Negative SDSS objIds?

Question

For some reason some objIds in cross-match tables for SDSS are negative, which does not make sense. Is it a bug?

An example:

select * from  ls_dr8.x1p5__tractor_primary_n__sdss_dr16__specobj where id1= 8797213156704970

Answer 1

This is not a bug, but a consequence of the integer representation.  The specObjID values in Data Lab tables are cast as signed integers, because this is what the database supports.  However, some specObjID values are larger than 2⁶³, therefore these will be negative in a signed representation.

If you need to work with unsigned values of specObjID, you will have to use a more advanced query interface, such as the Data Lab query client.

Comments

Pity that this is a DB limitation. Can't you store specObjID as a string in that case? It is a bit inconvenient to use these data in combination with external SDSS tables, when IDs do not match...

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As I mentioned, if you need to work with unsigned values of specObjID, you certainly can, you will have to use a more advanced query interface, such as the Data Lab query client.  Is that what you are specifically asking for here?