Creating an OBS Table Using the DataSource Syntax

Function

Create an OBS table using the DataSource syntax.

The main differences between the DataSource and the Hive syntax lie in the supported data formats and the number of supported partitions. For details, see syntax and precautions.

You are advised to use the OBS parallel file system for storage. A parallel file system is a high-performance file system that provides latency in milliseconds, TB/s-level bandwidth, and millions of IOPS. It applies to interactive big data analysis scenarios.

Precautions

• The size of a table is not calculated when the table is created.
• When data is added, the table size will be changed to 0.
• You can check the table size on OBS.
• Table properties cannot be specified using CTAS table creation statements.
• An OBS directory containing subdirectories:

  If you specify an OBS directory that contains subdirectories when creating a table, all file types and content within those subdirectories will also be included as table content.

  Ensure that all file types in the specified directory and its subdirectories are consistent with the storage format specified in the table creation statement. All file content must be consistent with the fields in the table. Otherwise, errors will be reported in the query.

  You can set multiLevelDirEnable to true in the OPTIONS statement to query the content in the subdirectory. The default value is false (Note that this configuration item is a table attribute, exercise caution when performing this operation. Hive tables do not support this configuration item.)

• Instructions on using partitioned tables:
  • When a partitioned table is created, the column specified in PARTITIONED BY must be a column in the table, and the partition type must be specified. The partition column supports only the string, boolean, tinyint, smallint, short, int, bigint, long, decimal, float, double, date, and timestamp type.
  • When a partitioned table is created, the partition field must be the last one or several fields of the table field, and the sequence of the partition fields must be the same. Otherwise, an error occurs.
  • A maximum of 200,000 partitions can be created in a single table.
  • CTAS table creation statements cannot be used to create partitioned tables.

Syntax

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CREATE TABLE [IF NOT EXISTS] [db_name.]table_name 
  [(col_name1 col_type1 [COMMENT col_comment1], ...)]
  USING file_format 
  [OPTIONS (path 'obs_path', key1=val1, key2=val2, ...)] 
  [PARTITIONED BY (col_name1, col_name2, ...)]
  [COMMENT table_comment]
  [AS select_statement]

Keywords

• IF NOT EXISTS: Prevents system errors when the created table exists.
• USING: Storage format.
• OPTIONS: Property name and property value when a table is created.
• COMMENT: Field or table description.
• PARTITIONED BY: Partition field.
• AS: Run the CREATE TABLE AS statement to create a table.

Parameters

Example 1: Creating an OBS Non-Partitioned Table

Example description: Create an OBS non-partitioned table named table1 and use the USING keyword to set the storage format of the table to orc.

You can store OBS tables in parquet, json, or avro format.

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CREATE TABLE IF NOT EXISTS table1 (
    col_1   STRING,
    col_2   INT)
USING orc
OPTIONS (path 'obs://bucketName/filePath');

Example 2: Creating an OBS Partitioned Table

Example description: Create a partitioned table named student. The partitioned table is partitioned using facultyNo and classNo. The student table is partitioned by faculty number (facultyNo) and class number (classNo).

In practice, you can select a proper partitioning field and add it to the brackets following the PARTITIONED BY keyword.

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CREATE TABLE IF NOT EXISTS student (
    Name        STRING,
    facultyNo   INT,
    classNo     INT)
USING csv
OPTIONS (path 'obs://bucketName/filePath')
PARTITIONED BY (facultyNo, classNo);

Example 3: Using CTAS to Create an OBS Non-Partitioned Table Using All or Part of the Data in the Source Table

Example description: Based on the OBS table table1 created in Example 1: Creating an OBS Non-Partitioned Table, use the CTAS syntax to copy data from table1 to table1_ctas.

When using CTAS to create a table, you can ignore the syntax used to create the table being copied. This means that regardless of the syntax used to create table1, you can use the DataSource syntax to create table1_ctas.

In addition, in this example, the storage format of table1 is orc, and the storage format of table1_ctas may be parquet. This means that the storage format of the table created by CTAS may be different from that of the original table.

Use the SELECT statement following the AS keyword to select required data and insert the data to table1_ctas.

The SELECT syntax is as follows: SELECT <Column name > FROM <Table name > WHERE <Related filter criteria>.

• In this example, SELECT * FROM table1 is used. * indicates that all columns are selected from table1 and all data in table1 is inserted into table1_ctas.

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  CREATE TABLE IF NOT EXISTS table1_ctas USING parquet OPTIONS (path 'obs:// bucketName/filePath') AS SELECT * FROM table1;

• To filter and insert data into table1_ctas in a customized way, you can use the following SELECT statement: SELECT col_1 FROM table1 WHERE col_1 = 'Ann'. This will allow you to select only col_1 from table1 and insert data into table1_ctas where the value equals 'Ann'.

