Hi dev:
Currently the 'comment' content for column is ambiguous and unclear when
execute command 'desc formatted table_name', for example:
ran create table sql:
CREATE TABLE IF NOT EXISTS test_table (
id INT,
name STRING,
city STRING,
salary LONG,
tax DOUBLE
)
STORED BY 'carbondata'
TBLPROPERTIES(
'streaming'='false', 'sort_columns'='name,id',
'dictionary_include'='name');
and then ran 'desc formatted test_table', it showed the content below:
|col_name |data_type |comment |
+----------+--------------+--------------------------------------------+
|id |int |KEY COLUMN,NOINVERTEDINDEX,null |
|name |string |DICTIONARY, KEY COLUMN,null |
|city |string |KEY COLUMN,null |
|salary |bigint |MEASURE,null |
|tax |double |MEASURE,null |
| | | |
1. what's the 'KEY COLUMN' mean? all document do not describe this
concept, just introduce dimension column, measure column, inverted index,
dictionary column and so on.
2. Actually 'city' field is just a dimension column and does not have
inverted index, but 'id', 'name' and 'city' field are shown as 'KEY COLUMN',
how to distinguish between them?
So IMO, We can show more detailed information on 'comment' column and
remove 'KEY COLUMN' description, for example:
run 'desc formatted test_table', it can show the content below:
|col_name |data_type |comment |
+----------+--------------+--------------------------------------------+
|id |int |DIMENSION,NOINVERTEDINDEX,null |
|name |string |DIMENSION,DICTIONARY,INVERTEDINDEX,null |
|city |string |DIMENSION,null |
|salary |bigint |MEASURE,null |
|tax |double |MEASURE,null |
| | | |
How about this change? Any suggestion for this? Please let me know.
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