README.md

TsFile Python Document

Introduction

This directory contains the Python implementation of TsFile. The Python version is built on the CPP version and uses the Cython package to integrate TsFile's read and write capabilities into the Python environment. Users can read and write TsFile as easily as they use read_csv and write_csv in Pandas.

The source code can be found in the ./tsfile directory. Files ending with .pyx and .pyd are wrapper code written in Cython. The tsfile/tsfile.py defines some user interfaces. You can find some examples of reading and writing in the .examples/examples.py.

How to make contributions

Using pylint to check Python code is recommended. However, there is no suitable style checking tool for Cython code, and this part of the code should be consistent with the Python style required by pylint.

Feature List

• In pywrapper, invoke the batch reading interface implemented in CPP version of TsFile.
• Supports writing multiple DataFrames into one single TsFile.

Build

Before constructing Python version of TsFile, it is necessary to build CPP version of TsFile first, because Python version of TsFile relies on the shared library files provided by CPP version of TsFile.

Build by mvn in root directory:

mvn -P with-cpp,with-python clean verify

Build by python command:

python setup.py build_ext --inplace

File-level properties

TsFileWriter and TsFileTableWriter accept binary properties while they are open. The setter accepts bytes only. Readers return dict[str, bytes | None], preserving null and empty values separately.

with TsFileWriter("example.tsfile") as writer:
    writer.add_tsfile_property("binary-property", b"\x01\x00\xff")

with TsFileReader("example.tsfile") as reader:
    properties = reader.get_tsfile_properties()

Values do not carry a data type; use an explicit portable encoding when storing numbers or structures.

Local File Read Backend

Python readers inherit the process-wide backend setting when they open a file. PREAD is the default to preserve the traditional positioned-read behavior, MMAP requires memory mapping, and AUTO prefers mapping with a fallback to PREAD.

from tsfile import FileReadBackend, TsFileReader, set_file_read_backend

set_file_read_backend(FileReadBackend.MMAP)
with TsFileReader("example.tsfile") as reader:
    ...

# The configuration-dictionary API is equivalent.
from tsfile import set_tsfile_config
set_tsfile_config({"file_read_backend_": FileReadBackend.AUTO})

The setting only affects readers opened afterward. Do not modify or truncate a file while it is open through the memory-mapped backend.