---
title: "Lusid.RelationalDataset.Definition"
slug: "lusidrelationaldatasetdefinition"
updated: 2026-01-19T12:33:53Z
published: 2026-01-19T12:33:53Z
canonical: "support.lusid.com/lusidrelationaldatasetdefinition"
---

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

# Lusid.RelationalDataset.Definition

| **Type** | **Read/write** | **Author** | **Availability** |
| --- | --- | --- | --- |
| [Data provider](/v1/docs/what-are-a-data-provider-and-a-direct-provider) | Read | FINBOURNE | Provided with LUSID |

The `Lusid.RelationalDataset.Definition` provider enables you to write a [Luminesce SQL query](/v1/docs/understanding-the-luminesce-sql-query-syntax) that retrieves information about [relational dataset definitions](/v1/docs/how-do-i-create-a-relational-dataset-definition) (RDDs).

One row is returned for each `SeriesIdentifier`, `Value` and `Metadata` field in each RDD.

**See also**: [Lusid.RelationalDataset.Definition.Writer](/v1/docs/lusidrelationaldatasetdefinitionwriter)

## Basic usage

```sql
select * from Lusid.RelationalDataset.Definition where <filter-expression>;
```

## Query parameters

`Lusid.RelationalDataset.Definition` has parameters that enable you to filter or refine a query.

To list available parameters, their data types, default values, and an explanation for each, run a query like this one using a [suitable tool](/v1/docs/what-tools-are-available-to-write-luminesce-queries):

```sql
select FieldName, DataType, ParamDefaultValue, Description from Sys.Field 
  where TableName = 'Lusid.RelationalDataset.Definition' and FieldType = 'Parameter';
```

## Data fields

By default, `Lusid.RelationalDataset.Definition` returns a table of data populated with particular fields (columns). You can return a subset of these fields.

To list fields available to return, their data types, whether fields are considered 'main', and an explanation for each, run a query like this one using a [suitable tool](/v1/docs/what-tools-are-available-to-write-luminesce-queries):

```sql
select FieldName, DataType, IsMain, IsPrimaryKey, SampleValues, Description from Sys.Field 
  where TableName = 'Lusid.RelationalDataset.Definition' and FieldType = 'Column';
```

> **Note:** Fields marked 'main' are returned by queries that select a caret character, for example `select ^ from Lusid.RelationalDataset.Definition`

## Examples

> **Note:** For more example Luminesce SQL queries, visit our [Github repo](https://github.com/finbourne/luminesce-examples/tree/master/examples).

### Example 1: Retrieve every field for every RDD

```sql
select * from Lusid.RelationalDataset.Definition;
```

### Example 2: Retrieve the fields for a particular RDD

```sql
select * from Lusid.RelationalDataset.Definition 
  where Scope = 'MyRDDs' and Code = 'Addresses';
```

### Example 3: Retrieve one row per RDD

You can pivot the results through the [Tools.Pivot](/v1/docs/toolspivot) provider to display fields as columns, reducing the number of rows and possibly making the results more intuitive:

```sql
@results = select * from Lusid.RelationalDataset.Definition;

@pivoted_results = use Tools.Pivot with @results
--key=FieldName
--aggregateColumns=FieldCategory,FieldRequired,FieldDataTypeScope,FieldDataTypeCode,FieldDisplayName,FieldDescription
enduse;
select * from @pivoted_results;
```