COPY

COPY TABLE

COPY TO

COPY TO is used to export the contents of a table to a file.

The syntax for using COPY TO is as follows:

COPY tbl TO '/xxx/xxx/output.parquet' WITH (FORMAT = 'parquet');

The command starts with the keyword COPY, followed by the name of the table you want to export data from (tbl in this case).

TO specifies the file path and name to save the exported data (/xxx/xxx/output.parquet in this case).

WITH Option

WITH adds options such as the file FORMAT which specifies the format of the exported file. In this example, the format is Parquet; it is a columnar storage format used for big data processing. Parquet efficiently compresses and encodes columnar data for big data analytics.

Option	Description	Required
FORMAT	Target file(s) format, e.g., JSON, CSV, Parquet	Required
START_TIME/END_TIME	The time range within which data should be exported. START_TIME is inclusive and END_TIME is exclusive.	Optional

CONNECTION Option

COPY TO supports exporting data to cloud storage services like S3. See connect-to-s3 for more detail.

COPY FROM

COPY FROM is used to import data from a file into a table.

The syntax for using COPY FROM is as follows:

COPY [<db>.]<table_name>
FROM { '<path>/[<filename>]' }
[ [ WITH ]
 (
   [ FORMAT =  { 'CSV' | 'JSON' | 'PARQUET' | 'ORC' } ]
   [ PATTERN = '<regex_pattern>' ]
 )
]
[LIMIT NUM]

The command starts with the keyword COPY, followed by the name of the table you want to import data into.

WITH Option

FORMAT specifies the file format of the imported file. In this example, the format is Parquet.

The option PATTERN allows the usage of wildcard characters like * to specify multiple input files that match a certain pattern. For example, you can use the following syntax to import all files in the directory(which must be an absolute path) "/path/to/folder" with the filename that contains parquet:

COPY tbl FROM '/path/to/folder/' WITH (FORMAT = 'parquet', PATTERN = '.*parquet.*');

Specifically, if you only have one file to import, you can use the following syntax:

COPY tbl FROM '/path/to/folder/xxx.parquet' WITH (FORMAT = 'parquet');

Option	Description	Required
FORMAT	Target file(s) format, e.g., JSON, CSV, Parquet, ORC	Required
PATTERN	Use regex to match files. e.g., *_today.parquet	Optional

NOTE

The CSV file must have a header row to be imported correctly. The header row should contain the column names of the table.

CONNECTION Option

COPY FROM also supports importing data from cloud storage services like S3. See connect-to-s3 for more detail.

Connect to S3

You can copy data from/to S3

-- COPY FROM
COPY tbl FROM '<URL>' WITH (FORMAT = 'parquet') CONNECTION(REGION = 'us-west-2');

-- COPY TO
COPY tbl TO '<URL>' WITH (FORMAT = 'parquet') CONNECTION(REGION = 'us-west-2');

URL

Notes: You should specify a file using S3://bucket/key-name. The following example shows the correct format.

s3://my-bucket/data.parquet

Another way is using Virtual-hosted–style(ENABLE_VIRTUAL_HOST_STYLE must be set to true to enable this). The following example shows the correct format.

s3://bucket-name.s3.region-code.amazonaws.com/key-name

NOTE

You can use Copy S3 URI or COPY URL on S3 console to get S3 URI/HTTP URL prefix or full path.

Options

You can set the following CONNECTION options:

Option	Description	Required
REGION	AWS region name. e.g., us-west-2	Required
ENDPOINT	The bucket endpoint. e.g., s3.us-west-2.amazonaws.com	Optional
ACCESS_KEY_ID	ACCESS_KEY_ID Your access key ID for connecting the AWS S3 compatible object storage.	Optional
SECRET_ACCESS_KEY	Your secret access key for connecting the AWS S3 compatible object storage.	Optional
ENABLE_VIRTUAL_HOST_STYLE	If you use virtual hosting to address the bucket, set it to "true".	Optional
SESSION_TOKEN	Your temporary credential for connecting the AWS S3 service.	Optional

LIMIT

You can use LIMIT to restrict maximum number of rows inserted at once.

COPY DATABASE

Beside copying specific table to/from some path, COPY statement can also be used to copy whole database to/from some path. The syntax for copying databases is:

COPY DATABASE <db_name> 
  [TO | FROM] '<PATH>' 
  WITH (
    FORMAT = { 'CSV' | 'JSON' | 'PARQUET' },
    START_TIME = "<START TIMESTAMP>",
    END_TIME = "<END TIMESTAMP>"
  ) 
  [CONNECTION(
    REGION = "<REGION NAME>",
    ENDPOINT = "<ENDPOINT>",
    ACCESS_KEY_ID = "<ACCESS KEY>",
    SECRET_ACCESS_KEY = "<SECRET KEY>",
    ENABLE_VIRTUAL_HOST_STYLE = "[true | false]",
  )]

Option	Description	Required
FORMAT	Export file format, available options: JSON, CSV, Parquet	Required
START_TIME/END_TIME	The time range within which data should be exported. START_TIME is inclusive and END_TIME is exclusive.	Optional

• When copying databases, <PATH> must end with /.
• CONNECTION parameters can also be used to copying databases to/from object storage services like AWS S3.

Examples

-- Export all tables' data to /tmp/export/
COPY DATABASE public TO '/tmp/export/' WITH (FORMAT='parquet');

-- Export all tables' data within time range 2022-04-11 08:00:00~2022-04-11 09:00:00 to /tmp/export/
COPY DATABASE public TO '/tmp/export/' WITH (FORMAT='parquet', START_TIME='2022-04-11 08:00:00', END_TIME='2022-04-11 09:00:00');

-- Import files under /tmp/export/ directory to database named public.
COPY DATABASE public FROM '/tmp/export/' WITH (FORMAT='parquet');

Special reminder for Windows platforms

Please notice that when executing COPY/COPY DATABASE statements on Windows platforms, backslashes (\) in paths should be replaced with / for compatibility.

-- Won't work
COPY tbl TO 'C:\xxx\xxx\output.parquet' WITH (FORMAT = 'parquet');

-- Correct path:
COPY tbl TO 'C:/xxx/xxx/output.parquet' WITH (FORMAT = 'parquet');