GitHub user chunyang-wen opened a pull request:
https://github.com/apache/orc/pull/52
add support for nested column id selection, not only first level's id
Currently, orc c++ ReaderOptions only supports first level's id selection.
It is suitable for a flat data structure such as "struct<int1:int, d1:double,
t1:timestamp, d2:double>". The column id is: 0(root type), 1(int1), 2(d1),
3(t1), 4(d2). We can choose any combinations of 1,2,3,4.
But if orc file's schema has different levels of nested types, the include
function in ReaderOptions may not work properly. If the schema is
âstruct<int1:int, s1: struct<d1:double, t1:timestamp, d2:doulbe>>".
We can only select combination of 1(int1), 2(s1). Selecting other column id
will get an exception thrown.
In this patch, nested column id is supported. We can selected any column,
if one column is selected, its path to the root will also be selected in order
to create the reader.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/chunyang-wen/orc master
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/orc/pull/52.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #52
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commit 21ca200c35c21c2ea5a8bb8c395b44510343fa88
Author: wenchunyang <[email protected]>
Date: 2016-08-09T08:36:54Z
add support for nested column id selection, not only first level's id
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