[jira] [Commented] (HIVE-13132) Hive should lazily load and cache metastore (permanent) functions

["Jason Dere (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-13132?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15174819#comment-15174819 ] 

Jason Dere commented on HIVE-13132:
-----------------------------------

It is true that HIVE-2573 still loads all permanent functions from all databases during startup. One thing that might improve things is HIVE-10319, which rather than calling once for every database, only makes a single call to the metastore to retrieve all permanent functions. Can you check if this helps at all?

> Hive should lazily load and cache metastore (permanent) functions
> -----------------------------------------------------------------
>
>                 Key: HIVE-13132
>                 URL: https://issues.apache.org/jira/browse/HIVE-13132
>             Project: Hive
>          Issue Type: Improvement
>    Affects Versions: 0.13.1
>            Reporter: Anthony Hsu
>            Assignee: Anthony Hsu
>         Attachments: HIVE-13132.1.patch
>
>
> In Hive 0.13.1, we have noticed that as the number of databases increases, the start-up time of the Hive interactive shell increases. This is because during start-up, all databases are iterated over to fetch the permanent functions to display in the {{SHOW FUNCTIONS}} output.
> {noformat:title=FunctionRegistry.java}
>   private static Set<String> getFunctionNames(boolean searchMetastore) {
>     Set<String> functionNames = mFunctions.keySet();
>     if (searchMetastore) {
>       functionNames = new HashSet<String>(functionNames);
>       try {
>         Hive db = getHive();
>         List<String> dbNames = db.getAllDatabases();
>         for (String dbName : dbNames) {
>           List<String> funcNames = db.getFunctions(dbName, "*");
>           for (String funcName : funcNames) {
>             functionNames.add(FunctionUtils.qualifyFunctionName(funcName, dbName));
>           }
>         }
>       } catch (Exception e) {
>         LOG.error(e);
>         // Continue on, we can still return the functions we've gotten to this point.
>       }
>     }
>     return functionNames;
>   }
> {noformat}
> Instead of eagerly loading all metastore functions, we should only load them the first time {{SHOW FUNCTIONS}} is invoked. We should also cache the results.
> Note that this issue may have been fixed by HIVE-2573, though I haven't verified this.



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