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https://issues.apache.org/jira/browse/ARROW-6985?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Casey updated ARROW-6985:
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Attachment: image-2019-10-25-14-54-32-583.png
> [Python] Steadily increasing time to load file using read_parquet
> -----------------------------------------------------------------
>
> Key: ARROW-6985
> URL: https://issues.apache.org/jira/browse/ARROW-6985
> Project: Apache Arrow
> Issue Type: Bug
> Components: Python
> Affects Versions: 0.13.0, 0.14.0, 0.15.0
> Reporter: Casey
> Priority: Minor
> Attachments: image-2019-10-25-14-52-46-165.png,
> image-2019-10-25-14-53-37-623.png, image-2019-10-25-14-54-32-583.png
>
>
> I've noticed that reading from parquet using pandas read_parquet function is
> taking steadily longer with each invocation. I've seen the other ticket about
> memory usage but I'm seeing no memory impact just steadily increasing read
> time until I restart the python session.
> Below is some code to reproduce my results. I notice it's particularly bad on
> wide matrices, especially using pyarrow==0.15.0
> {code:python}
> import pyarrow.parquet as pq
> import pyarrow as pa
> import pandas as pd
> import os
> import numpy as np
> import time
> file = "skinny_matrix.pq"
> if not os.path.isfile(file):
> mat = np.zeros((6000, 26000))
> mat.ravel()[::100] = np.random.randn(60 * 26000)
> df = pd.DataFrame(mat.T)
> table = pa.Table.from_pandas(df)
> pq.write_table(table, file)
> n_timings = 50
> timings = np.empty(n_timings)
> for i in range(n_timings):
> start = time.time()
> new_df = pd.read_parquet(file)
> end = time.time()
> timings[i] = end - start
> {code}
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