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From Stephen Sprague <>
Subject Re: MAP type?
Date Thu, 15 May 2014 16:50:44 GMT
hate to bang on the json drum again but having a json_extract() function
this or any other non-scalar datatype could be implemented using a varchar

granted the syntax isn't as clean:

column['key'] vs. json_extract(column,'$.key')

but i think it gets the job done.

presto uses json_extract_scalar() and json_extract() among others. cf.  This could be used as
a guide, perhaps.

On Wed, May 14, 2014 at 2:30 PM, Rob Roland <> wrote:

> Hi all,
> I have a use-case that would benefit well from a MAP type, similar to how
> Hive uses a map. I'd like to avoid using a JOIN, due to the amount of rows
> on each side of the JOIN. In Hive's case, you would assign a column family
> to the MAP field.
> Essentially, I have an entity that I want to add quite a bit of dynamic
> data that would be unknown at both initial query time and query time. A
> contrived example is below:
> I'd like to do something like this:
> CREATE TABLE facebook_post (
> post_body VARCHAR,
>  bitly_links MAP<VARCHAR, VARCHAR>
> );
> SELECT * FROM facebook_post;
> As opposed to:
> CREATE TABLE facebook_post (
> post_body VARCHAR
> );
> CREATE TABLE facebook_post_links (
> facebook_post_id VARCHAR,
> bitly_id VARCHAR,
> expanded_link VARCHAR,
>  CONSTRAINT pk PRIMARY KEY (facebook_post_id, bitly_id)
> );
> SELECT * FROM facebook_post AS fp
> LEFT OUTER JOIN facebook_post_links AS fpl ON (fpl.facebook_post_id =
> I realize that a MAP type is outside of the SQL standard, but it would be
> excellent in my use-case. I could accomplish this with an ARRAY type, but
> the expansion of links happens as a post-processing step, and
> would probably involve locking, as appending to an ARRAY has to happen
> client-side.
> I'd be willing to take a shot at making a MAP type, but I would want to
> make sure this change would be welcomed into mainline Phoenix before
> embarking on something like this.
> Thanks,
> Rob Roland

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