SQL Server 2016 JSON

SQL Server 2016 JSON

Davide Mauri

Join the conversation on Twitter: @DevWeek // #DW2016 // #DevWeek


About MeMicrosoft SQL Server MVPWorks with SQL Server from 6.5, on BI from 2003Specialized in Data Solution Architecture, Database Design, Performance Tuning, High-Performance Data Warehousing, BI, Big DataPresident of UGISS (Italian SQL Server UG)Regular Speaker @ SQL Server eventsConsulting & Training, Mentor @ SolidQE-mail: [email protected]: @mauridb Blog: http://sqlblog.com/blogs/davide_mauri/default.aspx

mailto:[email protected]

http://sqlblog.com/blogs/davide_mauri/default.aspx


Agenda• JSON in life• JSON and SQL Server

• JSON “Datatype” (not really) • Navigation via “dot” notation• LAX and STRICT path modes

• JSON Functions• JSON_VALUE, JSON_QUERY, JSON_MODIFY, ISJSON

• JSON & SQL• OPENJSON• FOR JSON• Indexes

• The Dynamic Schema problem (or “the Relational Division”)


JSON in Life• That’s a DEV conference….• …so I’m sure you know JSON pretty well • For who doesn’t already know it:

• JavaScript Object Notation• Simple, Human-Readable, Text data format• Based on Key-Value pair idea

• Values can be: Scalar, Arrays, Key-Value pairs• No strict schema (yet)• Supported in any language, cross platform• De-facto standard

• http://www.ietf.org/rfc/rfc4627.txt Image taken from wikipedia

http://www.ietf.org/rfc/rfc4627.txt


JSON and SQL Server• No support until SQL Server2016• Before SQL Server 2016:

• One option is to use SQLCLR• Solutions available surfing the web:• http://www.sqlservercentral.com/articles/SQLCLR/74160/ • http://www.json4sql.com/examples.html

• Another (more limited) option is a pure T-SQL solution• https://www.simple-talk.com/sql/t-sql-programming/consuming-json-strings-in-sql-serv

er/

http://www.sqlservercentral.com/articles/SQLCLR/74160/

http://www.json4sql.com/examples.html

https://www.simple-talk.com/sql/t-sql-programming/consuming-json-strings-in-sql-server/

https://www.simple-talk.com/sql/t-sql-programming/consuming-json-strings-in-sql-server/


JSON and SQL Server• Why native JSON support it’s important?

• Simplify application development• Especially in non-MS environments, since JSON is *very* well supported (eg. Python / JS)

• Reduces the impedance mismatch between app and db• Make schema extensibility a breeze

• But without having *only* “liquid” schemas. Schema is a good thing in general. Having the option to decide when and when not use it is a key feature today:


JSON and SQL Server 2016• Native support to JSON• No specific datatype format (like XML)

• relies on varchar(max)

• Specific function to • manipulate and create JSON• extract data from JSON• turn relational data into JSON and vice-versa


JSON Path• The dollar sign ($) represents the context item.• The property path is a set of path steps.

• Key names. • Array elements. Arrays are zero-based.• The dot operator (.) indicates a member

of an object.

• “LAX” or “STRICT” option set invalid pathhandling

• LAX: null• STRICT: error

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JSON Path• Like XPATH but for JSON

• http://goessner.net/articles/JsonPath• https://jsonpath.curiousconcept.com• http://jsonpath.com

• SQL Server 2016 doesn’t offer a full support yet.

• Is a subset of JSONPath

http://goessner.net/articles/JsonPath/

https://jsonpath.curiousconcept.com/

http://jsonpath.com/


JSON Functions• Scalar functions to manage JSON data

• ISJSON: test if string is JSON• JSON_VALUE: extract a scalar value• JSON_QUERY: extract a JSON value• JSON_MODIFY: modify a JSON property


DEMOSQL/JSON First Contacts


JSON Functions• Tabular functions

• OPENJSON: turn a JSON object into a table• FOR JSON: turn a table into a JSON object


OPENJSON• Support both implicit and explicit schema:

IMPLIC

ITEXPLICIT

Type Meaning

0 null

1 string

2 int

3 true/false

4 array

5 object


OPENJSON• Very useful with OPENROWSET to import JSON


FOR JSON• Two modes: AUTO, PATH

• AUTO: shape of JSON using the SELECT statement as guideline

• PATH: column alias and JSON_QUERY function allows for total control of final JSON


DEMOJSON and Relations


JSON Indexes• JSON data support indexes…even if it doesn’t seems so!

