> ## Documentation Index
> Fetch the complete documentation index at: https://docs.nekt.com/llms.txt
> Use this file to discover all available pages before exploring further.

# What are Delta Tables?

> Explore the power of Delta Tables for structured data management and version control.

### What are Delta Tables?

Delta Tables are a modern data storage format that combine the scalability of data lakes with the reliability of data warehouses. They offer powerful features like **version control**, **schema enforcement**, **time travel**, and **ACID transactions**, making them ideal for everything from analytics to machine learning.

In Nekt, **Delta Tables are automatically applied to data in the Raw Layer**, giving your data a structured and scalable foundation from the moment it enters the platform.

***

### Why Use Delta Tables?

Delta Tables address many of the challenges of traditional data storage formats by offering:

* **Version Control**\
  Track changes and access historical versions of your data at any time.

* **Schema Enforcement**\
  Protect data integrity with structure-aware write operations.

* **Data Lineage**\
  Automatically log every change for full transparency and governance.

* **Efficient Querying**\
  Optimize performance for large-scale analytics and ML workloads.

* **ACID Transactions**\
  Ensure data consistency, even in concurrent and complex workflows.

***

### How Delta Tables Work in Nekt

In Nekt, Delta Tables are applied automatically in the **Raw Layer**, so you can take advantage of structured storage and reliable querying right away. From there, the architecture flows naturally:

1. **Data is stored in Delta format**\
   Insertions, updates, and deletions are fully logged and versioned.

2. **Users manage transformations in Trusted and Service Layers**\
   Clean, standardize, and prepare your data based on trusted Delta-backed sources.

3. **Time Travel empowers recovery and analysis**\
   Go back to a previous version of your table whenever needed.

This design ensures that every stage of your pipeline is reliable, traceable, and scalable.

***

### Key Features of Delta Tables

#### **Version Control**

Each write operation creates a new version of your table. This makes it easy to:

* Reproduce past analyses
* Audit changes
* Debug issues in your pipeline

#### **Schema Evolution**

Delta Tables can detect and adapt to changes in your data schema, so your workflows remain flexible without sacrificing integrity.

#### **Efficient Storage**

Delta Tables use compression and intelligent caching to reduce storage costs while improving performance.

***

### Time Travel

Delta Tables in Nekt support **time travel**, allowing you to query previous versions of your data. This is particularly useful for debugging, audits, or restoring deleted records.

Default retention settings:

* **Delta Log Retention Duration:** 30 days\
  You can navigate past table versions for up to 30 days.

* **Delta Deleted File Retention Duration:** 7 days\
  Deleted files are retained for an additional 7 days after the log expires.\
  (Access to these files requires a manual request.)

> Both settings can be customized in the **Settings** tab of each table.

#### Example:

If your table is updated daily:

* You can go back up to 30 days using time travel.
* After 30 days, the physical files are retained for 7 more days.
* After 37 days, the data becomes unrecoverable unless otherwise configured.

***

### Delta Tables + AI/ML

Delta Tables provide the performance, consistency, and history needed for training and deploying **machine learning models**. You can trust that your input data is:

* Clean and versioned
* Easily reproducible
* Governed with full audit trails

Whether you're building dashboards or training models, Delta Tables support high-quality, production-grade workflows.

***

### **Explore Delta Tables in Nekt**

Delta Tables are the **backbone of structured data management in Nekt**. By combining speed, reliability, and flexibility, they help you manage your data with confidence—whether you're exploring trends, training ML models, or simply keeping your pipelines clean.

> Ready to dive deeper? Open a table in the **Catalog**, visit the **Settings** tab, and start exploring your Delta-backed data today.


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