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This is an extension to the deltaLake table function. Allows processing files from Delta Lake tables in Amazon S3 in parallel from many nodes in a specified cluster. On initiator it creates a connection to all nodes in the cluster and dispatches each file dynamically. On the worker node it asks the initiator about the next task to process and processes it. This is repeated until all tasks are finished.

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Syntax

deltaLakeCluster(cluster_name, url [,aws_access_key_id, aws_secret_access_key] [,format] [,structure] [,compression] [,extra_credentials])
deltaLakeCluster(cluster_name, named_collection[, option=value [,..]])

deltaLakeS3Cluster(cluster_name, url [,aws_access_key_id, aws_secret_access_key] [,format] [,structure] [,compression] [,extra_credentials])
deltaLakeS3Cluster(cluster_name, named_collection[, option=value [,..]])

deltaLakeAzureCluster(cluster_name, connection_string|storage_account_url, container_name, blobpath, [,account_name], [,account_key] [,format] [,compression_method])
deltaLakeAzureCluster(cluster_name, named_collection[, option=value [,..]])
deltaLakeS3Cluster is an alias to deltaLakeCluster, both are for S3.

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Arguments

  • cluster_name — Name of a cluster that is used to build a set of addresses and connection parameters to remote and local servers.
  • Description of all other arguments coincides with description of arguments in equivalent deltaLake table function.
  • An optional extra_credentials parameter can be used to pass a role_arn for role-based access in ClickHouse Cloud. See Secure S3 for configuration steps.

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Returned value

A table with the specified structure for reading data from cluster in the specified Delta Lake table in S3.

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Virtual Columns

  • _path — Path to the file. Type: LowCardinality(String).
  • _file — Name of the file. Type: LowCardinality(String).
  • _size — Size of the file in bytes. Type: Nullable(UInt64). If the file size is unknown, the value is NULL.
  • _time — Last modified time of the file. Type: Nullable(DateTime). If the time is unknown, the value is NULL.
  • _etag — The etag of the file. Type: LowCardinality(String). If the etag is unknown, the value is NULL.