Kim Jin Chul has posted comments on this change. ( http://gerrit.cloudera.org:8080/8851 )
Change subject: IMPALA-3193: Show table's comment on show tables ...................................................................... Patch Set 4: (1 comment) http://gerrit.cloudera.org:8080/#/c/8851/4/fe/src/main/java/org/apache/impala/service/JniFrontend.java File fe/src/main/java/org/apache/impala/service/JniFrontend.java: http://gerrit.cloudera.org:8080/#/c/8851/4/fe/src/main/java/org/apache/impala/service/JniFrontend.java@304 PS4, Line 304: for (Table table: tables) { : org.apache.hadoop.hive.metastore.api.Table msTable : = table.getMetaStoreTable(msClient); : if (msTable != null) { : String comment = msTable.getParameters().get("comment"); : comments.add(comment != null ? comment : ""); : } : } > The catalog server is the only entity responsible for loading metadata and Okay, I have a concern before providing a new patch set using your approach. If I understand correctly, you meant "comment can be empty even though user gives a comment because any HMS call is not allowed here". I have some comments on this. 1. I don't have an idea how I make a valid test case because we cannot guarantee showing comments. Do you have an idea? 2. As far as I understand HMS object cache is a subset of catalog cache because Catalog.Table can keep msTable. I think this is a kind of catalog cache. Am I wrong? Would you please explain the purpose of catalog cache briefly if I don't know about? 3. End user expects to see a given comment when he/she creates a table. User may raise an issue if the comment is not visible. What do you think about that? 4. I agree any HMS call pays some costs, but I think this happens only in show tables and HMS call happens only once for each table. If you still think this approach is time critical issue and worry about this, what do you think about approach? Syntax extension: adding a new option(e.g SHOW TABLES [WITH COMMENTS] [...]). -- To view, visit http://gerrit.cloudera.org:8080/8851 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: I44f814af05db6f3c027718ade9f474f8b8153bcd Gerrit-Change-Number: 8851 Gerrit-PatchSet: 4 Gerrit-Owner: Kim Jin Chul <[email protected]> Gerrit-Reviewer: Dimitris Tsirogiannis <[email protected]> Gerrit-Reviewer: Kim Jin Chul <[email protected]> Gerrit-Comment-Date: Tue, 09 Jan 2018 10:34:27 +0000 Gerrit-HasComments: Yes