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  CREATE TABLE IF NOT EXISTS table1_ctas USING parquet OPTIONS (path 'obs:// bucketName/filePath') AS SELECT col_1 FROM table1 WHERE col_1 = 'Ann';

Example 4: Creating an OBS Non-Partitioned Table and Customizing the Data Type of a Column Field

Example description: Create an OBS non-partitioned table named table2. You can customize the native data types of column fields based on service requirements.

• STRING, CHAR, or VARCHAR can be used for text characters.
• TIMESTAMP or DATE can be used for time characters.
• INT, SMALLINT/SHORT, BIGINT/LONG, or TINYINT can be used for integer characters.
• FLOAT, DOUBLE, or DECIMAL can be used for decimal calculation.
• BOOLEAN can be used if only logical switches are involved.

For details, see "Data Types" > "Primitive Data Types".

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CREATE TABLE IF NOT EXISTS table2 (
    col_01  STRING,
    col_02  CHAR (2),
    col_03  VARCHAR (32),
    col_04  TIMESTAMP,
    col_05  DATE,
    col_06  INT,
    col_07  SMALLINT,
    col_08  BIGINT,
    col_09  TINYINT,
    col_10  FLOAT,
    col_11  DOUBLE,
    col_12  DECIMAL (10, 3),
    col_13  BOOLEAN
)
USING parquet
OPTIONS (path 'obs://bucketName/filePath');

Example 5: Creating an OBS Partitioned Table and Customizing OPTIONS Parameters

Example description: When creating an OBS table, you can customize property names and values. For details about OPTIONS parameters, see Table 2.

In this example, an OBS partitioned table named table3 is created and partitioned based on col_2. Configure path, multiLevelDirEnable, dataDelegated, and compression in OPTIONS.

• path: OBS storage path. In this example, the value is obs://bucketName/filePath, where bucketName indicates the bucket name and filePath indicates the actual directory name.
• In big data scenarios, you are advised to use the OBS parallel file system for storage.
• multiLevelDirEnable: In this example, set this parameter to true, indicating that all files and subdirectories in the table path are read iteratively when the table is queried. If this parameter is not required, set it to false or leave it blank (the default value is false).
• dataDelegated: In this example, set this parameter to true, indicating that all data in the path is deleted when a table or partition is deleted. If this parameter is not required, set it to false or leave it blank (the default value is false).
• compression: If the created OBS table needs to be compressed, you can use the keyword compression to configure the compression format. In this example, the zstd compression format is used.

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CREATE TABLE IF NOT EXISTS table3 (
    col_1   STRING,
    col_2   int
)
USING parquet
PARTITIONED BY (col_2)
OPTIONS (
    path 'obs://bucketName/filePath',
    multiLeveldirenable = true,
    datadelegated = true,
    compression = 'zstd'
);

Example 6: Creating an OBS Non-Partitioned Table and Customizing OPTIONS Parameters

Example description: A CSV table is a file format that uses commas to separate data values in plain text. It is commonly used for storing and sharing data, but it is not ideal for complex data types due to its lack of structured data concepts. So, when file_format is set to csv, more OPTIONS parameters can be configured. For details, see Table 3.

In this example, a non-partitioned table named table4 is created with a csv storage format, and additional OPTIONS parameters are used to constrain the data.

• delimiter: data separator, indicating that commas (,) are used as separators between data
• quote: quotation character, indicating that double quotation marks (") are used to quota the reference information in the data
• escape: escape character, indicating that backslashes (\) are used as the escape character for data storage
• multiLine: This parameter is used to set the column data to be stored does not include carriage return or newline characters.
• dataFormat: indicates that the date format of the data field in the CSV file is yyyy-MM-dd.
• timestamoFormat: indicates that the timestamp format in the CSV file is yyyy-MM-dd HH:mm:ss.
• header: indicates that the CSV table contains the table header information.
• nullValue: indicates that null is set to indicate the null value in the CSV table.
• comment: indicates that the CSV table uses a slash (/) to indicate the beginning of a comment.
• compression: indicates that the CSV table is compressed in the gzip, bzip2, or deflate format. If compression is not required, set this parameter to none.
• encoding: indicates that the table uses the utf-8 encoding format. You can choose utf-8, gb2312, or gbk as needed. The default encoding format is utf-8.

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CREATE TABLE IF NOT EXISTS table4 (
    col_1 STRING,
    col_2 INT
)
USING csv
OPTIONS (
    path 'obs://bucketName/filePath',
    delimiter       = ',',
    quote            = '#',
    escape           = '|',
    multiline        = false,
    dateFormat       = 'yyyy-MM-dd',
    timestampFormat  = 'yyyy-MM-dd HH:mm:ss',
    mode             = 'failfast',
    header           = true,
    nullValue        = 'null',
    comment          = '*',
    compression      = 'deflate',
    encoding         = 'utf - 8'
);