# Ent API: exists() by Expression

This is another privacy-unaware API call, similar to `count()`.

## **Ent.exists(vc, { field: "...", ... })**: boolean

Returns true if there isat least one Ent in the database matching the `where` condition. Works across multiple microshards too.

In terms of the logic, `exists()` call is similar to `count() > 0` check, with two performance optimizations:

1. It uses `EXISTS` SQL clause, which doesn’t read more tuples from the database than needed (as opposed to `count()` aggregate).
2. During the run, it severely reduces the weight (basically, the probability) of seqscan to happen (with `SET enable_seqscan=off` directive merged with the query). I.e. it implies that you must have a good index covering the `where` condition.

As all API calls in Ent Framework, multiple parallel `exists()` calls are batched into a single SQL query:

```typescript
const [exists1, exists2] = await Promise.all([
  EntTopic.exists(vc, { creator_id: "123" }),
  EntTopic.exists(vc, { updated_at: { $gt: new Date("2024-01-01") } }),
]);
```

This sends the following SQL query to the underlying database:

```sql
SET enable_seqscan=off;
SELECT EXISTS (SELECT true FROM topics WHERE creator_id='123')
  UNION ALL
SELECT EXISTS (SELECT true FROM topics WHERE created_at>'...')
```

The `exists()` call is even more useful to build custom privacy checks than `count()`, because it’s faster and almost guarantees using an index.


---

# Agent Instructions: 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:

```
GET https://docs.ent-framework.net/getting-started/ent-api-exists-by-expression.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
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.