Dimitris Tsirogiannis 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 : ""); : } : } > Regarding your suggestion, there was no loaded tables when I attached debug The catalog server is the only entity responsible for loading metadata and making calls to HMS (for that purpose). On the other hand, Impalad's catalog cache should not be doing anything like that (which is what you do in this block). JniFronted::getTableNames() retrieves and returns the names of tables that the local catalog cache knows of (no external communication with either the catalog server or the HMS). So, what you should do is the following: If the table is fully loaded and has a comment, you can retrieve it directly from the Table object. If the table is not fully loaded, you don't do anything (return empty string) even if the table has a comment stored in HMS. If the table is loaded but has no comment, return an empty string. If the concepts of fully loaded metadata, catalog server and impalad catalog cache are not clear, I suggest you spend some time at the code before working on this change. Impala's metadata management system is a bit complex, so it takes some time to grasp all the details and the information flow. -- 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 <jinc...@gmail.com> Gerrit-Reviewer: Dimitris Tsirogiannis <dtsirogian...@cloudera.com> Gerrit-Reviewer: Kim Jin Chul <jinc...@gmail.com> Gerrit-Comment-Date: Mon, 08 Jan 2018 18:34:05 +0000 Gerrit-HasComments: Yes
