[SPARK-29539][SQL] SHOW PARTITIONS should look up catalog/table like v2 commands

[huaxingao]

What changes were proposed in this pull request?

Add ShowPartitionsStatement and make SHOW PARTITIONS go through the same catalog/table resolution framework of v2 commands.

Why are the changes needed?

It's important to make all the commands have the same table resolution behavior, to avoid confusing end-users.

Does this PR introduce any user-facing change?

Yes. When running SHOW PARTITIONS, Spark fails the command if the current catalog is set to a v2 catalog, or the table name specified a v2 catalog.

How was this patch tested?

Unit tests.

[huaxingao]

@viirya
Could you please review? Thanks a lot!

[viirya]

This looks fine to me. Looks like loadTable can provide partitioning info so V2 implementation can also be implemented now? @cloud-fan @rdblue

[rdblue]

This looks fine to me. Looks like loadTable can provide partitioning info so V2 implementation can also be implemented now?

The partitioning provided by loadTable are the transforms and partition columns, not the actual table partitions. SHOW PARTITIONS can't be implemented until we have an API for getting partition metadata.

[viirya]

Let's add a case of a.b.c.

[huaxingao]

Thanks @viirya for your review. The comment has been addressed.

[SparkQA]

Test build #112414 has finished for PR 26198 at commit 003ab44.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
• case class ShowPartitionsStatement(tableName: Seq[String],

[SparkQA]

Test build #112436 has finished for PR 26198 at commit 157b755.

• This patch fails due to an unknown error code, -9.
• This patch merges cleanly.
• This patch adds no public classes.

[cloud-fan]

the changes LGTM, let's fix the conflict

[SparkQA]

Test build #112478 has finished for PR 26198 at commit 248513c.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[huaxingao]

Conflicts fixed @viirya

[viirya]

Thanks. Merging this to master!

[huaxingao]

Thanks all for the help!