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docs/doc/15-sql-functions/111-system-functions/fuse_encoding.md

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+---
+title: FUSE_ENCODING
+---
+import FunctionDescription from '@site/src/components/FunctionDescription';
+
+<FunctionDescription description="Introduced or updated: v1.2.162"/>
+
+Returns the encoding types applied to a specific column within a table. It helps you understand how data is compressed and stored in a native format within the table.
+
+## Syntax
+
+```sql
+FUSE_ENCODING('<database_name>', '<table_name>', '<column_name>')
+```
+
+The function returns a result set with the following columns:
+
+| Column            | Data Type        | Description                                                                                                                                                                              |
+|-------------------|------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| VALIDITY_SIZE     | Nullable(UInt32) | The size of a bitmap value that indicates whether each row in the column has a non-null value. This bitmap is used to track the presence or absence of null values in the column's data. |
+| COMPRESSED_SIZE   | UInt32           | The size of the column data after compression.                                                                                                                                           |
+| UNCOMPRESSED_SIZE | UInt32           | The size of the column data before applying encoding.                                                                                                                                    |
+| LEVEL_ONE         | String           | The primary or initial encoding applied to the column.                                                                                                                                   |
+| LEVEL_TWO         | Nullable(String) | A secondary or recursive encoding method applied to the column after the initial encoding.                                                                                               |
+
+## Examples
+
+```sql
+-- Create a table with an integer column 'c' and apply 'Lz4' compression
+CREATE TABLE t(c INT) STORAGE_FORMAT = 'native' COMPRESSION = 'lz4';
+
+-- Insert data into the table.
+INSERT INTO t SELECT number FROM numbers(2048);
+
+-- Analyze the encoding for column 'c' in table 't'
+SELECT LEVEL_ONE, LEVEL_TWO, COUNT(*) 
+FROM FUSE_ENCODING('default', 't', 'c') 
+GROUP BY LEVEL_ONE, LEVEL_TWO;
+
+level_one   |level_two|count(*)|
+------------+---------+--------+
+DeltaBitpack|         |       1|
+
+--  Insert 2,048 rows with the value 1 into the table 't'
+INSERT INTO t (c)
+SELECT 1
+FROM numbers(2048);
+
+SELECT LEVEL_ONE, LEVEL_TWO, COUNT(*) 
+FROM FUSE_ENCODING('default', 't', 'c') 
+GROUP BY LEVEL_ONE, LEVEL_TWO;
+
+level_one   |level_two|count(*)|
+------------+---------+--------+
+OneValue    |         |       1|
+DeltaBitpack|         |       1|
+```