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6.7 KiB
6.7 KiB
slug |
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/en/operations/system-tables/dictionaries |
dictionaries
Contains information about dictionaries.
Columns:
database
(String) — Name of the database containing the dictionary created by DDL query. Empty string for other dictionaries.name
(String) — Dictionary name.uuid
(UUID) — Dictionary UUID.status
(Enum8) — 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 query, timeout, dictionary config has changed).FAILED_AND_RELOADING
— Could not load the dictionary as a result of an error and is loading now.
origin
(String) — Path to the configuration file that describes the dictionary.type
(String) — Type of a dictionary allocation. Storing Dictionaries in Memory.key.names
(Array(String)) — Array of key names provided by the dictionary.key.types
(Array(String)) — Corresponding array of key types provided by the dictionary.attribute.names
(Array(String)) — Array of attribute names provided by the dictionary.attribute.types
(Array(String)) — Corresponding array of attribute types provided by the dictionary.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.found_rate
(Float64) — The percentage of uses for which the value was found.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
(String) — Text describing the data source for the dictionary.lifetime_min
(UInt64) — Minimum lifetime of the dictionary in memory, after which ClickHouse tries to reload the dictionary (ifinvalidate_query
is set, then only if it has changed). Set in seconds.lifetime_max
(UInt64) — Maximum lifetime of the dictionary in memory, after which ClickHouse tries to reload the dictionary (ifinvalidate_query
is set, then only if it has changed). Set in seconds.loading_start_time
(DateTime) — Start time for loading the dictionary.last_successful_update_time
(DateTime) — End time for loading or updating the dictionary. Helps to monitor some troubles with dictionary sources and investigate the causes.loading_duration
(Float32) — Duration of a dictionary loading.last_exception
(String) — Text of the error that occurs when creating or reloading the dictionary if the dictionary couldn’t be created.comment
(String) — Text of the comment to dictionary.
Example
Configure the dictionary:
CREATE DICTIONARY dictionary_with_comment
(
id UInt64,
value String
)
PRIMARY KEY id
SOURCE(CLICKHOUSE(HOST 'localhost' PORT tcpPort() TABLE 'source_table'))
LAYOUT(FLAT())
LIFETIME(MIN 0 MAX 1000)
COMMENT 'The temporary dictionary';
Make sure that the dictionary is loaded.
SELECT * FROM system.dictionaries LIMIT 1 FORMAT Vertical;
Row 1:
──────
database: default
name: dictionary_with_comment
uuid: 4654d460-0d03-433a-8654-d4600d03d33a
status: NOT_LOADED
origin: 4654d460-0d03-433a-8654-d4600d03d33a
type:
key.names: ['id']
key.types: ['UInt64']
attribute.names: ['value']
attribute.types: ['String']
bytes_allocated: 0
query_count: 0
hit_rate: 0
found_rate: 0
element_count: 0
load_factor: 0
source:
lifetime_min: 0
lifetime_max: 0
loading_start_time: 1970-01-01 00:00:00
last_successful_update_time: 1970-01-01 00:00:00
loading_duration: 0
last_exception:
comment: The temporary dictionary