Azure SQL & SQL Server 2016 JSON

Azure SQL & SQL Server JSON DAVIDE MAURI INFO@DAVIDEMAURI.IT - @MAURIDB HTTP://SPEAKERSCORE.COM/WP5Z

About Me Microsoft Data Platform MVP since 2006 Works with SQL Server from 6.5, on BI from 2003 Specialized in Data Solution Architecture, Database Design, Performance Tuning, High-Performance Data Warehousing, BI, Big Data Very strong developer background Loves community! ◦ President of UGISS (Italian SQL Server UG) for 11 Years ◦ AppDev VG Leader since 2017 Regular Speaker @ SQL Server events Director SW & Cloud @ Sensoria: http://www.sensoriafitness.com/ E-mail: info@davidemauri.it -Twitter: @mauridb Blog: 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 JSON is everyone… …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

JSON and SQL Server No support until SQL Server 2016 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-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 path handling ◦ LAX: null ◦ STRICT: error $.conference.speaker $.conference.speaker.editions[0]

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

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

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: 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

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)

JSON & Stored Procedures Perfect to pass an object ◦ Dev happy because they can just pass an object ◦ DBA happy because: ◦ No SQL-Injection problems ◦ Can use the passed object as json or a relational object as they wish ◦ Everyone’s happy ◦ Easy to pass arrays of objects ◦ Easy to create UPSERT procedures (everyone really LOVE this) ◦ But keep in mind that BULK INSERT is still the way to got to bulk load data (say when you have 10000 or more rows to insert) ◦ Performances are great!

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

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- node-js-to-SQL-Server JSON is also supported on SQL Azure ◦ Requires server version V12 ◦ Right now (2017) has *less* limitations than SQL Server 2016

Last things Works *incredibly well* with columnstore ◦ Up to 25x data compression ◦ SQL Server vNext e SQL Azure only ◦ https://blogs.msdn.microsoft.com/sqlserverstorageengine/2017/02/09/extre me-25x-compression-of-json-data-using-clustered-columnstore-indexes/

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/

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

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

Demos available on GitHub HTTPS://GITHUB.COM/YOREK/SQLSAT613

Azure SQL & SQL Server 2016 JSON

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