• Right, there is no special index like it happens with XML

• How to index JSON Data• Create calculated columns for scalar JSON values you know if want to index• Create FULLTEXT index to index whole JSON document• Use the FULLTEXT index to perform “near” term search

• CONTAINS(JSON_DATA, ‘NEAR((“Key”, “Value”),1)’)• Uses a “Generalized Inverted Index” (like Postgres)

• https://msdn.microsoft.com/en-us/library/cc879306.aspx

• Indexes to support JSON Path queries (like XML) are not yet there• You have to DIY here (Service Broker to async update EAV table)

https://msdn.microsoft.com/en-us/library/cc879306.aspx


DEMOJSON Indexing


Dynamic Schema• JSON sounds like a perfect solution of all the “Dynamic Schema”

situations• Why “Dynamic Schema” and not Schemaless?

• Because schemaless does not *really* exists! In reality a schema always exists, albeit implicit, otherwise it would be impossible to handle data


Implict Schema

Any data that doesn't fit this implicit schema will not be manipulated properly, leading to errors.

(Schemaless data structures, Martin Fowler)


Words of Wisdom

«Schemaless => implicit schema = bad. Prefer an explicit schema»

(Schemaless data structures, Martin Fowler)


Dynamic Schema• What if my use case is one that perfectly fits the need for a implicit

schema?• The only possible solution are the so-called «No-SQL» databases

• Document Database or Key-Value store?• How can I integrate it into already existing database?• Integration does not come for free!

• Now with SQL Server 2016 we have an additional option! • No integration problems, No added complexity• Great Performances• Works within a well-known platform


DEMODynamic Schema


Last things• JSON and the new COMPRESS function works well together:

• Compress using GZIP algorithm (Natively supported by browsers)• Simplify app development and integration with rdbms• Sample usage with node.js• http://www.codeproject.com/Articles/1063475/Pushing-Compression-from-n

ode-js-to-SQL-Server

• JSON is also supported on SQL Azure• Requires server version V12

http://www.codeproject.com/Articles/1063475/Pushing-Compression-from-node-js-to-SQL-Server

http://www.codeproject.com/Articles/1063475/Pushing-Compression-from-node-js-to-SQL-Server


Conclusions• JSON does not substitute relational solutions

• Can be useful to extend them• Can be *very* useful to simplify app-to-db communications

• JSON as parameter value! That’s a dream • FAQ:

• https://msdn.microsoft.com/en-us/library/mt631706.aspx

• Follow SQL Server JSON PM:• https://blogs.msdn.microsoft.com/sqlserverstorageengine/tag/json

https://msdn.microsoft.com/en-us/library/mt631706.aspx

https://blogs.msdn.microsoft.com/sqlserverstorageengine/tag/json


Help us to make JSON support better!• Don't restrict JSON_VALUE and JSON_QUERY to string literals only

for the path• https://connect.microsoft.com/SQLServer/Feedback/Details/2235470

• Support JSON in COLUMNSET for SPARSE columns• https://connect.microsoft.com/SQLServer/feedback/details/2533991

https://connect.microsoft.com/SQLServer/Feedback/Details/2235470

https://connect.microsoft.com/SQLServer/feedback/details/2533991


Help us to make JSON support better!• Allow support for JSON of simple arrays generation

• https://connect.microsoft.com/SQLServer/Feedback/Details/1383569

• JSON_VALUE: adding another optional parameter, which defines what type of value the function will return

• https://connect.microsoft.com/SQLServer/Feedback/Details/2543881




Thanks!Questions?


Demos available on GitHubhttps://github.com/yorek/devweek2016

https://github.com/yorek/devweek2016

SQL Server 2016 JSON

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