[GitHub] [spark] zhengruifeng commented on pull request #40276: [SPARK-42630][CONNECT][PYTHON] Implement data type string parser

["zhengruifeng (via GitHub)" <gi...@apache.org>]

zhengruifeng commented on PR #40276:
URL: https://github.com/apache/spark/pull/40276#issuecomment-1454583496

   I don't know the internal of Parser well, but I guess if we want to reach 100% compatibility, we may need to reuse the `.g4` files and implement a subset of  `AstBuilder` to support `singleDataType` and `singleTableSchema`.
   
   For example, the DDL also support `NOT NULL` and `COMMENT`:
   ```
   >>> df = spark.createDataFrame([], """a string  COMMENT 'this is just a simple string' """)
   >>> df.schema
   StructType([StructField('a', StringType(), True)])
   >>> df = spark.createDataFrame([], """a string  NOT NULL COMMENT 'this is just a simple string' """)
   >>> df.schema
   StructType([StructField('a', StringType(), False)])
   ```
   
   cc @hvanhovell @cloud-fan @HyukjinKwon  WDYT?


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