Data lineage is one of those concepts that sounds more complicated than it is. Once you understand the basic idea, it’s actually pretty intuitive. And it solves a problem that anyone who works with data has run into.
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What is a Data Lake?
Data lake is one of those terms that gets thrown around a lot in conversations about data strategy, often alongside data warehouses and data marts. But what actually is a data lake, and how does it fit into the picture? Let’s find out.
JSON_OBJECTAGG() in SQL Server 2025: Build JSON Objects Straight from Your Queries
SQL Server 2025 ships with a handful of genuinely useful additions, and JSON_OBJECTAGG() is one of the better ones. It lets you aggregate rows into a single JSON object (with key-value pairs pulled directly from your data) without any string hacking or FOR JSON PATH gymnastics.
Here’s what it does, how it works, and when you might actually use it.
What Is ELT?
Data doesn’t always arrive clean, structured, or ready to use. And anyone who’s worked with data knows that gap between raw information and actionable insight is where a lot of the real work happens. ELT is a modern approach to bridging that gap.
Unlike its older cousin ETL, ELT flips the script by loading data into its destination first and transforming it there, taking advantage of the processing power that today’s cloud data warehouses have in abundance. The result is a faster, more flexible pipeline that’s become something of a default choice for many data teams building on platforms like Snowflake, BigQuery, or Redshift.
What is ETL?
If you’ve spent any time around data teams or analytics tools, you’ve probably heard the term ETL thrown around. It sounds technical, but the concept is actually pretty straightforward. This article looks at what the term actually means, how it works, and why it matters.
What Is a Time Series Database?
A time series database (TSDB) is a database built specifically to store and query data that’s tied to timestamps. This could include things like sensor readings, stock prices, server metrics, or IoT data. Basically anything where the when is just as important as the what.
Standard relational databases can technically store this kind of data, but they weren’t designed for it. Time series databases are optimized from the ground up for time-ordered data, which means they’re faster, more efficient, and more practical for time-heavy workloads.
JSON Indexes in SQL Server 2025
Before SQL Server 2025, indexing JSON data meant creating a computed column to extract the value you cared about, then indexing that column. It works, and it’s still a solid approach, but it requires you to know upfront which paths you’ll query, maintain separate columns for each one, and keep those columns in sync with any schema changes. SQL Server 2025 introduces JSON indexes as a native alternative. It’s a single index structure that covers the JSON column directly, without the computed column overhead.
JSON indexes are currently in preview and only available in SQL Server 2025 on-premises. They aren’t available yet on Azure SQL Database, Managed Instance, or Fabric. That said, things could be different by the time you read this article.
What is a Serverless Database?
In the context of cloud databases, a serverless database is one that automatically manages all server resources for you, including scaling up and down based on actual usage, even scaling to zero when not in use. Unlike traditional databases where you provision specific server capacity upfront, serverless databases dynamically allocate resources as needed and charge you only for what you actually consume.
The term “serverless” doesn’t mean there are no servers involved. Servers still exist, but you don’t have to think about them. The cloud provider handles all capacity planning, scaling, and infrastructure management automatically in the background.
What Is a Composite Constraint?
A composite constraint is a database constraint that applies to two or more columns together, rather than to a single column on its own.
The most common usage is on primary keys, but composite constraints also show up as unique constraints, foreign keys, and check constraints spanning multiple columns.
Understanding JSON_CONTAINS() in SQL Server 2025
JSON_CONTAINS() is a new function introduced in SQL Server 2025 that lets you check whether a value exists at a specific path in a JSON document. It returns an integer. This is 1 if the value is found, 0 if not, and NULL if any argument is null or the path doesn’t exist. That makes it a natural fit for WHERE clauses when you’re filtering rows based on JSON content.
It’s currently in preview (although this will almost certainly change soon) and only available from SQL Server 2025.