### What changes were proposed in this pull request?
In Hive mode, permanent functions are shared with Hive metastore so that functions may be modified by other Hive client. With in long-lived spark scene, it's hard to update the change of function.
Here are 2 reasons:
* Spark cache the function in memory using `FunctionRegistry`.
* User may not know the location or classname of udf when using `replace function`.
Note that we use v2 command code path to add new command.
### Why are the changes needed?
Give a easy way to make spark function registry sync with Hive metastore.
Then we can call
```
refresh function functionName
```
### Does this PR introduce _any_ user-facing change?
Yes, new command.
### How was this patch tested?
New UT.
Closes#28840 from ulysses-you/SPARK-31999.
Authored-by: ulysses <youxiduo@weidian.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
### What changes were proposed in this pull request?
docs/sql-ref-syntax-qry-select-usedb.md -> docs/sql-ref-syntax-ddl-usedb.md
docs/sql-ref-syntax-aux-refresh-table.md -> docs/sql-ref-syntax-aux-cache-refresh-table.md
### Why are the changes needed?
usedb belongs to DDL. Its location should be consistent with other DDL commands file locations
similar reason for refresh table
### Does this PR introduce _any_ user-facing change?
before change, when clicking USE DATABASE, the side bar menu shows select commands
<img width="1200" alt="Screen Shot 2020-07-04 at 9 05 35 AM" src="https://user-images.githubusercontent.com/13592258/86516696-b45f8a80-bdd7-11ea-8dba-3a5cca22aad3.png">
after change, when clicking USE DATABASE, the side bar menu shows DDL commands
<img width="1120" alt="Screen Shot 2020-07-04 at 9 06 06 AM" src="https://user-images.githubusercontent.com/13592258/86516703-bf1a1f80-bdd7-11ea-8a90-ae7eaaafd44c.png">
before change, when clicking refresh table, the side bar menu shows Auxiliary statements
<img width="1200" alt="Screen Shot 2020-07-04 at 9 30 40 AM" src="https://user-images.githubusercontent.com/13592258/86516877-3d2af600-bdd9-11ea-9568-0a6f156f57da.png">
after change, when clicking refresh table, the side bar menu shows Cache statements
<img width="1199" alt="Screen Shot 2020-07-04 at 9 35 21 AM" src="https://user-images.githubusercontent.com/13592258/86516937-b4f92080-bdd9-11ea-8ad1-5f5a7f58d76b.png">
### How was this patch tested?
Manually build and check
Closes#28995 from huaxingao/docs_fix.
Authored-by: Huaxin Gao <huaxing@us.ibm.com>
Signed-off-by: Huaxin Gao <huaxing@us.ibm.com>
2020-07-04 19:01:07 -07:00
Renamed from docs/sql-ref-syntax-aux-refresh-table.md (Browse further)
