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  • greenplum利用外部表实现跨主机跨数据库类型查询

    CREATE EXTERNAL WEB TABLE testtable 
    (
      字段定义
    )
       EXECUTE 'mysql -hhost -uroot -ppassword -s -e "SELECT * FROM dbname.tablesname"' 
       ON MASTER
          FORMAT 'TEXT'

    上边是最终实现方法。下面简单说下实现依据

    官方文档有写:

    CREATE [READABLE] EXTERNAL WEB TABLE table_name     
       ( column_name data_type [, ...] | LIKE other_table )
          LOCATION ('http://webhost[:port]/path/file' [, ...])
        | EXECUTE 'command' [ON ALL 
                              | MASTER
                              | number_of_segments
                              | HOST ['segment_hostname'] 
                              | SEGMENT segment_id ]
          FORMAT 'TEXT' 
                [( [HEADER]
                   [DELIMITER [AS] 'delimiter' | 'OFF']
                   [NULL [AS] 'null string']
                   [ESCAPE [AS] 'escape' | 'OFF']
                   [NEWLINE [ AS ] 'LF' | 'CR' | 'CRLF']
                   [FILL MISSING FIELDS] )]
               | 'CSV'
                [( [HEADER]
                   [QUOTE [AS] 'quote'] 
                   [DELIMITER [AS] 'delimiter']
                   [NULL [AS] 'null string']
                   [FORCE NOT NULL column [, ...]]
                   [ESCAPE [AS] 'escape']
                   [NEWLINE [ AS ] 'LF' | 'CR' | 'CRLF']
                   [FILL MISSING FIELDS] )]
               | 'CUSTOM' (Formatter=<formatter specifications>)
         [ ENCODING 'encoding' ]
         [ [LOG ERRORS] SEGMENT REJECT LIMIT count
           [ROWS | PERCENT] ]

    剔除无用语法:

    CREATE EXTERNAL WEB TABLE table_name     
       ( column_name data_type [, ...] )
        EXECUTE 'command' 
         ON MASTER
          FORMAT 'TEXT'

    分隔符封闭符可以根据需要调整,最后根据业务调整为文章一开始那样的命令。

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  • 原文地址:https://www.cnblogs.com/chenminklutz/p/7365176.html
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