(r1) ADQLVectorMath < IVOA

IVOA Web>IvoaDAL>ADQL>ADQLVectorMath (revision 1) (raw view)~~EditAttach~~

---+ A proposal for vector math in ADQL

With tables containing massive amounts of vectors (e.g., the collections of low-resolution spectra within Gaia DR3 or the Digitised Byurakan Surveys), giving TAP users a toolset to do server-side work with arrays becomes highly desirable and will significantly enhance the power of ADQL to do server-side analyses. This is an attempt to provide a baseline feature set for that.

TAP servers supporting this should declare that by defining a language feature. While no IVOA specification exists for array operations, use the VECTORMATH key from GAVO's ADQL extensions standards record, like this:

<pre>&lt;languageFeatures type="ivo://org.gavo.dc/std/exts#extra-adql-keywords"&gt;
  &lt;feature&gt;
    &lt;form&gt;VECTORMATH&lt;/form&gt;
      &lt;description&gt;You can compute with vectors here. See
        https://wiki.ivoa.net/twiki/bin/view/IVOA/ADQLVectorMath
        for an overview of the functions and operators available.
      &lt;/description&gt;
   &lt;/feature&gt;
&lt;/languageFeatures&gt;
</pre>

---++ Basic Math

   * vec1+vec2 is the component-wise sum of two vectors. Where vec1 and vec2 have unequal length, the result is padded with NULLs to the length of the longer vector.
   * vec1-vec2 is the component-wise difference of two vectors. Where vec1 and vec2 have unequal length, the result is padded with NULLs to the length of the longer vector.
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Topic revision: r1 - 2022-06-30 - MarkusDemleitner

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