Let me prefix this with that statement that I haven’t looked into our metadata storage implementation. But looking at the relatively frequent changes to the metadata format it seems that we should either
a) make the types for metadata records open or
b) be very careful in designing the next (and future) revision(s) of it.
I don’t know why the metadata storage was done the way it is now and what the considerations were when we did that.

Does anybody remember those (or is there even a document that contains the design and rationale)?

Thanks,
Till

On 14 Dec 2015, at 11:35, Steven Jacobs wrote:

It could easily be done as reverse-compatible, but my thinking was that this is the "wrong" choice. I can easily make the datatype dataverse an open field for the metadata. The question is, why do we have open vs closed fields for metadata at all? If it is okay for them to be open, should we get rid of the schema entirely? if it's not okay, then shouldn't this field be closed? From a design standpoint it seems that if reverse compatibility
were not an issue than the field should be closed.
Steven

On Mon, Dec 14, 2015 at 11:30 AM, Ildar Absalyamov <
[email protected]> wrote:

If fix for 2) will break the backwards-compatibility 1) might do that as
well and be submitted together.

Now 2) was a long overdue problem, I don’t think there is any reason even to try make changes backwards-compatible, because it was broken in the
first place.

On Dec 14, 2015, at 11:16, Steven Jacobs <[email protected]> wrote:

It's a new attribute, but it's a closed field, which means it isn't
backwards compatible.
Steven

On Mon, Dec 14, 2015 at 11:13 AM, Ian Maxon <[email protected]> wrote:

For 1), I guess the question is whether it would be a backwards
compatible change. Since it's just a new attribute (right?...), and it is also sort of a new feature rather than a fix for something that was critically broken, I would tend toward putting it on master. If it's
not backwards compatible though maybe it needs more careful
consideration.

-Ian

On Mon, Dec 14, 2015 at 10:12 AM, Steven Jacobs <[email protected]>
wrote:
Hi all,
I'm implementing a change so that datasets can use datatypes from
alternate
data verses (previously the type and set had to be from the same
dataverse). Unfortunately this means another change for Dataset
Metadata
(which will now store the dataverse for its type).

As such, I had a couple of questions:

1) Should this change be thrown into the release branch, as it is
another
Metadata change?

2) In implementing this change, I've been looking at the Metadata
secondary
indexes. I had a discussion with Ildar, and it seems the thread on
Metadata
secondary indexes being "hacked" has been lost. Is this also something
that
should get into the release? Is there anyone currently looking at it?

Steven


Best regards,
Ildar


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