I think you meant MB (not GB) below. HDFS allows creation of very large files(theoretically, there is no limit). I am wondering why >2GB file is a problem. May be it is blockSize >2GB, that is not recommended.
Anyways, we should not let the user be able to set any value and later throw an error. I opened a PR to fix this. https://github.com/apache/drill/pull/852 Thanks, Padma On Jun 9, 2017, at 11:36 AM, Kunal Khatua <kkha...@mapr.com<mailto:kkha...@mapr.com>> wrote: The ideal size depends on what engine is consuming the parquet files (Drill, i'm guessing).... and the storage layer. For HDFS, which is usually 128-256GB, we recommend to bump it to about 512GB (with the underlying HDFS blocksize to match that). You'll probably need to experiment a little with different blocks sizes stored on S3 to see which works the best. <http://www.mapr.com/> ________________________________ From: Shuporno Choudhury <shuporno.choudh...@manthan.com<mailto:shuporno.choudh...@manthan.com>> Sent: Friday, June 9, 2017 11:23:37 AM To: user@drill.apache.org<mailto:user@drill.apache.org> Subject: Re: Increasing store.parquet.block-size Thanks for the information Kunal. After the conversion, the file size scales down to half if I use gzip compression. For a 10 GB gzipped csv source file, it becomes 5GB (2+2+1) parquet file (using gzip compression). So, if I have to make multiple parquet files, what block size would be optimal, if I have to read the file later? On 09-Jun-2017 11:28 PM, "Kunal Khatua" <kkha...@mapr.com<mailto:kkha...@mapr.com>> wrote: If you're storing this in S3... you might want to selectively read the files as well. I'm only speculating, but if you want to download the data, downloading as a queue of files might be more reliable than one massive file. Similarly, within AWS, it *might* be faster to have an EC2 instance access a couple of large Parquet files versus one massive Parquet file. Remember that when you create a large block size, Drill tries to write everything within a single row group for each. So there is no chance of parallelization of the read (i.e. reading parts in parallel). The defaults should work well for S3 as well, and with the compression (e.g. Snappy), you should get a reasonably smaller file size. With the current default settings... have you seen what Parquet file sizes you get with Drill when converting your 10GB CSV source files? ________________________________ From: Shuporno Choudhury <shuporno.choudh...@manthan.com<mailto:shuporno.choudh...@manthan.com>> Sent: Friday, June 9, 2017 10:50:06 AM To: user@drill.apache.org<mailto:user@drill.apache.org> Subject: Re: Increasing store.parquet.block-size Thanks Kunal for your insight. I am actually converting some .csv files and storing them in parquet format in s3, not in HDFS. The size of the individual .csv source files can be quite huge (around 10GB). So, is there a way to overcome this and create one parquet file or do I have to go ahead with multiple parquet files? On 09-Jun-2017 11:04 PM, "Kunal Khatua" <kkha...@mapr.com<mailto:kkha...@mapr.com>> wrote: Shuporno There are some interesting problems when using Parquet files > 2GB on HDFS. If I'm not mistaken, the HDFS APIs that allow you to read offsets (oddly enough) returns an int value. Large Parquet blocksize also means you'll end up having the file span across multiple HDFS blocks, and that would make reading of rowgroups inefficient. Is there a reason you want to create such a large parquet file? ~ Kunal ________________________________ From: Vitalii Diravka <vitalii.dira...@gmail.com<mailto:vitalii.dira...@gmail.com>> Sent: Friday, June 9, 2017 4:49:02 AM To: user@drill.apache.org<mailto:user@drill.apache.org> Subject: Re: Increasing store.parquet.block-size Khurram, DRILL-2478 is a good place holder for the LongValidator issue, it really works wrong. But other issue connected to impossibility to use long values for parquet block-size. This issue can be independent task or a sub-task of updating Drill project to a latest parquet library. Kind regards Vitalii On Fri, Jun 9, 2017 at 10:25 AM, Khurram Faraaz <kfar...@mapr.com<mailto:kfar...@mapr.com>> wrote: 1. DRILL-2478<https://issues.apache.org/jira/browse/DRILL-2478> is Open for this issue. 2. I have added more details into the comments. Thanks, Khurram ________________________________ From: Shuporno Choudhury <shuporno.choudh...@manthan.com<mailto:shuporno.choudh...@manthan.com>> Sent: Friday, June 9, 2017 12:48:41 PM To: user@drill.apache.org<mailto:user@drill.apache.org> Subject: Increasing store.parquet.block-size The max value that can be assigned to *store.parquet.block-size *is *2147483647*, as the value kind of this configuration parameter is LONG. This basically translates to 2GB of block size. How do I increase it to 3/4/5 GB ? Trying to set this parameter to a higher value using the following command actually succeeds : ALTER SYSTEM SET `store.parquet.block-size` = 4294967296; But when I try to run a query that uses this config, it throws the following error: Error: SYSTEM ERROR: NumberFormatException: For input string: "4294967296" So, is it possible to assign a higher value to this parameter? -- Regards, Shuporno Choudhury
