Csaba Ringhofer has posted comments on this change. ( http://gerrit.cloudera.org:8080/14021 )
Change subject: IMPALA-8811 IMPALA-8813: [DOCS] Document the ACID support in Impala ...................................................................... Patch Set 6: (2 comments) http://gerrit.cloudera.org:8080/#/c/14021/6/docs/topics/impala_default_transactional_type.xml File docs/topics/impala_default_transactional_type.xml: http://gerrit.cloudera.org:8080/#/c/14021/6/docs/topics/impala_default_transactional_type.xml@58 PS6, Line 58: The : <codeph>INSERT</codeph> operations will be transactional on this table. I think that the best thing here would be a link to impala_transactions. http://gerrit.cloudera.org:8080/#/c/14021/5/docs/topics/impala_transactions.xml File docs/topics/impala_transactions.xml: http://gerrit.cloudera.org:8080/#/c/14021/5/docs/topics/impala_transactions.xml@35 PS5, Line 35: satisfy a level of ACID (Atomicity, Consistency, Isolation, Durability) properties, which > Slightly reworded. I totally agree with Tim, we should think it through carefully what to write here. What Impala should profit from Hive ACID at the moment is that a single table insert from Hive/Impala is either completely seen or not seen at all during a query (without ACID if an insert create more than one files, it was possible to list the files at the "wrong moment" when only some of them were copied to their final destination from the staging directory), and for a single table the inserts are "ordered", so if Impala doesn't see a committed insert, it won't see any insert committed after it. On the other side for different tables Impala can have snapshots from totally different times, so it may see a commit on table A while not see a much earlier commit on table B. This should not happen when reading with Hive. -- To view, visit http://gerrit.cloudera.org:8080/14021 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: I0320e573301175dedb00d6e745f9f973519a16bb Gerrit-Change-Number: 14021 Gerrit-PatchSet: 6 Gerrit-Owner: Alex Rodoni <[email protected]> Gerrit-Reviewer: Alex Rodoni <[email protected]> Gerrit-Reviewer: Attila Jeges <[email protected]> Gerrit-Reviewer: Csaba Ringhofer <[email protected]> Gerrit-Reviewer: Greg Rahn <[email protected]> Gerrit-Reviewer: Impala Public Jenkins <[email protected]> Gerrit-Reviewer: Lars Volker <[email protected]> Gerrit-Reviewer: Tamas Mate <[email protected]> Gerrit-Reviewer: Tim Armstrong <[email protected]> Gerrit-Reviewer: Todd Lipcon <[email protected]> Gerrit-Reviewer: Zoltan Borok-Nagy <[email protected]> Gerrit-Comment-Date: Fri, 09 Aug 2019 20:44:36 +0000 Gerrit-HasComments: Yes
