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 : ""); : } : } > Okay, I have a concern before providing a new patch set using your approach 1. You can guarantee that by forcing table metadata to be loaded for a table. A simple select statement or a refresh <tbl> statement would suffice. Then you can issue a show tables and see the comments for any loaded tables. 2. There are two catalog caches in Impala: a) catalog server (CatalogServiceCatalog.java) and b) local catalog cache (ImpaladCatalog.java) on every Impalad node. msTable is not a cache, it's simply the object returned by HMS that represents a table. 3. That's a limitation that users will have to leave with in the current design. 4. That cost is still too high. Let's not extend the syntax for the moment. Besides, it's not just show tables, there is also show databases. So, if we do something like that, we will have to do it for every show statement that returns an object 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 18:38:10 +0000 Gerrit-HasComments: Yes
