Zoltan Borok-Nagy has posted comments on this change. ( http://gerrit.cloudera.org:8080/20077 )
Change subject: IMPALA-11013: Support 'MIGRATE TABLE' for external Hive tables ...................................................................... Patch Set 5: (1 comment) http://gerrit.cloudera.org:8080/#/c/20077/5//COMMIT_MSG Commit Message: http://gerrit.cloudera.org:8080/#/c/20077/5//COMMIT_MSG@11 PS5, Line 11: an external table > I don't think that we can use 'non-transactional table' as a synonym for 'e Hive 3 defined external tables as non-transactional tables. I personally don't like it, but unfortunately it is what it is. There are a lot of assumptions in Hive/Impala code that they are equal. Altering a non-transactional table in a way to set EXTERNAL table property to false creates an invalid table and will cause subtle errors. It is like undefined behavior in C++. E.g. try to insert something into such a table then query it. To me it returns invalid results. Hive also stores managed/external tables at different locations, and in some cases it checks whether the data files are under the managed/external table space. But let's assume we could set EXTERNAL to false and everything would work as expected. The current table migration logic could work well on such a table because it wouldn't have transactional state and wouldn't have special file schemas. So the point is, we don't allow migrating non-EXTERNAL tables because we assume that they are transactional and need special care. -- To view, visit http://gerrit.cloudera.org:8080/20077 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: Iacdad996d680fe545cc9a45e6bc64a348a64cd80 Gerrit-Change-Number: 20077 Gerrit-PatchSet: 5 Gerrit-Owner: Gabor Kaszab <[email protected]> Gerrit-Reviewer: Anonymous Coward <[email protected]> Gerrit-Reviewer: Gabor Kaszab <[email protected]> Gerrit-Reviewer: Impala Public Jenkins <[email protected]> Gerrit-Reviewer: Tamas Mate <[email protected]> Gerrit-Reviewer: Zoltan Borok-Nagy <[email protected]> Gerrit-Comment-Date: Wed, 28 Jun 2023 09:33:38 +0000 Gerrit-HasComments: Yes
