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### What changes were proposed in this pull request? Improve the CREATE TABLE document: 1. mention that some clauses can come in as any order. 2. refine the description for some parameters. 3. mention how data source table interacts with data source 4. make the examples consistent between data source and hive serde tables. ### Why are the changes needed? improve doc ### Does this PR introduce any user-facing change? no ### How was this patch tested? N/A Closes #27638 from cloud-fan/doc. Authored-by: Wenchen Fan <wenchen@databricks.com> Signed-off-by: Wenchen Fan <wenchen@databricks.com>
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| layout | title | displayTitle | license |
|---|---|---|---|
| global | CREATE HIVEFORMAT TABLE | CREATE HIVEFORMAT TABLE | Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. |
Description
The CREATE TABLE statement defines a new table using Hive format.
Syntax
{% highlight sql %} CREATE [ EXTERNAL ] TABLE [ IF NOT EXISTS ] table_identifier [ ( col_name1[:] col_type1 [ COMMENT col_comment1 ], ... ) ] [ COMMENT table_comment ] [ PARTITIONED BY ( col_name2[:] col_type2 [ COMMENT col_comment2 ], ... ) | ( col_name1, col_name2, ... ) ] [ ROW FORMAT row_format ] [ STORED AS file_format ] [ LOCATION path ] [ TBLPROPERTIES ( key1=val1, key2=val2, ... ) ] [ AS select_statement ]
{% endhighlight %}
Note that, the clauses between the columns definition clause and the AS SELECT clause can come in as any order. For example, you can write COMMENT table_comment after TBLPROPERTIES.
Parameters
table_identifier-
Specifies a table name, which may be optionally qualified with a database name.
Syntax:[ database_name. ] table_name
EXTERNAL- Table is defined using the path provided as LOCATION, does not use default location for this table.
PARTITIONED BY- Partitions are created on the table, based on the columns specified.
ROW FORMAT- SERDE is used to specify a custom SerDe or the DELIMITED clause in order to use the native SerDe.
STORED AS- File format for table storage, could be TEXTFILE, ORC, PARQUET,etc.
LOCATION- Path to the directory where table data is stored, Path to the directory where table data is stored, which could be a path on distributed storage like HDFS, etc.
COMMENT- A string literal to describe the table.
TBLPROPERTIES- A list of key-value pairs that is used to tag the table definition.
AS select_statement- The table is populated using the data from the select statement.
Examples
{% highlight sql %}
--Use hive format CREATE TABLE student (id INT, name STRING, age INT) STORED AS ORC;
--Use data from another table CREATE TABLE student_copy STORED AS ORC AS SELECT * FROM student;
--Specify table comment and properties CREATE TABLE student (id INT, name STRING, age INT) COMMENT 'this is a comment' STORED AS ORC TBLPROPERTIES ('foo'='bar');
--Specify table comment and properties with different clauses order CREATE TABLE student (id INT, name STRING, age INT) STORED AS ORC TBLPROPERTIES ('foo'='bar') COMMENT 'this is a comment';
--Create partitioned table CREATE TABLE student (id INT, name STRING) PARTITIONED BY (age INT) STORED AS ORC;
--Create partitioned table with different clauses order CREATE TABLE student (id INT, name STRING) STORED AS ORC PARTITIONED BY (age INT);
--Use Row Format and file format CREATE TABLE student (id INT,name STRING) ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' STORED AS TEXTFILE;
{% endhighlight %}