Zoltan Borok-Nagy has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/15797 )

Change subject: IMPALA-9688: Support create iceberg table by impala
......................................................................


Patch Set 19:

(1 comment)

Thanks for applying the changes. LGTM, however still have some concerns about 
"file system tables"/"metastore tables".

http://gerrit.cloudera.org:8080/#/c/15797/17/fe/src/main/java/org/apache/impala/util/IcebergUtil.java
File fe/src/main/java/org/apache/impala/util/IcebergUtil.java:

http://gerrit.cloudera.org:8080/#/c/15797/17/fe/src/main/java/org/apache/impala/util/IcebergUtil.java@24
PS17, Line 24: import org.apache.iceberg.hadoop.HadoopTableOperations;
             : import org.apache.iceberg.hadoop.HadoopTables;
> Iceberg indeed support HiveCatalog and HadoopTables to create 'Metastore ta
"if we use HiveCatalog to create a metastore table, we cannot create external 
table by impala, because there is already a table in hms created by iceberg."

In that case there would be no need to create the table in Impala, just do an 
"invalidate metadata" and Impala should see the table.

>From HMS point of view Iceberg tables will always be external. From Hive 3 or 
>4, only Hive ACID tables can be managed tables. And there are two kinds of 
>external tables based on the 'external.table.purge' property. If this property 
>is true, DROP TABLE must also remove the data files. If false, DROP table only 
>removes the table from HMS.

My other concern related to "File System Tables" is that they require atomic 
rename operation from the underlying filesystem, therefore we cannot really use 
these on S3.



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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: I8d85db4c904a8c758c4cfb4f19cfbdab7e6ea284
Gerrit-Change-Number: 15797
Gerrit-PatchSet: 19
Gerrit-Owner: wangsheng <[email protected]>
Gerrit-Reviewer: Impala Public Jenkins <[email protected]>
Gerrit-Reviewer: Sahil Takiar <[email protected]>
Gerrit-Reviewer: Zoltan Borok-Nagy <[email protected]>
Gerrit-Reviewer: wangsheng <[email protected]>
Gerrit-Comment-Date: Tue, 12 May 2020 16:12:28 +0000
Gerrit-HasComments: Yes

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