> For the complete documentation index, see [llms.txt](https://docs.e6data.com/query-engine/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.e6data.com/query-engine/guides/table-formats/delta-lake.md).

# Delta Lake

How e6data queries Delta Lake tables through external catalogs, what's supported, and how to connect.

e6data supports querying **Delta Lake** tables through external catalogs such as **AWS Glue**, **Hive Metastore**, **Microsoft Fabric**, and **Unity Catalog**.

<table><thead><tr><th>Capability</th><th>Support</th><th data-hidden>Description</th></tr></thead><tbody><tr><td><strong>Deletion vectors</strong></td><td>Supported</td><td>Marks deleted or updated rows without immediately rewriting the underlying Parquet files.</td></tr><tr><td><strong>CHECK constraints</strong></td><td>Supported</td><td>Enforces defined conditions on table data and rejects invalid writes.</td></tr><tr><td><strong>Change Data Feed (CDF)</strong></td><td>Supported</td><td>Captures row-level inserts, updates, and deletes between table versions.</td></tr><tr><td><strong>Generated columns</strong></td><td>Supported</td><td>Automatically calculates column values using expressions based on other columns.</td></tr><tr><td><strong>Column mapping</strong></td><td>Supported</td><td>Allows columns to be renamed or dropped without rewriting existing data files.</td></tr><tr><td><strong>Identity columns</strong></td><td>Supported</td><td>Automatically generates sequential numeric values for inserted rows.</td></tr><tr><td><strong>Row tracking</strong></td><td>Supported</td><td>Assigns stable row identifiers and tracks when each row was last modified.</td></tr><tr><td><strong>Timestamp NTZ</strong></td><td>Supported</td><td>Stores timestamp values without timezone information or timezone conversion.</td></tr><tr><td><strong>Liquid clustering</strong></td><td>Supported</td><td>Organizes data using clustering columns that can evolve as access patterns change.</td></tr><tr><td><strong>Iceberg readers through UniForm</strong></td><td>Supported</td><td>Generates Iceberg-compatible metadata so compatible Iceberg engines can read the Delta table.</td></tr><tr><td><strong>Type widening</strong></td><td>Supported</td><td>Allows compatible changes to wider data types without rewriting existing data files.</td></tr><tr><td><strong><code>VARIANT</code></strong></td><td>Supported</td><td>Stores and queries semi-structured data such as JSON objects, arrays, and scalar values.</td></tr></tbody></table>

## Sample queries

```sql
-- List all tables in a namespace
SHOW TABLES FROM delta_catalog.analytics;

-- Query from a Delta table
SELECT *
FROM delta_catalog.analytics.user_activity
WHERE event_type = 'purchase';
```

## See also

* [Catalogs overview](/query-engine/guides/catalogs.md)
* [Table formats overview](/query-engine/guides/table-formats.md)


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://docs.e6data.com/query-engine/guides/table-formats/delta-lake.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.