ClickHouse/docs/en/sql-reference/dictionaries/external-dictionaries/external-dicts-dict.md

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---
toc_priority: 40
toc_title: Configuring an External Dictionary
---
# Configuring an External Dictionary {#dicts-external-dicts-dict}
If dictionary is configured using xml file, than dictionary configuration has the following structure:
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``` xml
<dictionary>
<name>dict_name</name>
<structure>
<!-- Complex key configuration -->
</structure>
<source>
<!-- Source configuration -->
</source>
<layout>
<!-- Memory layout configuration -->
</layout>
<lifetime>
<!-- Lifetime of dictionary in memory -->
</lifetime>
</dictionary>
```
Corresponding [DDL-query](../../../sql-reference/statements/create/dictionary.md) has the following structure:
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``` sql
CREATE DICTIONARY dict_name
(
... -- attributes
)
PRIMARY KEY ... -- complex or single key configuration
SOURCE(...) -- Source configuration
LAYOUT(...) -- Memory layout configuration
LIFETIME(...) -- Lifetime of dictionary in memory
```
- `name` The identifier that can be used to access the dictionary. Use the characters `[a-zA-Z0-9_\-]`.
- [source](../../../sql-reference/dictionaries/external-dictionaries/external-dicts-dict-sources.md) — Source of the dictionary.
- [layout](../../../sql-reference/dictionaries/external-dictionaries/external-dicts-dict-layout.md) — Dictionary layout in memory.
- [structure](../../../sql-reference/dictionaries/external-dictionaries/external-dicts-dict-structure.md) — Structure of the dictionary . A key and attributes that can be retrieved by this key.
- [lifetime](../../../sql-reference/dictionaries/external-dictionaries/external-dicts-dict-lifetime.md) — Frequency of dictionary updates.