Laura

There isn't a way to limit the size of individual files. However, there might 
be a way you can get around this. 

One option is to serially convert each Parquet file into a CSV file separately. 
Typically, a fragment within Drill will generate this CSV file. That might 
generate 12 CSV files for each of the parquet files. 
If this doesn't work, you can use CTAS to generate smaller Parquet files from 
the existing Parquet files and then retry the previous step.

However, the simplest approach is to use some utility to split the files to a 
reasonable size. Linux has a utility called split. You should be able to find 
something similar on a Windows desktop too if that is the OS for Drill.

~ Kunal
On Tue 15-Nov-2016 8:44:23 AM, Mariano, Laura J. <[email protected]> wrote:
Hello all,

I have a large database of Parquet files that I need to convert to csv so they 
can be read into Matlab. (Unless someone knows how to do this automatically 
without an intermediate step?). I am using CTAS to create csv files from a 
directory of Parquet files, which works fine when the total size of the Parquet 
files is smallish (~= 800MB). In this case, CTAS will automatically generate 
about a few csv files, ~200 - 300MB each, which are easily digestible by Matlab.

However, I have a dataset consisting of 34 Parquet files, totaling 18GB. When I 
run CTAS on this to create the csv files using default parameters, it 
automatically generates 12 csv files, >2GB each. This is approaching the upper 
limit of what Matlab can handle, so I am wondering if there are any parameters 
I can set that will limit the size of the individual csv files that are 
automatically created by the CTAS process. i.e. is there a parameter equivalent 
to the store.parquet.block-size parameter for creating text files?

I am using Drill in embedded mode on a desktop.

Thanks!
Laura


Laura Mariano
Senior Member of the Technical Staff
Draper
[email protected]
(617) 258-2331

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