Example: Let’s say a table name user has id, name, email, phone, and is_active as attributes. And there are 1000s of users part of this table. I would like to read the details per user. void ParquetReaderPlus::read_next_row(long row_group_index, long local_row_num) { std::vector<int> columns_to_tabulate(this->total_row); for (int idx = 0; idx < this->total_row; idx++) columns_to_tabulate[idx] = idx; ..
Category : apache-arrow
Is it still the best answer in terms not coping data in memory? (What is the most efficient(fastest) way of passing data from C++ to Java?) I was thinking about Apache Arrow and I see two options: Building Apache Arrow data structure in C++, "serialising" it to bytes, passing bytes via JNI to Java class ..
I’m using conan to build a library that uses arrow parquet. I built arrow myself because I couldn’t find versions in conan center that included parquet: In my conanfile.txt [options] arrow:shared=True # I tried both shared and static arrow:parquet=True arrow:with_snappy=True conan install .. –build=arrow It builds and executes properly in my machine, but fails the ..
What is the best method to randomly access individual elements ("Scalars") of arrow::ChunkedArray e.g. for testing and display purposes? Is there some equivalent method to Array::GetScalar which takes into account that the ChunkedArray consists of multiple chunks? The way I found so far is an own helper function which "searches" the appropriate chunk like this ..
I got the idea of using pre-defined functions to do this: calculate "a + b", "c * 5", "d * 3" and then add the result. But this way seems generate a lot of code. Is there any better methods to do this? By the way, does Apache Arrow use SIMD by default(c++ version)? If ..
While reading the same feather file in python and in c++,in python, the function pyarrow.feather.read_table() performs expectionally well then the API i am using for c++. When i investigated further, i found out that the main difference is because in python the read_table() API uses a flag named, memory_map(set true by default). When i disable ..
Here is a cmake snippet that I use to link to libpqxx library that is installed by vcpkg and try to use the apache-arrow that is installed by brew. find_package(libpqxx REQUIRED) target_link_libraries(database PRIVATE libpqxx::pqxx) find_package(Arrow CONFIG REQUIRED PATHS /usr/local/lib/cmake/arrow NO_DEFAULT_PATH) find_package(Parquet CONFIG REQUIRED PATHS /usr/local/lib/cmake/arrow NO_DEFAULT_PATH) target_link_libraries(database PRIVATE arrow_shared parquet_shared) To run it I use: ..
Below is the solution that worked for me, but not sure if it is the best way to do this. I used brew to install it. vcpkg does not work at the moment, unfortunately. What I don’t like about this solution is that I need to set Parquet_DIR and find_package(Parquet) separately. set(Parquet_DIR /usr/local/lib/cmake/arrow) find_package(Arrow CONFIG ..
Recently, I have been working on a project in which we reads csv files, convert them to parquet and feather files and write them on disk. Also reading parquet and feather files is another feature we would like to have in the project. Now, I want to perform each and every single process described to ..
I have written code to read the same parquet file using c++ and using python. The time taken to read the file is much less for python than in c++, but as generally we know, execution in c++ is faster than in python. I have attached the code here – #include <arrow/api.h> #include <parquet/arrow/reader.h> #include ..
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