3.3

COPY TO

Export table contents to files on CrateDB node machines.

Table of Contents

Synopsis

COPY table_ident [ PARTITION ( partition_column = value [ , ... ] ) ]
                 [ ( column [ , ...] ) ]
                 [ WHERE condition ]
                 TO DIRECTORY output_uri
                 [ WITH ( copy_parameter [= value] [, ... ] ) ]

Description

The COPY TO command exports the contents of a table to one or more files into a given directory with unique filenames. Each node with at least one shard of the table will export its contents onto their local disk.

The created files are JSON formatted and contain one table row per line and, due to the distributed nature of CrateDB, will remain on the same nodes where the shards are.

Note

Currently only user tables can be exported. System tables like sys.nodes and blob tables don’t work with the COPY TO statement.

Parameters

table_ident

The name (optionally schema-qualified) of the table to be exported.

column

(optional) A list of column expressions that should be exported.

Note

Declaring columns changes the output to JSON list format, which is currently not supported by the COPY FROM statement.

Clauses

WHERE

WHERE clauses use the same syntax as SELECT statements, allowing partial exports. (see WHERE Clause for more information).

Output URI

The output_uri can be any expression evaluating to a string.

The resulting string should be a valid URI of one of the supporting schemes:

  • file://

  • s3://[<accesskey>:<secretkey>@]<bucketname>/<path>

If no scheme is given (e.g.: ‘/path/to/dir’) the default uri-scheme file:// will be used.

Note

A secretkey provided by Amazon Web Service can contain characters such as ‘/’, ‘+’ or ‘=’. Such characters must be URI encoded. The same encoding as in s3 applies.

Additionally, versions prior to 0.51.x use HTTP for connections to S3. Since 0.51.x these connections are using the HTTPS protocol. Please make sure you update your firewall rules to allow outgoing connections on port 443.

Clauses

PARTITION

If the table is partitioned this clause can be used to only export data from a specific partition.

The exported data doesn’t contain the partition columns or values as they are not part of the partitioned tables.

[ PARTITION ( partition_column = value [ , ... ] ) ]
partition_column

The name of the column by which the table is partitioned. All partition columns that were part of the PARTITIONED BY of the CREATE TABLE statement must be specified.

value

The columns value.

Note

If COPY TO is used on a partitioned table without the PARTITION clause, the partition columns and values will be included in the rows of the exported files. If a partition column is a generated column, it will not be included even if the PARTITION clause is missing.

WITH

The optional WITH clause can specify parameters for the copy statement.

[ WITH ( copy_parameter [= value] [, ... ] ) ]

Possible copy_parameters are:

compression

Define if and how the exported data should be compressed.

By default the output is not compressed.

Possible values for the compression setting are:

gzip

Use gzip to compress the data output.

format

Optional parameter to override default output behavior.

Possible values for the format settings are:

json_object

Each row in the result set is serialized as JSON object and written to an output file where one line contains one object. This is the default behavior if no columns are defined. Use this format to import with COPY FROM.

json_array

Each row in the result set is serialized as JSON array, storing one array per line in an output file. This is the default behavior if columns are defined.