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1.7 KiB
1.7 KiB
hdfs
Creates a table from a file in HDFS.
hdfs(URI, format, structure)
Input parameters
URI
— The relative URI to the file in HDFS. Path to file support following globs in readonly mode:*
,?
,{abc,def}
and{N..M}
whereN
,M
— numbers, ``'abc', 'def'` — strings.format
— The format of the file.structure
— Structure of the table. Format'column1_name column1_type, column2_name column2_type, ...'
.
Returned value
A table with the specified structure for reading or writing data in the specified file.
Example
Table from hdfs://hdfs1:9000/test
and selection of the first two rows from it:
SELECT *
FROM hdfs('hdfs://hdfs1:9000/test', 'TSV', 'column1 UInt32, column2 UInt32, column3 UInt32')
LIMIT 2
┌─column1─┬─column2─┬─column3─┐
│ 1 │ 2 │ 3 │
│ 3 │ 2 │ 1 │
└─────────┴─────────┴─────────┘
Globs in path
*
— Matches any number of any characters including none.?
— Matches any single character.{some_string,another_string,yet_another_one}
— Matches any of strings'some_string', 'another_string', 'yet_another_one'
.{N..M}
— Matches any number in range from N to M including both borders.
!!! warning
If your listing of files contains number ranges with leading zeros, use the construction with braces for each digit separately or use ?
.
Multiple path components can have globs. For being processed file should exists and matches to the whole path pattern.