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From Michael Mior <mm...@uwaterloo.ca>
Subject Re: Materialized view rewriting
Date Wed, 24 Feb 2016 22:27:49 GMT
I expected as much re: code documentation. Totally understandable, but I
figured it couldn't hurt to check.

As for Cassandra and materialized views, that's exactly what I was thinking
and the reason I opened the issue about updates to support Cassandra 3.x :)
Calcite's automatic rewriting seems to work as expected when the
materializations are manually defined. I'd like to see if I can get the
adapter to automatically pull in materialized view definitions from
Cassandra. Since CQL and SQL are so similar, I'm hoping it won't be too
much of a challenge to have Calcite use the CQL definitions of the
materialized views.

--
Michael Mior
mmior@uwaterloo.ca

2016-02-24 17:22 GMT-05:00 Julian Hyde <jhyde@apache.org>:

> By the way, interesting that you are interested in Cassandra and
> materialized views. Cassandra announced materialized view support
> recently[1] but they solved only half of a problem (not an
> insignificant half, I hasten to add), namely materialized view
> maintenance. They don't transparently substitute them into the query -
> you have to reference the materialized view explicitly in y our query
> - so in my book they've not delivered materialized view support. If
> you're planning to deliver REAL materialized view support to Cassandra
> that would be awesome.
>
> Julian
>
> [1]
> http://www.datastax.com/dev/blog/new-in-cassandra-3-0-materialized-views
>
>
> On Wed, Feb 24, 2016 at 2:17 PM, Julian Hyde <jhyde@apache.org> wrote:
> > As is typical for complex pieces of code like this, the documentation
> > is in the code (and the unit test). It's probably not what you wanted
> > to hear, but the code mutates quite fast and so if we'd written a
> > design doc a few months ago it would be partially inaccurate.
> >
> > I, Maryann Xue and Amogh Margoor are the main authors of this code.
> >
> > Suggest you find a relevant test case in MaterializationTest (or write
> > a new one) and run it with trace enabled and/or in a debugger. You
> > will see the process of matching an expression to a MV bottom up if
> > you watch each call to UnifyRule.unify.
> >
> > Julian
> >
> >
> > On Wed, Feb 24, 2016 at 1:40 PM, Michael Mior <mmior@uwaterloo.ca>
> wrote:
> >> Is there any documentation anywhere on how the current implementation of
> >> query rewriting for materialized views work? Mostly I'm referring
> >> to MaterializedViewSubstitutionVisitor. There's a lot of code to digest
> >> with not a lot of documentation and it would be helpful to have a
> reference
> >> to refer. Thanks!
> >>
> >> Cheers,
> >> --
> >> Michael Mior
> >> mmior@uwaterloo.ca
>

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