flaco 0.6.0rc1

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flaco

The easiest and perhaps most memory efficient way to get PostgreSQL data (more flavors to come?) into Arrow (IPC/Feather) or Parquet files.

If you're trying to load data directly into Pandas then you may find that evan a 'real' 100MB can cause bloat upwards of 1GB. Expanding this can cause significant bottle necks in processing data efficiently.

Since Arrow supports efficient and even larger-than-memory processing, as with dask, duckdb, or others. Just getting data onto disk is sometimes the hardest part; this aims to make that easier.

NOTE: This is still a WIP, and is purpose built for my needs. I intend to generalize it more to be useful towards a wider audience. Issues and pull requests welcome!

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Example

from flaco import read_sql_to_file, FileFormat


uri = "postgresql://postgres:postgres@localhost:5432/postgres"
stmt = "select * from my_big_table"

read_sql_to_file(uri, stmt, 'output.data', FileFormat.Parquet)

# Then with pandas...
import pandas as pd
df = pd.read_parquet('output.data')

# pyarrow... (memory mapped file, where potentially larger than memory)
import pyarrow as pa
with pa.memory_map('output.data', 'rb') as source:
  table = pa.ipc.open_file(source).read_all()  # mmap pyarrow.Table

# DuckDB...
import duckdb
cur = duckdb.connect()
cur.execute("select * from read_parquet('output.data')")

# Or anything else which works with Arrow and/or Parquet files

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License

Why did you choose such lax licensing? Could you change to a copy left license, please?

...just kidding, no one would ask that. This is dual licensed under Unlicense or MIT, at your discretion.