Yann Byron

I am not sure if we can not support this sql command using `path`. If so, we don't need to extend the antlr grammar and sql parser and can reuse...

@zsxwing thanks for you explanation. I see delta defines the new output format for `show partitions` and that's nice.

I agree that this feature depends on changes in Spark. It involves adding keywords, overriding some visit functions in AstBuilder, and other UnResolved LogicalPlans for time-travel. But, we need to...

> @YannByron Feel free to raise a Spark issue to ask for the time travel SQL syntax support. https://issues.apache.org/jira/browse/SPARK-34978

OK, I'll try it as your suggestion. The current merge execution seems to skip all of the Optimizer's rules. If wanna support it, do you have some practicable idea?

@zsxwing if want to support creating table without schema provided, i think there is no necessary to introduce our own serde. maybe just a minor optimization for `DeltaStorageHandler.preCreateTable` is ok.

update: `metadata.Table` in Hive force to ask users to provide at least one column. And can't find any configure to skip this check. https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/metadata/Table.java L263. if this is the fact,...

@xushiyan @prasannarajaperumal @alexeykudinkin please continue to review this. and i will submit a following commit that use the avro format, not json format, to persist the fields.

@rjmblc some points which maybe cause this issue: 1. do you provide the configs `spark.sql.extensions=org.apache.spark.sql.hudi.HoodieSparkSessionExtension` and `"spark.sql.catalog.spark_catalog=org.apache.spark.sql.hudi.catalog.HoodieCatalog` 2. Can you not set this `client_id ` field as the primary key...

@huzk8 please give the whole stack trace to help me address this. and maybe you should use the `catalog.database.table` format to insert into, not `mysql.st` which only have catalog and...