COPY

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:

sql

  1. 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 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.

COPY FROM

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

The syntax for using COPY FROM is as follows:

sql

  1. COPY [<db>.]<table_name>
  2. FROM { '<path>/[<filename>]' }
  3. [ [ WITH ]
  4. (
  5. [ FORMAT = { parquet } ]
  6. [ PATTERN = '<regex_pattern>' ]
  7. )
  8. ]

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

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:

sql

  1. 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:

sql

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

WITH Options

OptionDescriptionRequired
FORMATTarget file(s) format, e.g., JSON, CSV, ParquetRequired
PATTERNUse regex to match files. e.g., *_today.parquetOptional

Connection Options

S3

When you try to copy data from(to) S3:

sql

  1. COPY tbl FROM '<url>' WITH (FORMAT = 'parquet') CONNECTION(BUCKET = 'us-west-2');.
URL

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

  1. S3://my-bucket/data.parquet

Another way is using Virtual-hosted–style. The following example shows the correct format.

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

You can set the following CONNECTION options:

OptionDescriptionRequired
REGIONAWS region name. e.g., us-east-1.Required
ENDPOINTThe bucket endpointOptional
ACCESS_KEY_IDACCESS_KEY_ID Your access key ID for connecting the AWS S3 compatible object storage.Optional
SECRET_ACCESS_KEYYour secret access key for connecting the AWS S3 compatible object storage.Optional
ENABLE_VIRTUAL_HOST_STYLEIf you use virtual hosting to address the bucket, set it to “true”.Optional
SESSION_TOKENYour temporary credential for connecting the AWS S3 service.Optional