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Re: The future of Dynamic Columns


Hi, Tom!

On Jan 27, Tom Worster wrote:
>  2. In at least two places (one was here
> <https://mariadb.com/kb/en/mariadb/indexoptimizations-in-dynamic-columns/>)
>  I've read text with the implied meaning, "we may improve such-and-such
> about MDC if and when people start actually using it."

While I know that there are users of dynamic columns, I don't remember
seeing any feature requests for them.

Okay, there was one, for JSON-like arrays, but it depends on having
array as a data type, like in regular columns. Not a standalone feature
for dynamic columns that we can just go no and implement.

>   3. The MDC syntax is so clunky I worry that people who might find it
> useful are turned away.

That could as well be. And it's bad. What is worse - they're turned away
without complaining so we don't know what to do to fix dynamic columns.

Any suggestions how we can make the syntax less clunky?

>   4. Did the 5.3 version with numbers for column names turn people off
>   MDC for good?

As far as I have heard, those people who wanted dynamic columns in the
firts place found the implementation with numbers quite sufficient for
their needs. But new users probably didn't, I know :)

>   5. The requirement to specify datatype when querying a dynamic column is
> agonizing. The manual says it is a limitation of SQL itself (presumably
> immutable) but PostgreSQL manages to avoid it when querying jsonb doc
> properties.

We could workaround this requirement by assuming everything is a string,
for example. This can be implemented, if that's what users want.

>   6. The lack of indexing of dynamic columns is a severe limitation but
> PostgreSQL manages to index jsonb document properties.

Right, I know. We've heard this feature request a few times already.
That's why - no promises! - this feature is currently being discussed
for 10.2.

>   7. I head a rumor that some kind of JSON features are coming to Maria.

I wonder what exactly you've heard and where :)
There are many different ways of implementing "JSON features", some of
them actually use dynamic columns as the underlying storage format.

Currently there is no well defined JSON task in mariadb.org/jira,
so nobody knows what exactly will be implemented yet.

But now is the time to affect the 10.2 roadmap. What "JSON features"
would you like to see in MariaDB?


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