[
https://issues.apache.org/jira/browse/HIVE-1629?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12908210#action_12908210
]
Vaibhav Aggarwal commented on HIVE-1629:
----------------------------------------
Hi
The doubleToLongBits converts the double value into IEEE 754 floating-point
"double format" bit layout.
Furthermore the XOR operator prevents returning 0 for values less than 2^32.
This is the hashCode function used by standard java implementation.
I was noticing unexpected delay in one of the operations related to double data
types.
After some debugging I realized that the HashMap puts and gets were extremely
slow.
That pointed me to the hashCode implementatoin in DoubleWritable which turned
out to be the cause of slow HashMap IO.
That is why I propose to use the standard java implmenetation of HashCode for
double type.
Thanks
Vaibhav
> Patch to fix hashCode method in DoubleWritable class
> ----------------------------------------------------
>
> Key: HIVE-1629
> URL: https://issues.apache.org/jira/browse/HIVE-1629
> Project: Hadoop Hive
> Issue Type: Bug
> Reporter: Vaibhav Aggarwal
> Attachments: HIVE-1629.patch
>
>
> A patch to fix the hashCode() method of DoubleWritable class of Hive.
> It prevents the HashMap (of type DoubleWritable) from behaving as LinkedList.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
