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could you check it please? thanks~
asked Mar 14, 2019 by anonymous | 172 views

1 Answer

0 votes
Hi there,

So this is likely happening because the size of the returned result is exceeding the memory available to the service that packages the result.  The service crashes, so the HTTP request returns a failure.  We are looking at ways to  address the root problem.  In the meantime, can you please:

1. Identify who you are so that we can work with you to design a query that will run successfully

2.  Tell us what query you are trying to run (we think we know the submitted query that caused the crash, but would be good to know directly from you).


Knut Olsen
answered Mar 15, 2019 by kolsen (2,700 points)
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.
Hi deepeyesym,

Ok, cutting the query into smaller pieces is a good approach.

If the crossmatch notebook seems too complex, have you had a look at the crossmatch web interface (https://datalab.noao.edu/xmatch.php)?  You could upload your table and crossmatch against nsc_dr1.object, then join that result against nsc_dr1.meas to retrieve the single epochs.
Hi Knut,
    I have already tried that before. However, due to the large amount of single epochs data (i have about 38900 targets), the query is always expired in 300s........thanks anyway~

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