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https://issues.apache.org/jira/browse/SQOOP-2011?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14279760#comment-14279760
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Qian Xu edited comment on SQOOP-2011 at 1/16/15 3:17 AM:
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I propose SQOOP-1976, which will revert back to {{List<Column> getColumns()}}
(instead of having {{getColumnsList}} and {{getColumnsArray}}).
Here is the facts:
# If it's implementation is done with an ArrayList and the get operation is
O(1).
# If it's implementation is done with an LinkedList and the get operation is O(
n).
As IDF (and other classes) will read schema columns very frequently, choose
ArrayList as internal implementition is no doubt better than LinkedList.
If you think using array is better than ArrayList, do you agree we first
resolve SQOOP-1976?
was (Author: stanleyxu2005):
I propose SQOOP-1976, which will revert back to {{List<Column> getColumns()}}
(instead of having {{getColumnsList}} and {{getColumnsArray}}).
Here is the facts:
# If it's implementation is done with an ArrayList and the get operation is
O(1).
# If it's implementation is done with an LinkedList and the get operation is
O(n).
As IDF (and other classes) will read schema columns very frequently, choose
ArrayList as internal implementition is no doubt better than LinkedList.
If you think using array is better than ArrayList, do you agree we first
resolve SQOOP-1976?
> Schema should expose columns in array or list and not both
> ----------------------------------------------------------
>
> Key: SQOOP-2011
> URL: https://issues.apache.org/jira/browse/SQOOP-2011
> Project: Sqoop
> Issue Type: Sub-task
> Reporter: Veena Basavaraj
> Fix For: 2.0.0
>
>
> it is asking for trouble to store the schema columns in array and expose a
> list. the matching code currently uses LIST and it can completely use the
> array and work with it. In all places in IDF code we use the column array via
> the index.
> Array is preferred since it is easier to walk thorugh the object array
> format, there is one-one correspondence between the two with indexes
> http://eclipsesource.com/blogs/2014/04/11/3-good-reasons-to-avoid-arrays-in-java-interfaces/
> Please read the UPDATE section in the above link:) We really do not need the
> abilities of a list, we know the only reason we will use schema columns is
> read only.
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