S3 Table Engine 

This engine provides integration with Amazon S3 ecosystem. This engine is similar to the HDFS engine, but provides S3-specific features.

Create Table 

CREATE TABLE s3_engine_table (name String, value UInt32) 
ENGINE = S3(path, [aws_access_key_id, aws_secret_access_key,] format, structure, [compression])

Engine parameters

  • path — Bucket url with path to file. Supports following wildcards in readonly mode: *, ?, {abc,def} and {N..M} where N, M — numbers, 'abc', 'def' — strings. For more information see below.
  • format — The format of the file.
  • structure — Structure of the table. Format 'column1_name column1_type, column2_name column2_type, ...'.
  • compression — Compression type. Supported values: none, gzip/gz, brotli/br, xz/LZMA, zstd/zst. Parameter is optional. By default, it will autodetect compression by file extension.

Example:

1. Set up the s3_engine_table table:

CREATE TABLE s3_engine_table (name String, value UInt32) ENGINE=S3('https://storage.yandexcloud.net/my-test-bucket-768/test-data.csv.gz', 'CSV', 'name String, value UInt32', 'gzip')

2. Fill file:

INSERT INTO s3_engine_table VALUES ('one', 1), ('two', 2), ('three', 3)

3. Query the data:

SELECT * FROM s3_engine_table LIMIT 2
┌─name─┬─value─┐
│ one  │     1 │
│ two  │     2 │
└──────┴───────┘

Virtual columns 

  • _path — Path to the file.
  • _file — Name of the file.

For more information about virtual columns see here.

Implementation Details 

  • Reads and writes can be parallel
  • Not supported:
    • ALTER and SELECT...SAMPLE operations.
    • Indexes.
    • Replication.

Wildcards In Path 

path argument can specify multiple files using bash-like wildcards. For being processed file should exist and match to the whole path pattern. Listing of files is determined during SELECT (not at CREATE moment).

  • * — Substitutes any number of any characters except / including empty string.
  • ? — Substitutes any single character.
  • {some_string,another_string,yet_another_one} — Substitutes any of strings 'some_string', 'another_string', 'yet_another_one'.
  • {N..M} — Substitutes any number in range from N to M including both borders. N and M can have leading zeroes e.g. 000..078.

Constructions with {} are similar to the remote table function.

S3-related Settings 

The following settings can be set before query execution or placed into configuration file.

  • s3_max_single_part_upload_size — The maximum size of object to upload using singlepart upload to S3. Default value is 64Mb.
  • s3_min_upload_part_size — The minimum size of part to upload during multipart upload to S3 Multipart upload. Default value is 512Mb.
  • s3_max_redirects — Max number of S3 redirects hops allowed. Default value is 10.

Security consideration: if malicious user can specify arbitrary S3 URLs, s3_max_redirects must be set to zero to avoid SSRF attacks; or alternatively, remote_host_filter must be specified in server configuration.

Endpoint-based Settings 

The following settings can be specified in configuration file for given endpoint (which will be matched by exact prefix of a URL):

  • endpoint — Specifies prefix of an endpoint. Mandatory.
  • access_key_id and secret_access_key — Specifies credentials to use with given endpoint. Optional.
  • use_environment_credentials — If set to true, S3 client will try to obtain credentials from environment variables and Amazon EC2 metadata for given endpoint. Optional, default value is false.
  • header — Adds specified HTTP header to a request to given endpoint. Optional, can be speficied multiple times.
  • server_side_encryption_customer_key_base64 — If specified, required headers for accessing S3 objects with SSE-C encryption will be set. Optional.

Example:

<s3>
    <endpoint-name>
        <endpoint>https://storage.yandexcloud.net/my-test-bucket-768/</endpoint>
        <!-- <access_key_id>ACCESS_KEY_ID</access_key_id> -->
        <!-- <secret_access_key>SECRET_ACCESS_KEY</secret_access_key> -->
        <!-- <use_environment_credentials>false</use_environment_credentials> -->
        <!-- <header>Authorization: Bearer SOME-TOKEN</header> -->
        <!-- <server_side_encryption_customer_key_base64>BASE64-ENCODED-KEY</server_side_encryption_customer_key_base64> -->
    </endpoint-name>
</s3>

Usage 

Suppose we have several files in TSV format with the following URIs on HDFS:

  1. There are several ways to make a table consisting of all six files:
CREATE TABLE table_with_range (name String, value UInt32) 
ENGINE = S3('https://storage.yandexcloud.net/my-test-bucket-768/{some,another}_prefix/some_file_{1..3}', 'CSV');
  1. Another way:
CREATE TABLE table_with_question_mark (name String, value UInt32) 
ENGINE = S3('https://storage.yandexcloud.net/my-test-bucket-768/{some,another}_prefix/some_file_?', 'CSV');
  1. Table consists of all the files in both directories (all files should satisfy format and schema described in query):
CREATE TABLE table_with_asterisk (name String, value UInt32) 
ENGINE = S3('https://storage.yandexcloud.net/my-test-bucket-768/{some,another}_prefix/*', 'CSV');
  1. Create table with files named file-000.csv, file-001.csv, … , file-999.csv:
CREATE TABLE big_table (name String, value UInt32) 
ENGINE = S3('https://storage.yandexcloud.net/my-test-bucket-768/big_prefix/file-{000..999}.csv', 'CSV');

See also 

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