# NCACHE.CREATE

> Create a negative cache namespace with an optional entry limit and default TTL.

URL: https://docs.hotkv.com/commands/ncache-create/

```
NCACHE.CREATE namespace [MAX_ENTRIES n] [TTL seconds]
```

- Group: Keyed caches
- Complexity: O(1)
- HotKV Cloud: Performance and Scale plans
- On-Premise: requires the negative-cache license feature

The negative cache holds negative results, such as "user not found" or "refused by moderation", usually with a short TTL, so repeated lookups for the same missing or refused item do not reach your backend or model again. `NCACHE.CREATE` creates a namespace. You must create a
namespace before you can store entries in it with [NCACHE.SET](https://docs.hotkv.com/commands/ncache-set/index.md).

## Options

| Option | Effect |
| --- | --- |
| `MAX_ENTRIES n` | Maximum number of entries. `0` or omitted uses the server's per-namespace limit, and larger values are capped at that limit (`max_entries_per_namespace` under `[ncache]`). When the namespace is full, HotKV evicts existing entries to make room. |
| `TTL seconds` | Default time to live for entries stored without their own `TTL`. `0` or omitted means entries do not expire. |

Options can be given in any order and are case-insensitive.

## Return value

| Case | RESP2 | RESP3 |
| --- | --- | --- |
| Namespace created | Simple string `OK` | Same |

Errors:

- `ERR namespace already exists or limit reached` if the namespace exists, or the server already holds its maximum number of negative cache namespaces (`max_namespaces` under `[ncache]`).
- `ERR invalid MAX_ENTRIES` or `ERR invalid TTL` if a value is not a non-negative integer.
- `ERR unknown option` for any other option name.
- `ERR wrong number of arguments for 'ncache.create' command` if the argument count is wrong.
- `NOLICENSE negative-cache requires a HotKV license. Contact sales@hotkv.com` if your license does not include the `negative-cache` feature.

## Examples

```
127.0.0.1:6379> NCACHE.CREATE lookups MAX_ENTRIES 50000 TTL 60
OK
127.0.0.1:6379> NCACHE.CREATE lookups
(error) ERR namespace already exists or limit reached
```

## Compatibility

HotKV-only command. Redis and Valkey have no equivalent.

## See also

[NCACHE.SET](https://docs.hotkv.com/commands/ncache-set/index.md), [NCACHE.GET](https://docs.hotkv.com/commands/ncache-get/index.md), [NCACHE.DEL](https://docs.hotkv.com/commands/ncache-del/index.md), [NCACHE.STATS](https://docs.hotkv.com/commands/ncache-stats/index.md), [NCACHE.FLUSH](https://docs.hotkv.com/commands/ncache-flush/index.md), [NCACHE.DROP](https://docs.hotkv.com/commands/ncache-drop/index.md), [NCACHE.LIST](https://docs.hotkv.com/commands/ncache-list/index.md), [AI features guide](https://docs.hotkv.com/ai-features/index.md)