Re: SQLJSON - Mailing list pgsql-jdbc

Then why starting a discussion about SQLJSON? ;-)

 

From: davecramer@gmail.com [mailto:davecramer@gmail.com] On Behalf Of Dave Cramer
Sent: Samstag, 27. Juni 2015 13:12
To: Markus KARG
Subject: Re: [JDBC] SQLJSON

 

 

On 27 June 2015 at 03:12, Markus KARG <markus@headcrashing.eu> wrote:

Please read this regarding pluggability:
https://json-processing-spec.java.net/nonav/releases/1.0/fcs/javadocs/javax/
json/spi/JsonProvider.html.

Please read this regarding inability to agree on a standard:
https://jcp.org/en/jsr/results?id=5486.

The merits of adding a SQLJSON type to JDBC would be that in case an RDBMS
might have some kind of special support for high-performance object-tree
transmission in the network protocol (like lazy lookup and delayed
transmission of child objects for example, or using binary transmission
instead of JSONP plain-text), the driver could make use of that knowledge
and work in the fastest and memory-saving way. That benefits are impossible
to gain when using a character stream, as that requires to explicitly
inflate to a full JSONP representation in-memory just to parse that string
in turn in a second step.

Unfortunately none of the above is currently possible in PostgreSQL

 

Dave Cramer

dave.cramer(at)credativ(dot)ca
http://www.credativ.ca

-----Original Message-----
From: pgsql-jdbc-owner@postgresql.org
[mailto:pgsql-jdbc-owner@postgresql.org] On Behalf Of Steven Schlansker
Sent: Freitag, 26. Juni 2015 19:29
To: Dave Cramer
Cc: List
Subject: Re: [JDBC] SQLJSON


On Jun 26, 2015, at 10:23 AM, Dave Cramer <davecramer@gmail.com> wrote:

>
> On 26 June 2015 at 13:01, Steven Schlansker <stevenschlansker@gmail.com>
wrote:
>
> On Jun 26, 2015, at 7:57 AM, Dave Cramer <davecramer@gmail.com> wrote:
>
> > I'm looking for comments on how to implement a SQLJSON type in JDBC.
> >
> > As there is no getSQLJSON in the resultset interface this could only be
used in getObject.
> >
> > Notionally it would model itself after SQLXML.
> > https://docs.oracle.com/javase/7/docs/api/index.html?java/sql/SQLXML
> > .html
>
> I used JSON extensively in one of my projects, but have never used SQLXML.
I'm having trouble understanding why the SQLXML interface adds any value to
passing rs.getBinaryStream to your favorite JSON parser.  Especially since
you would have to use getObject, I am not seeing how:
>
> rs.getObject("field", SQLJSON.class).mapToType(MyType.class)
>
> is simpler than:
> jacksonObjectMapper.readValue(rs.getBinaryStream("field"),
> MyType.class)
>
> which already works today as far as I understand.  Doubly so since nobody
will agree on which JSON parsing library to use.
>
> I'm sure I'm missing something?
>
>
> I don't think you are; as you rightly pointed out now we would have to
> add a json parser to the driver, which I'm reluctant to do
>

If this feature is developed, I think the JSON parser should be pluggable
and optional if possible.  Then users that do not want it do not need to
drag in a large dependency.

That said, without a more convincing use case or a compelling API that we
could easily add, I don't see this interface being "worth its weight" as an
addition.

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