ClickHouse/docs/zh/operations/system-tables/dictionaries.md

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系统。字典

包含以下信息 外部字典.

列:

• database (字符串) — Name of the database containing the dictionary created by DDL query. Empty string for other dictionaries.
• name (字符串) — 字典名称.
• status (枚举8) — Dictionary status. Possible values:
  • NOT_LOADED — Dictionary was not loaded because it was not used.
  • LOADED — Dictionary loaded successfully.
  • FAILED — Unable to load the dictionary as a result of an error.
  • LOADING — Dictionary is loading now.
  • LOADED_AND_RELOADING — Dictionary is loaded successfully, and is being reloaded right now (frequent reasons: SYSTEM RELOAD DICTIONARY 查询，超时，字典配置已更改）。
  • FAILED_AND_RELOADING — Could not load the dictionary as a result of an error and is loading now.
• origin (字符串) — Path to the configuration file that describes the dictionary.
• type (字符串) — Type of dictionary allocation. 在内存中存储字典.
• key — 密钥类型:数字键 (UInt64) or Сomposite key (字符串) — form “(type 1, type 2, ..., type n)”.
• attribute.names (阵列(字符串)) — Array of 属性名称 由字典提供。
• attribute.types (阵列(字符串)) — Corresponding array of 属性类型 这是由字典提供。
• bytes_allocated (UInt64) — Amount of RAM allocated for the dictionary.
• query_count (UInt64) — Number of queries since the dictionary was loaded or since the last successful reboot.
• hit_rate (Float64) — For cache dictionaries, the percentage of uses for which the value was in the cache.
• element_count (UInt64) — Number of items stored in the dictionary.
• load_factor (Float64) — Percentage filled in the dictionary (for a hashed dictionary, the percentage filled in the hash table).
• source (字符串) — Text describing the 数据源 为了字典
• lifetime_min (UInt64) — Minimum 使用寿命 在内存中的字典，之后ClickHouse尝试重新加载字典（如果 invalidate_query 被设置，那么只有当它已经改变）。 在几秒钟内设置。
• lifetime_max (UInt64) — Maximum 使用寿命 在内存中的字典，之后ClickHouse尝试重新加载字典（如果 invalidate_query 被设置，那么只有当它已经改变）。 在几秒钟内设置。
• loading_start_time (日期时间) — Start time for loading the dictionary.
• last_successful_update_time (日期时间) — End time for loading or updating the dictionary. Helps to monitor some troubles with external sources and investigate causes.
• loading_duration (Float32) — Duration of a dictionary loading.
• last_exception (字符串) — Text of the error that occurs when creating or reloading the dictionary if the dictionary couldn't be created.

示例

配置字典。

CREATE DICTIONARY dictdb.dict
(
    `key` Int64 DEFAULT -1,
    `value_default` String DEFAULT 'world',
    `value_expression` String DEFAULT 'xxx' EXPRESSION 'toString(127 * 172)'
)
PRIMARY KEY key
SOURCE(CLICKHOUSE(HOST 'localhost' PORT 9000 USER 'default' TABLE 'dicttbl' DB 'dictdb'))
LIFETIME(MIN 0 MAX 1)
LAYOUT(FLAT())

确保字典已加载。

SELECT * FROM system.dictionaries

┌─database─┬─name─┬─status─┬─origin──────┬─type─┬─key────┬─attribute.names──────────────────────┬─attribute.types─────┬─bytes_allocated─┬─query_count─┬─hit_rate─┬─element_count─┬───────────load_factor─┬─source─────────────────────┬─lifetime_min─┬─lifetime_max─┬──loading_start_time─┌──last_successful_update_time─┬──────loading_duration─┬─last_exception─┐
│ dictdb   │ dict │ LOADED │ dictdb.dict │ Flat │ UInt64 │ ['value_default','value_expression'] │ ['String','String'] │           74032 │           0 │        1 │             1 │ 0.0004887585532746823 │ ClickHouse: dictdb.dicttbl │            0 │            1 │ 2020-03-04 04:17:34 │   2020-03-04 04:30:34        │                 0.002 │                │
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