---
title: Logical views
description: Reuse parameter-free typed queries that expand before checking, snapshot selection, and execution.
species: concept
---
# Logical views

A logical view is a named, parameter-free typesql query. Supernova expands it into the calling query before type checking, policy admission, snapshot selection, or execution.

```typesql
select customer_id, revenue
from finance.customer_revenue
where revenue > 1000
```

## What a logical view is

A logical view is reusable query text. It is not an Iceberg view and does not materialize data. Each reference expands to a parenthesized derived query with an unambiguous alias.

Definitions use 2-part `[schema, view]` or 3-part `[catalog, schema, view]` names. Matching is ASCII-case-insensitive by part, but the caller supplies one closed, authorized definition set.

## Expansion guarantees

Every supplied definition must contain exactly one query and no positional, named, or question-mark parameter. Expansion understands relation and qualification scopes; it does not use text substitution. A correlated subquery cannot capture a generated alias accidentally.

The expansion artifact records the authored query, expanded SQL, every used view, and a SHA-256 digest of each exact definition. That provenance participates in downstream identity.

## Diagnostics and limits

`TS0800` reports an invalid environment or definition. `TS0801` reports a cycle. `TS0802` reports a bound exceeded. `TS0803` reports an invalid logical-view document.

The environment admits up to 4,096 views and 64 expansion levels. The raw root SQL and decoded view SQL are bounded before expansion so an invalid environment fails without publishing a partial result.

Use a [model](/v2/docs/models/authoring) when you need a durable table. Use a logical view when reuse and type checking matter but materialization does not.