ClickHouse/docs/en/engines/table-engines/integrations/iceberg.md

slug	sidebar_position	sidebar_label
/en/engines/table-engines/integrations/iceberg	90	Iceberg

Iceberg Table Engine

This engine provides a read-only integration with existing Apache Iceberg tables in Amazon S3, Azure and locally stored tables.

Create Table

Note that the Iceberg table must already exist in the storage, this command does not take DDL parameters to create a new table.

CREATE TABLE iceberg_table_s3
    ENGINE = IcebergS3(url,  [, NOSIGN | access_key_id, secret_access_key, [session_token]], format, [,compression])

CREATE TABLE iceberg_table_azure
    ENGINE = IcebergAzure(connection_string|storage_account_url, container_name, blobpath, [account_name, account_key, format, compression])

CREATE TABLE iceberg_table_local
    ENGINE = IcebergLocal(path_to_table, [,format] [,compression_method])

Engine arguments

Description of the arguments coincides with description of arguments in engines S3, AzureBlobStorage and File correspondingly. format stands for the format of data files in the Iceberg table.

Engine parameters can be specified using Named Collections

Example

CREATE TABLE iceberg_table ENGINE=IcebergS3('http://test.s3.amazonaws.com/clickhouse-bucket/test_table', 'test', 'test')

Using named collections:

<clickhouse>
    <named_collections>
        <iceberg_conf>
            <url>http://test.s3.amazonaws.com/clickhouse-bucket/</url>
            <access_key_id>test</access_key_id>
            <secret_access_key>test</secret_access_key>
        </iceberg_conf>
    </named_collections>
</clickhouse>

CREATE TABLE iceberg_table ENGINE=IcebergS3(iceberg_conf, filename = 'test_table')

Aliases

Table engine Iceberg is an alias to IcebergS3 now.

Schema Evolution At the moment, with the help of CH, you can read iceberg tables, the schema of which has changed over time. We currently support reading tables where columns have been added and removed, and their order has changed. You can also change a column where a value is required to one where NULL is allowed. Additionally, we support permitted type casting for simple types, namely:  

• int -> long
• float -> double
• decimal(P, S) -> decimal(P', S) where P' > P.

Currently, it is not possible to change nested structures or the types of elements within arrays and maps.

See also

• iceberg table function