Gaia Archive arrays implementation

[Mark Taylor]

Juan Carlos,

On Mon, 21 Aug 2017, Juan Carlos Segovia wrote:

> This mail is to explain how arrays are going to be handled in the Gaia archive
> TAP service for DR2.

thanks for summarising this here.  IMHO what you've outlined sounds
reasonable until TAP 1.1 is more stable and supported.

One point:

> SELECT get_double_array_element('{{1.0,2.6},{0.8,0.1}}','[1][2]') from

Have you considered a  more straightforward syntax like

   get_double_array_element('{{1.0,2.6},{0.8,0.1}}', 1, 2)

which could be overloaded with variable numbers of integer index
arguments like:

   get_double_array_element('{1.0,2.6}', 1)

The string syntax is more unwieldy to use, especially if you want
to index with a variable, and also in view of the fact that as I
understand it most of the arrays in this DB will be 1-dimensional
(Alcione's comment in C9GACS-235 "No other two index arrays in DR2
(to my knowledge)" [apart from the 6x6 form of the covariance]).

But, this is an implementation detail so if ESDC want to do it that
way it's up to you.

Mark

--
Mark Taylor   Astronomical Programmer   Physics, Bristol University, UK
m.b.taylor at bris.ac.uk +44-117-9288776  http://www.star.bris.ac.uk/~mbt/