[jira] [Commented] (HIVE-24693) Parquet Timestamp Values Read/Write Very Slow

["Karen Coppage (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-24693?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17276566#comment-17276566 ] 

Karen Coppage commented on HIVE-24693:
--------------------------------------

[~belugabehr] Per the the Wiki, Hive can handle years 0001-9999. However it doesn't really complain about years outside of that range. I once tried to get Hive to enforce this range but didn't get very far. FYI :)

BTW let me know if/when you want a review!

> Parquet Timestamp Values Read/Write Very Slow
> ---------------------------------------------
>
>                 Key: HIVE-24693
>                 URL: https://issues.apache.org/jira/browse/HIVE-24693
>             Project: Hive
>          Issue Type: Improvement
>            Reporter: David Mollitor
>            Assignee: David Mollitor
>            Priority: Critical
>              Labels: pull-request-available
>          Time Spent: 0.5h
>  Remaining Estimate: 0h
>
> Parquet {{DataWriteableWriter}} relias on {{NanoTimeUtils}} to convert a timestamp object into a binary value.  The way in which it does this,... it calls {{toString()}} on the timestamp object, and then parses the String.  This particular timestamp do not carry a timezone, so the string is something like:
> {{2021-21-03 12:32:23.0000...}}
> The parse code tries to parse the string assuming there is a time zone, and if not, falls-back and applies the provided "default time zone".  As was noted in [HIVE-24353], if something fails to parse, it is very expensive to try to parse again.  So, for each timestamp in the Parquet file, it:
> * Builds a string from the time stamp
> * Parses it (throws an exception, parses again)
> There is no need to do this kind of string manipulations/parsing, it should just be using the epoch millis/seconds/time stored internal to the Timestamp object.
> {code:java}
>   // Converts Timestamp to TimestampTZ.
>   public static TimestampTZ convert(Timestamp ts, ZoneId defaultTimeZone) {
>     return parse(ts.toString(), defaultTimeZone);
>   }
> {code}



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