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Category: JSON

JSON Indexes in SQL Server 2025 CTP 2.0

Published 2025-05-20 by Kevin Feasel

Daniel Hutmacher gives it a try:

Starting today, the public preview of SQL Server 2025 is available to download!

One really interesting new feature that got my attention was the addition of JSON indexes. I’m a big fan of everything that makes working with JSON easier, since JSON blobs are so much easier to work with than table variables when you’re moving data from point A to point B. This is especially true when you’re working with complex, relational data.

Daniel lays out some of the limitations of JSON index creation and also some of the performance gains you might see from it. This will be most helpful in data engineering scenarios, shredding JSON from various services, but the normalization purist in me says that if you’re shredding JSON enough to need indexes, it’s probably time to normalize that data.

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Working with the JSON Data Type in Azure SQL DB

Published 2025-05-08 by Kevin Feasel

Dennes Torres tries out the JSON data type in Azure SQL Database:

Before this new field type, JSON data was typically stored in varchar(max) columns. There are many features to use with JSON values stored in varchar(max) columns and variables, but storing JSON as regular strings is still limited.

The built-in JSON type expands the possibilities. Using an actual JSON column, it becomes easier to build constraints related to JSON columns, for example.

Dennes also spends a lot of the article covering the JSON_ARRAYAGG() and JSON_OBJECTAGG() functions.

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Working with JSON_OBJECTAGG() and JSON_ARRAYAGG() in Azure SQL

Published 2025-02-25 by Kevin Feasel

Koen Verbeek tries out a couple of fairly new functions:

I need to construct JSON from data in our database, but I find the existing FOR JSON PATH limited when the data is not located in one single row but rather scattered over multiple rows. Is there another method on how to handle JSON data in SQL Server? Learn how to use the new SQL Server JSON Functions JSON_OBJECTAGG and JSON_ARRAYAGG in this article.

These aren’t available on-premises yet, though given that there’s a new version of SQL Server coming out in 2025, there’s a good chance we’ll have it by then.

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The JSON Data Type in Azure SQL DB

Published 2025-01-24 by Kevin Feasel

Koen Verbeeck takes a peek at what’s coming in SQL Server 2025:

We have data coming into our database from a REST API endpoint. The data is formatted as JSON documents. Is there an efficient way to handle JSON data within the SQL Server ecosystem? In this article, we look at the new JSON data types for SQL Server.

The end result is not particularly clear-cut here: reads slightly faster, writes considerably slower. There aren’t any indexes on the data type at this time, so no opportunity for improvement there.

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Storing and Parsing JSON in SQL Server

Published 2024-08-23 by Kevin Feasel

Ed Pollack talks JSON:

Like XML, JSON is an open standard storage format for data, metadata, parameters, or other unstructured or semi-structured data. Because of its heavy usage in applications today, it inevitably will make its way into databases where it will need to be stored, compressed, modified, searched, and retrieved.

Even though a relational database is not the ideal place to store and manage less structured data, application requirements can oftentimes override an “optimal” database design. There is a convenience in having JSON data close to related relational data and architecting its storage effectively from the start can save significant time and resources in the future.

Read on for plenty of examples and tips. Ideologically, I have no problem parsing JSON to load data into SQL Server. I have no real problem storing data in JSON if the calling application takes that JSON as-is and does not expect the database to modify or shred that JSON. I have no problem taking relational data and creating JSON structures to send out to calling applications. My problem comes when you store the data as JSON but then expect the database to manage data. Treat the JSON blob as atomic and we’re fine; otherwise, I want to make that data relational, as befits a relational database.

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JSON and JSONB Data Types in Postgres

Published 2024-07-11 by Kevin Feasel

Andrea Gnemmi covers a pair of data types to manage one thing:

We have all encountered the need to store non-structured or semi-structured data in an RDBMS; XML or JSON data in particular. This can be complicated, especially in the past with limited technical options, and even more complicated if we want to query this data efficiently.

Read on to learn more about the differences between JSON and JSONB, as well as mechanisms you can use to query subsets of the data.

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Emulating the FILTER Clause in Oracle

Published 2024-06-07 by Kevin Feasel

Lukas Eder notes a bit of ANSI SQL:

The following aggregate function computes the number of rows per group which satifsy the FILTER clause:

SELECT  COUNT(*) FILTER (WHEREBOOK.TITLE LIKE'A%'),  COUNT(*) FILTER (WHEREBOOK.TITLE LIKE'B%'),  ...FROMBOOK

This is useful for pivot style queries, where multiple aggregate values are computed in one go. For most basic types of aggregate function, it can be emulated simply by using CASE expressions, because standard aggregate functions ignore NULL values when aggregating. 

Lukas shows how you can also implement this logic using JSON_TRANSFORM() though I think I’d just as soon stick with COUNT(CASE WHEN BOOK.TITLE LIKE 'A%' THEN 1 END) and try hard not to think about shredding JSON.

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Avoid OPENJSON in Cursor Declarations

Published 2024-05-09 by Kevin Feasel

Joe Obbish has a public service announcement:

I found a few stored procedures with single plan cache entries over 500 MB of memory each according to sys.dm_exec_cached_plans while optimizing the plan cache in production. The stored procedures were relatively simple and both execution plans were less than 1 MB when saved as sqlplan files. I was confused, offended, and confused.

Read on to learn how this happened, see an example of it in action, and how you can avoid it in your own environment.

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SQL/JSON in Postgres

Published 2024-04-15 by Kevin Feasel

Hubert Lubaczewski makes note of some forthcoming functionality:

Back in March/April of 2022 Andres Dunstan committed a series of patches that added support for lots of really interesting features from SQL/JSON standard.

While I’m not avid user of json in database, I was very, very happy. Wrote couple of blogposts about it.

Then, around six month later they got reverted.

Lately, since last year, actually, these re-appeared again:

Read on for the list of commits and the current state of things with respect to implementing the SQL/JSON standard in Postgres.

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