[ 
https://issues.apache.org/jira/browse/DRILL-4826?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15507514#comment-15507514
 ] 

ASF GitHub Bot commented on DRILL-4826:
---------------------------------------

Github user gparai commented on a diff in the pull request:

    https://github.com/apache/drill/pull/592#discussion_r79689068
  
    --- Diff: 
exec/java-exec/src/main/java/org/apache/drill/exec/ExecConstants.java ---
    @@ -291,6 +291,9 @@
       String ENABLE_BULK_LOAD_TABLE_LIST_KEY = 
"exec.enable_bulk_load_table_list";
       BooleanValidator ENABLE_BULK_LOAD_TABLE_LIST = new 
BooleanValidator(ENABLE_BULK_LOAD_TABLE_LIST_KEY, false);
     
    +  String BULK_LOAD_TABLE_LIST_BULK_SIZE_KEY = 
"exec.bulk_load_table_list.bulk_size";
    --- End diff --
    
    Maybe a comment to describe the option?


> Query against INFORMATION_SCHEMA.TABLES degrades as the number of views 
> increases
> ---------------------------------------------------------------------------------
>
>                 Key: DRILL-4826
>                 URL: https://issues.apache.org/jira/browse/DRILL-4826
>             Project: Apache Drill
>          Issue Type: Bug
>            Reporter: Parth Chandra
>            Assignee: Parth Chandra
>
> Queries against INFORMATION_SCHEMA.TABLES and INFORMATION_SCHEMA.VIEWS slow 
> down as the number of views increases. 
> BI tools like Tableau issue a query like the following at connection time:
> {code}
> select TABLE_CATALOG, TABLE_SCHEMA, TABLE_NAME, TABLE_TYPE from 
> INFORMATION_SCHEMA.`TABLES` WHERE TABLE_CATALOG LIKE 'DRILL' ESCAPE '\' AND 
> TABLE_SCHEMA <> 'sys' AND TABLE_SCHEMA <> 'INFORMATION_SCHEMA'ORDER BY 
> TABLE_TYPE, TABLE_CATALOG, TABLE_SCHEMA, TABLE_NAME
> {code}
> The time to query the information schema tables degrades as the number of 
> views increases. On a test system:
> || Views || Time(secs) ||
> |500 | 6 |
> |1000 | 19 |
> |1500 | 33 |
> This can result in a single connection taking more than a minute to establish.
> The problem occurs because we read the view file for every view and this 
> appears to take most of the time.
> Querying information_schema.tables does not, in fact, need to open the view 
> file at all, it merely needs to get a listing of the view files. Eliminating 
> the view file read will speed up the query tremendously.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

Reply via email to