orc-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Xiening Dai <xndai....@live.com>
Subject Re: Questions about C++ interface
Date Thu, 01 Nov 2018 23:19:57 GMT
1) You can find the public headers in c++/include/orc. All the classes and methods have good
documentation in the code. You can also take a look at the sample c++ codes under tools/src,
especially FileContents.cc<http://FileContents.cc> and FileScan.cc<http://FileScan.cc>.
Both demonstrate the usage of c++ reader.

2) What you are mentioning is a feature we call “Predicate Pushdown”. Unfortunately it
is not supported by c++ reader currently. The java reader does support it through SearchArgument
class. I assume the implementation would be similar for c++ when we add this support in the
future.


On Nov 1, 2018, at 1:28 PM, Korry Douglas <korry@me.com.INVALID<mailto:korry@me.com.INVALID>>
wrote:

Hi all - I’m an absolute ORC newbie so please forgive the novice questions.

I’m trying to use the C++ API to implement a reader.  I have two questions (to start with):

1) I’ve been reading the docs at https://orc.apache.org/docs/core-cpp.html - is there more
complete documentation that describes all of the public classes that I can use?

2) My understanding is that an ORC file contains min/max indexes that can help me reduce the
amount of data I have to read to satisfy a given query.  Is there a class that I can use to
specify the range of values that I want to read?  Or do I have to read the statistics myself
(for each stripe?) and manually inspect the min/max values.

Thanks in advance.


            — Korry

Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message