Getting stuck on a search query using "Q3C_JOIN" along with other WHERE statements.

Question

Hi,

I'm getting stuck while trying to search using a Q3C_JOIN alongside other WHERE statements. Here is the query:

SELECT

vis.band, vis.alpha_j2000, vis.delta_j2000, vis.mag_auto, vis.number,

nisp.band, nisp.alpha_j2000, nisp.delta_j2000, nisp.mag_auto, nisp.number

FROM euclid_ero.ngc6822_vis AS vis, euclid_ero.ngc6822_nisp AS nisp

WHERE vis.alpha_j2000 BETWEEN 296.257279 AND 296.466642

AND vis.delta_j2000 BETWEEN -14.823528 AND -14.804142

AND 't' = Q3C_JOIN(nisp.alpha_j2000 , nisp.delta_j2000, vis.alpha_j2000, vis.delta_j2000, 0.000028)

When I do the query using only the Q3C_JOIN or only the limits on alpha_j2000 and delta_j2000, the query gives back results. It is when I combine them both that it gets stuck. I am trying to do the Q3C_JOIN for smaller parts of the sky, because the table gives back over the max results when not limiting anything using just Q3C_JOIN. Is there a better way of going about this?

Answer 1

The q3c functions sometimes do not work properly when using additional where clauses. See the common performance issues in the q3c documentation.

To work around this you can create a MyDB table, index it and then proceed to run the `q3c_join`. See the answer on this related question for specific syntax.