ClickHouse/docs/en/sql-reference/statements/create/dictionary.md

slug	sidebar_position	sidebar_label	title
/en/sql-reference/statements/create/dictionary	38	DICTIONARY	CREATE DICTIONARY

Creates a new dictionary with given structure, source, layout and lifetime.

Syntax

CREATE [OR REPLACE] DICTIONARY [IF NOT EXISTS] [db.]dictionary_name [ON CLUSTER cluster]
(
    key1 type1  [DEFAULT|EXPRESSION expr1] [IS_OBJECT_ID],
    key2 type2  [DEFAULT|EXPRESSION expr2],
    attr1 type2 [DEFAULT|EXPRESSION expr3] [HIERARCHICAL|INJECTIVE],
    attr2 type2 [DEFAULT|EXPRESSION expr4] [HIERARCHICAL|INJECTIVE]
)
PRIMARY KEY key1, key2
SOURCE(SOURCE_NAME([param1 value1 ... paramN valueN]))
LAYOUT(LAYOUT_NAME([param_name param_value]))
LIFETIME({MIN min_val MAX max_val | max_val})
SETTINGS(setting_name = setting_value, setting_name = setting_value, ...)
COMMENT 'Comment'

The dictionary structure consists of attributes. Dictionary attributes are specified similarly to table columns. The only required attribute property is its type, all other properties may have default values.

ON CLUSTER clause allows creating dictionary on a cluster, see Distributed DDL.

Depending on dictionary layout one or more attributes can be specified as dictionary keys.

SOURCE

The source for a dictionary can be a:

• table in the current ClickHouse service
• table in a remote ClickHouse service
• file available by HTTP(S)
• another database

Create a dictionary from a table in the current ClickHouse service

Input table source_table:

┌─id─┬─value──┐
│  1 │ First  │
│  2 │ Second │
└────┴────────┘

Creating the dictionary:

CREATE DICTIONARY id_value_dictionary
(
    id UInt64,
    value String
)
PRIMARY KEY id
SOURCE(CLICKHOUSE(TABLE 'source_table'))
LAYOUT(FLAT())
LIFETIME(MIN 0 MAX 1000)

Output the dictionary:

SHOW CREATE DICTIONARY id_value_dictionary;

CREATE DICTIONARY default.id_value_dictionary
(
    `id` UInt64,
    `value` String
)
PRIMARY KEY id
SOURCE(CLICKHOUSE(TABLE 'source_table'))
LIFETIME(MIN 0 MAX 1000)
LAYOUT(FLAT())

Create a dictionary from a table in a remote ClickHouse service

Input table (in the remote ClickHouse service) source_table:

┌─id─┬─value──┐
│  1 │ First  │
│  2 │ Second │
└────┴────────┘

Creating the dictionary:

CREATE DICTIONARY id_value_dictionary
(
    id UInt64,
    value String
)
PRIMARY KEY id
SOURCE(CLICKHOUSE(HOST 'HOSTNAME' PORT 9000 USER 'default' PASSWORD 'PASSWORD' TABLE 'source_table' DB 'default'))
LAYOUT(FLAT())
LIFETIME(MIN 0 MAX 1000)

Create a dictionary from a file available by HTTP(S)

CREATE DICTIONARY default.taxi_zone_dictionary
(
    `LocationID` UInt16 DEFAULT 0,
    `Borough` String,
    `Zone` String,
    `service_zone` String
)
PRIMARY KEY LocationID
SOURCE(HTTP(URL 'https://datasets-documentation.s3.eu-west-3.amazonaws.com/nyc-taxi/taxi_zone_lookup.csv' FORMAT 'CSVWithNames'))
LIFETIME(MIN 0 MAX 0)
LAYOUT(HASHED())

Create a dictionary from another database

Please see the details in Dictionary sources.

See Also

• For more information, see the Dictionaries section.
• system.dictionaries — This table contains information about Dictionaries.