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https://issues.apache.org/jira/browse/DRILL-4826?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15507217#comment-15507217
 ] 

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

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

    https://github.com/apache/drill/pull/592#discussion_r79665593
  
    --- Diff: 
exec/java-exec/src/main/java/org/apache/drill/exec/store/ischema/InfoSchemaRecordGenerator.java
 ---
    @@ -55,6 +54,7 @@
      * schema, table or field.
      */
     public abstract class InfoSchemaRecordGenerator {
    +  static final org.slf4j.Logger logger = 
org.slf4j.LoggerFactory.getLogger(InfoSchemaRecordGenerator.class);
    --- End diff --
    
    private


> 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.



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