank you very much for your reply~ I have worked around the problem by cutting a big query into small pieces. The original query is:
select meas.*
from nsc_dr1.meas meas
join nsc_dr1.object obj on obj.id=meas.objectid
where obj.ra>=3 and obj.ra<=25 and obj.dec>=-75.5 and obj.dec<=-70 and
obj.flags<4 and obj.class_star>=0.9 and obj.nphotu>=5 and meas.flags<4 and meas.filter='u'
where I try to query all the u-band single measurements in the SMC region from NSC DR1. Although, this is NOT my original purpose. At the beginning, I was planning to get all the single measurements (u, g, r, i, z, Y) for my local table. However, I realized that the crossmatch by using notebook is a bit complicated and decided just using TOPCAT to do the job. In such case, I have to download all the data in the SMC region, since the upload/crossmatch TAP service is not available.