Are they consistent with the current syntax defined in SqlBase.g4? I think we are following the Hive DDL syntax: https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DDL#LanguageManualDDL-AlterTable/Partition/Column
Ryan Blue <rb...@netflix.com.invalid> 于2018年9月28日周五 下午3:47写道： > Hi everyone, > > I’m currently working on new table DDL statements for v2 tables. For > context, the new logical plans for DataSourceV2 require a catalog interface > so that Spark can create tables for operations like CTAS. The proposed > TableCatalog API also includes an API for altering those tables so we can > make ALTER TABLE statements work. I’m implementing those DDL statements, > which will make it into upstream Spark when the TableCatalog PR is merged. > > Since I’m adding new SQL statements that don’t yet exist in Spark, I want > to make sure that the syntax I’m using in our branch will match the syntax > we add to Spark later. I’m basing this proposed syntax on PostgreSQL > <https://www.postgresql.org/docs/current/static/ddl-alter.html>. > > - *Update data type*: ALTER TABLE tableIdentifier ALTER COLUMN > qualifiedName TYPE dataType. > - *Rename column*: ALTER TABLE tableIdentifier RENAME COLUMN > qualifiedName TO qualifiedName > - *Drop column*: ALTER TABLE tableIdentifier DROP (COLUMN | COLUMNS) > qualifiedNameList > > A few notes: > > - Using qualifiedName in these rules allows updating nested types, > like point.x. > - Updates and renames can only alter one column, but drop can drop a > list. > - Rename can’t move types and will validate that if the TO name is > qualified, that the prefix matches the original field. > - I’m also changing ADD COLUMN to support adding fields to nested > columns by using qualifiedName instead of identifier. > > Please reply to this thread if you have suggestions based on a different > SQL engine or want this syntax to be different for another reason. Thanks! > > rb > -- > Ryan Blue > Software Engineer > Netflix >
