[jira] [Commented] (HIVE-4235) CREATE TABLE IF NOT EXISTS uses inefficient way to check if table exists

["Gang Tim Liu (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-4235?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13614649#comment-13614649 ] 

Gang Tim Liu commented on HIVE-4235:
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https://reviews.facebook.net/D9729
                
> CREATE TABLE IF NOT EXISTS uses inefficient way to check if table exists
> ------------------------------------------------------------------------
>
>                 Key: HIVE-4235
>                 URL: https://issues.apache.org/jira/browse/HIVE-4235
>             Project: Hive
>          Issue Type: Bug
>          Components: JDBC, Query Processor, SQL
>            Reporter: Gang Tim Liu
>            Assignee: Gang Tim Liu
>         Attachments: HIVE-4235.patch.1
>
>
> CREATE TABLE IF NOT EXISTS uses inefficient way to check if table exists.
> It uses Hive.java's getTablesByPattern(...) to check if table exists. It involves regular expression and eventually database join. Very efficient. It can cause database lock time increase and hurt db performance if a lot of such commands hit database.
> The suggested approach is to use getTable(...) since we know tablename already

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