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From "Thomas Tauber-Marshall (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] IMPALA-5787: Dropped status in KuduTableSink::Send()
Date Mon, 14 Aug 2017 22:39:33 GMT
Thomas Tauber-Marshall has posted comments on this change.

Change subject: IMPALA-5787: Dropped status in KuduTableSink::Send()
......................................................................


Patch Set 1:

(1 comment)

http://gerrit.cloudera.org:8080/#/c/7667/1/be/src/exec/kudu-table-sink.cc
File be/src/exec/kudu-table-sink.cc:

PS1, Line 241:       // This can only fail if we set a col to an incorrect type, which would
be a bug in
             :       // planning, so we can DCHECK.
> can you check with the kudu developers (e.g. on the Kudu dev slack channel)
I checked with the Kudu team, and as long as the schema is what we want when the table is
opened, it should be fine. If the schema changes in an incompatible way after the table is
opened but before the writes are applied, the writes will fail gracefully at Appy().

However, there's a window of vulnerability between when we check the schema in the FE and
when the table object is opened, so I explored this in detail, and there are a few cases to
consider:
  
- Column type changes: we don't allow altering existing column's types.
- Column renamed: everything works as expected.
- Column added: we don't allow adding primary keys, and non-nullable columns that are added
must have a default, so everything works as expected.
- Column dropped: this causes a crash, with or without this change. I filed IMPALA-5799


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Gerrit-MessageType: comment
Gerrit-Change-Id: Ia228d98ca90de8638b0afcc242c788e225fb450f
Gerrit-PatchSet: 1
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Thomas Tauber-Marshall <tmarshall@cloudera.com>
Gerrit-Reviewer: Matthew Jacobs <mj@cloudera.com>
Gerrit-Reviewer: Thomas Tauber-Marshall <tmarshall@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <tarmstrong@cloudera.com>
Gerrit-HasComments: Yes

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