hive DDL

创建数据表

CREATE [EXTERNAL] TABLE [IF NOT EXISTS] table_name
  [(col_name data_type [COMMENT col_comment], ...)]
  [COMMENT table_comment]
  [PARTITIONED BY (col_name data_type [COMMENT col_comment], ...)]
  [CLUSTERED BY (col_name, col_name, ...) [SORTED BY (col_name [ASC|DESC], ...)] INTO num_buckets BUCKETS]
  [
   [ROW FORMAT row_format] [STORED AS file_format]
   | STORED BY 'storage.handler.class.name' [ WITH SERDEPROPERTIES (...) ]  (Note:  only available starting with 0.6.0)
  ]
  [LOCATION hdfs_path]
  [TBLPROPERTIES (property_name=property_value, ...)]  (Note:  only available starting with 0.6.0)
  [AS select_statement]  (Note: this feature is only available starting with 0.5.0.)

EXTERNAL配合LOCATION 一起使用。创建数据库时，为数据表指定位置。当需要删除EXTERNAL的数据表时，数据并不会从文件系统中删除。

CREATE [EXTERNAL] TABLE [IF NOT EXISTS] table_name
  LIKE existing_table_name
  [LOCATION hdfs_path]

LIKE根据一个已经存在的数据表，建立一个完全相同的表。但是不会拷贝其中的数据。

data_type
  : primitive_type
  | array_type
  | map_type
  | struct_type

primitive_type
  : TINYINT
  | SMALLINT
  | INT
  | BIGINT
  | BOOLEAN
  | FLOAT
  | DOUBLE
  | STRING

array_type
  : ARRAY < data_type >

map_type
  : MAP < primitive_type, data_type >

struct_type
  : STRUCT < col_name : data_type [COMMENT col_comment], ...>

row_format
  : DELIMITED [FIELDS TERMINATED BY char] [COLLECTION ITEMS TERMINATED BY char]
        [MAP KEYS TERMINATED BY char] [LINES TERMINATED BY char]
  | SERDE serde_name [WITH SERDEPROPERTIES (property_name=property_value, property_name=property_value, ...)]

file_format:
  : SEQUENCEFILE
  | TEXTFILE
  | RCFILE     (Note:  only available starting with 0.6.0)
  | INPUTFORMAT input_format_classname OUTPUTFORMAT output_format_classname