> ## Documentation Index
> Fetch the complete documentation index at: https://docs.regatta.dev/llms.txt
> Use this file to discover all available pages before exploring further.
# Introduction
This section describes the RegattaDB SQL specification for vector indexing.
The RegattaDB specification follows the style of the `pgvector `extension of PostgreSQL. As in other parts of the SQL specification, there are deviations from PostgreSQL where needed to support RegattaDB’s performance and functionality.
## The Vector Data Type
In order to support vector indexing and searches, we introduce the `VECTOR `type. This type is not a generic vector. A `VECTOR `column has one parameter that defines the dimension of all the vectors in the table column. In addition, the following applies to vector columns:
* A vector column’s dimension can be any integer between 1 and 2048 (inclusive).
* The data type of the vector elements is` REAL (FLOAT4) `
* Elements of the vector cannot be `NULL` and cannot have any of the values Infinity, -Infinity or NaN.
* A vector column can be nullable. The `NOT NULL` constraint is supported.
* `UNIQUE `and `PRIMARY KEY` constraints are not supported.
* A vector column cannot be a foreign key or target of a foreign key.
* Regular index for a vector column is not supported.
* Vector values are passed as strings following `pgvector `syntax.
For example:
```sql theme={null}
CREATE TABLE my_table (id INTEGER PRIMARY KEY INDEX, vec VECTOR(4));
INSERT INTO my_table VALUES (1, '[1,2,3,4]'), (2, '[1.4, 1.8, 2, 2.66]');
```
## Vector Index Operators
The following are binary operators that return the distance between two vectors. The vectors must be of the same dimension.
L2 distance
(negative) Inner product
Cosine distance
* No other operators or functions are supported for the vector type (e.g., no vector arithmetic such as adding vectors or multiplying a vector by a scalar).
* No aggregations are supported on vector columns.