TAP RFC [MTIME]

[Douglas Tody]

On Thu, 17 Sep 2009, Gerard wrote:

> I agree with Pat and Francois, MTIME can be covered using standard DB
> implementations, no need for a special key word.

This could work for most of what MTIME provides so long as we can
agree upon the necessary metadata.  The main issue is what to do about
deleted table rows.  To maintain a remote replica of a table we need
to know when a row is deleted, not only when it has been updated or
inserted.  The MTIME proposal supported this without mandating that a
specific technique be used on the DBMS side as it can get complicated.

> Extrapolating on Francois'
> comment, I would propose to remove the "primary" attribute from the column
> metadata? When I do a

Unfortunately this would prevent switching between the "narrow" and
"wide" views of a table on the client side in smart table viewers.
This is a popular feature for viewing astronomical catalogs and other
tables which can have a lot of columns.  In previous discussions
we considered using only views but the consensus at the time was to
provide a simpler mechanism (the "primary" flag) for this most basic
narrow/wide use case, providing a view mechanism as well to allow
the data provider to define additional custom views of the data.
It is a simple enough thing to support in the column metadata which
does not take anything away.

 	- Doug