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https://issues.apache.org/jira/browse/CASSANDRA-7970?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14300120#comment-14300120
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Robert Stupp commented on CASSANDRA-7970:
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I took a short look at the patch and played around a little bit with this.
Some comments:
* A test with null values in {{testFromJsonFct()}} and {{testToJsonFct()}}
would be nice (toJson handles null correctly, fromJson throws an NPE for
{{INSERT INTO tojson (k, asciival ) VALUES ( 0, fromJson(null) );}})
* Can you add a {{INSERT JSON}} variant that tackles tuples and types?
* I tried {{insert into some_table (k, asciival ) JSON \{"k": 0, "asciival":
"foobar"\};}} in cqlsh - it complains with a syntax error (obviously my bad).
Was wondering if we really need to mention the column names since they are
contained in the JSON. Couldn't a {{insert into some_table JSON ?;}} with json
{{"\{"k": 0, "asciival": "foobar"\}"}} also work?
* The Java Driver tries to contact a coordinator that owns the target
partition. This gets complicated with {{INSERT JSON}} since the driver would
have to parse the JSON before it actually knows the "correct" node. Maybe we
can discuss a follow-up that both allows {{VALUES}} and {{JSON}} - e.g.
{{INSERT INTO some_table (partitionKey, clusteringKey) VALUES (1, 2) JSON ?}},
where the {{JSON ?}} part contains more columns.
* missing license header in {{Json.java}}
* In {{FunctionCall}} you exchanged „fun“ with „fun.name()“ eliminating the
function signature in the exception message
* {{Selection.rowToJson}} : use Collections.singleton instead of
{{Arrays.asList}}
* {{Selection.rowToJson}} : would be nicer (and eliminate one String instance)
to replace sb.append(JSONValue.escape(columnName)) with something like
JSONValue.escape(columnName, sb); (make escape write to sb)
* Similar for {{AbstractType.toJSONString}} - let the implementation write to
the string builder
* {{ReversedType}} : not sure whether the impl is correct - doesn’t it need to
reverse the binary representation?
* {{FromJsonFct}} + {{ToJsonFct}} : would be nicer to have a CHM instead of
synchronized HashMap. Also these maps in these classes have {{AbstractType}} as
the key and are never evicted - means: a changed user type would remain forever
in these maps and if a UDT. This might get irrelevant when {{AbstractType}} is
removed - so not sure, whether we should fix this now - maybe open a
follow-up-ticket for this? A simple fix would be to 'statically cache' function
instances for primitive types but always create a new instance of these
functions for tuples + UDTs ; then you could pre-create the function instances
completely eliminating the need for CHM or synchronized.
Altogether: really nice work :)
> JSON support for CQL
> --------------------
>
> Key: CASSANDRA-7970
> URL: https://issues.apache.org/jira/browse/CASSANDRA-7970
> Project: Cassandra
> Issue Type: New Feature
> Components: API
> Reporter: Jonathan Ellis
> Assignee: Tyler Hobbs
> Fix For: 3.0
>
> Attachments: 7970-trunk-v1.txt
>
>
> JSON is popular enough that not supporting it is becoming a competitive
> weakness. We can add JSON support in a way that is compatible with our
> performance goals by *mapping* JSON to an existing schema: one JSON documents
> maps to one CQL row.
> Thus, it is NOT a goal to support schemaless documents, which is a misfeature
> [1] [2] [3]. Rather, it is to allow a convenient way to easily turn a JSON
> document from a service or a user into a CQL row, with all the validation
> that entails.
> Since we are not looking to support schemaless documents, we will not be
> adding a JSON data type (CASSANDRA-6833) a la postgresql. Rather, we will
> map the JSON to UDT, collections, and primitive CQL types.
> Here's how this might look:
> {code}
> CREATE TYPE address (
> street text,
> city text,
> zip_code int,
> phones set<text>
> );
> CREATE TABLE users (
> id uuid PRIMARY KEY,
> name text,
> addresses map<text, address>
> );
> INSERT INTO users JSON
> {‘id’: 4b856557-7153,
> ‘name’: ‘jbellis’,
> ‘address’: {“home”: {“street”: “123 Cassandra Dr”,
> “city”: “Austin”,
> “zip_code”: 78747,
> “phones”: [2101234567]}}};
> SELECT JSON id, address FROM users;
> {code}
> (We would also want to_json and from_json functions to allow mapping a single
> column's worth of data. These would not require extra syntax.)
> [1] http://rustyrazorblade.com/2014/07/the-myth-of-schema-less/
> [2] https://blog.compose.io/schema-less-is-usually-a-lie/
> [3] http://dl.acm.org/citation.cfm?id=2481247
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