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From Andries Engelbrecht <aengelbre...@maprtech.com>
Subject Re: Creating a single parquet or csv file using CTAS command?
Date Thu, 04 Feb 2016 18:31:10 GMT
You can create multiple parquet files and have the ability to query them all through the Drill
SQL interface with minimal overhead.

Creating a single 50GB parquet file is likely not be the best option for performance, perhaps
use Drill partitioning for the parquet files to speed up queries and reads in the future.
Although parquet should be more efficient that CSV to store data. You can still limit Drill
to a single thread to limit memory use for parquet CTAS and potentially number of files created.

A bit of experimentation may help to find the optimum config for your use case.


> On Feb 4, 2016, at 10:12 AM, Peder Jakobsen | gmail <pjakobsen@gmail.com> wrote:
> Sorry, bad typo:  I have 50GB of data, NOT 500GB  ;).  And I usually only
> query a 1 GB subset of this data using Drill.
> On Thu, Feb 4, 2016 at 1:04 PM, Peder Jakobsen | gmail <pjakobsen@gmail.com>
> wrote:
>> On Thu, Feb 4, 2016 at 11:15 AM, Andries Engelbrecht <
>> aengelbrecht@maprtech.com> wrote:
>>> Is there a reason to create a single file? Typically you may want more
>>> files to improve parallel operation on distributed systems like drill.
>> Good question.   I'm not actually using Drill for "big data".  In fact, I
>> never deal with "big data", and I'm unlikely to ever  do so.
>> But I do have 500 GB of CSV files spread across about 100 directories.
>> They are all part of the same dataset, but this is how it's been organized
>> by the government department who has released it as and Open Data dump
>> Drill saves me the hassle of having to stitch these files together using
>> python or awk. I love being able to just query the files using SQL (so far
>> it's slow though, I need to figure out why - 18 seconds for a simple query
>> is too much).   Data eventually needs to end up on the web to share it with
>> other people, and I use crossfilter.js and D3.js for presentation.  I need
>> fine grained control over online data presentation, and all BI tools I've
>> seen are terrible in this department, eg. Tableau.
>> So I need my data in a format that can be read by common web frameworks,
>> and that usually implies dealing with a single file that can be uploaded to
>> the web server.  No need for a database, since I'm just reading a few
>> columns from a big flat file.
>> I run my apps on a low cost virtual server. I don't have access to
>> java/virtualbox/MongoDB etc.  Nor do I think these things are necessary:
>> K.I.S.S
>> So this use case may be quite different from many of the more "corporate"
>> users, but Drill is so very useful regardless.

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