HDFS Readable and Writable External Table Examples
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HDFS Readable and Writable External Table Examples
The following code defines a readable external table for an HDFS file named filename.txt on port 8081.
=# CREATE EXTERNAL TABLE ext_expenses ( name text, date date, amount float4, category text, desc1 text ) LOCATION ('gphdfs://hdfshost-1:8081/data/filename.txt') FORMAT 'TEXT' (DELIMITER ',');
The following code defines a set of readable external tables that have a custom format located in the same HDFS directory on port 8081.
=# CREATE EXTERNAL TABLE ext_expenses ( name text, date date, amount float4, category text, desc1 text ) LOCATION ('gphdfs://hdfshost-1:8081/data/custdat*.dat') FORMAT 'custom' (formatter='gphdfs_import');
The following code defines an HDFS directory for a writable external table on port 8081 with all compression options specified.
=# CREATE WRITABLE EXTERNAL TABLE ext_expenses ( name text, date date, amount float4, category text, desc1 text ) LOCATION ('gphdfs://hdfshost-1:8081/data/?compress=true&compression_type=RECORD &codec=org.apache.hadoop.io.compress.DefaultCodec') FORMAT 'custom' (formatter='gphdfs_export');
Because the previous code uses the default compression options for compression_type and codec, the following command is equivalent.
=# CREATE WRITABLE EXTERNAL TABLE ext_expenses ( name text, date date, amount float4, category text, desc1 text ) LOCATION ('gphdfs://hdfshost-1:8081/data?compress=true') FORMAT 'custom' (formatter='gphdfs_export');