ClickHouse/docs/zh/query_language/dicts/external_dicts_dict.md

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2020-04-03 13:23:32 +00:00
---
en_copy: true
---
# Configuring an External Dictionary {#dicts-external-dicts-dict}
If dictionary is configured using xml file, than dictionary configuration has the following structure:
``` 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](../create.md#create-dictionary-query) has the following structure:
``` 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](external_dicts_dict_sources.md) — Source of the dictionary.
- [layout](external_dicts_dict_layout.md) — Dictionary layout in memory.
- [structure](external_dicts_dict_structure.md) — Structure of the dictionary . A key and attributes that can be retrieved by this key.
- [lifetime](external_dicts_dict_lifetime.md) — Frequency of dictionary updates.
[Original article](https://clickhouse.tech/docs/en/query_language/dicts/external_dicts_dict/) <!--hide-->