Feature request: read a large DataFrame in chunks

[River-Shi]

Is your feature request related to a problem? Please describe.
If we have a really large dataframe that exceeds memory, and we need to process each part of it, parquet supports batch_size. I'm wondering if lib.read has similar functionality.

def read_parquet_in_batches(file_path, batch_size=10000):
    parquet_file = pq.ParquetFile(file_path)
    for batch in parquet_file.iter_batches(batch_size=batch_size):
        yield batch.to_pandas()

[DrNickClarke]

Hi. You can do this using the row_range argument of the read function.

We are planning various future improvements that will make this easier to use and faster.

[River-Shi]

Hi. You can do this using the row_range argument of the read function.

We are planning various future improvements that will make this easier to use and faster.

Yes, it can indeed be done using row_range or date_range，Can articdb implement a function like this, making it easier for users to operate on each batch instead of the entire dataframe, which would save a lot of memory?

def fetch_batch_from_arcticdb(
    symbol: str,
    start: str,
    end: str,
    batch_size: int = 1440,
    uri: str = 'lmdb://crypto_database.lmdb',
    library: str = 'binance',
):
    ac = adb.Arctic(uri)
    lib = ac[library]
    
    start_date = pd.Timestamp(start)
    end_date = pd.Timestamp(end)
    
    while start_date < end_date:
        batch_end = min(start_date + timedelta(minutes=batch_size), end_date)
        
        df = lib.read(symbol, date_range=(start_date, batch_end)).data
        
        yield df
        
        start_date = batch_end

[River-Shi]

Hi. You can do this using the row_range argument of the read function.

We are planning various future improvements that will make this easier to use and faster.

Hi, any new updates?

[vasil-pashov]

Hi. You can do this using the row_range argument of the read function.
We are planning various future improvements that will make this easier to use and faster.

Hi, any new updates?

Hi, the road map is not completely sorted out. @DrNickClarke will get back to you with more info.

[DrNickClarke]

Hi. Sorry for the delay coming back on this. Thank you for your suggestion. We definitely have plans to make chunking easier going forward. It has not reached the top of the priority list at this time but I hope you will be pleased to see the announcements we will be making in the near future.

[River-Shi]

Hi. Sorry for the delay coming back on this. Thank you for your suggestion. We definitely have plans to make chunking easier going forward. It has not reached the top of the priority list at this time but I hope you will be pleased to see the announcements we will be making in the near future.

I find some great features in dask. It would be great if arctic can implement it.

[DrNickClarke]

Hi. We managed to find time to add a basic chunking api. Here is the PR with the new api and tests. We would value your feedback.

#1853