Implement COMMENT ON COLUMN in JDBC based connector

[ebyhr]

• ClickHouse Support setting column comments in ClickHouse #10641
• Druid (not supported)
• MemSQL (@shandeep00)
  https://docs.memsql.com/v7.1/reference/sql-reference/data-definition-language-ddl/alter-table/
• MySQL (Implement COMMENT ON COLUMN in MySQL #5383)
  https://dev.mysql.com/doc/refman/8.0/en/alter-table.html
• Oracle (Add support for COMMENT ON COLUMN in Oracle connector #5399)
  https://docs.oracle.com/cd/B19306_01/server.102/b14200/statements_4009.htm
• Phoenix (not supported)
• PostgreSQL (Add support for setting column comment in PostgreSQL #5307)
• Redshift (Add COMMENT ON COLUMN support for Redshift Connector #5397)
  https://docs.aws.amazon.com/redshift/latest/dg/r_COMMENT.html
• SQL Server
  https://docs.microsoft.com/en-us/sql/relational-databases/system-stored-procedures/sp-addextendedproperty-transact-sql?view=sql-server-ver15
  reminder: SQL Server JDBC driver isn't exposing a comment via REMARKS column

[agrawalreetika]

@ebyhr, I would like to work on this. Could you please let me know if the issue is different from #5334?

[ebyhr]

@agrawalreetika While #5334 is for CREATE TABLE, this ticket's objective is supporting COMMENT ON COLUMN. I think this ticket is easier than #5334.

[shandeep00]

@ebyhr @agrawalreetika anyone working on support for Mysql?

[agrawalreetika]

@shandeep00 I have started looking into changes for implementing comment on a column in MySQL, will raise PR soon

[shandeep00]

cool, maybe this can help u started, https://www.tutorialspoint.com/How-can-we-use-MySQL-ALTER-TABLE-command-for-adding-comments-on-columns

[Riddle4045]

@ebyhr is the work for SQL server done? if not i'd be happy to take it!

[ebyhr]

@Riddle4045 Not yet. You can take it freely, but please note that:

• SQL Server doesn't expose column comment via REMARKS result set. We will need to introduce a flag not to decrease the performance for metadata fetching.
• You need to find how to create CREATE TABLE with column comments in SQL Server

[Riddle4045]

@ebyhr Thanks, I browsed through microsoft/mssql-jdbc#646, Looks like Microsoft does not intend to add support for REMARKS in the jdbc driver. This would mean we use extended properties for retrieving comments and multiple calls ( again through extended properties ) to support CREATE TABLE with column comments. I doubt that this feature should take up the estimated complexity budget for the connector, what do you think?