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Date: Wed, 17 May 2017 01:57:04 +0000 (UTC)
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Subject: [jira] [Commented] (DRILL-5379) Set Hdfs Block Size based on
 Parquet Block Size
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archived-at: Wed, 17 May 2017 01:57:08 -0000


    [ https://issues.apache.org/jira/browse/DRILL-5379?page=3Dcom.atlassian=
.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=3D1601=
3380#comment-16013380 ]=20

ASF GitHub Bot commented on DRILL-5379:
---------------------------------------

Github user ppadma commented on a diff in the pull request:

    https://github.com/apache/drill/pull/826#discussion_r116895850
 =20
    --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/store/parq=
uet/ParquetRecordWriter.java ---
    @@ -380,14 +384,21 @@ public void endRecord() throws IOException {
    =20
           // since ParquetFileWriter will overwrite empty output file (app=
end is not supported)
           // we need to re-apply file permission
    -      parquetFileWriter =3D new ParquetFileWriter(conf, schema, path, =
ParquetFileWriter.Mode.OVERWRITE);
    +      if (useConfiguredBlockSize) {
    --- End diff --
   =20
    What we are doing is create parquet file as single block without changi=
ng the file system default block size.  For ex. default Parquet block size =
is 512MB and if file system block size is 128MB, we create single file with=
 4 blocks on filesystem, which can get distributed on different nodes, not =
good for performance. If we change Parquet block size to 128MB (to match wi=
th file system block size), for same amount of data, we end up creating 4 f=
iles, one block each, which is not good either.=20
   =20
    JIRA wanted single HDFS block per Parquet file that is larger than file=
 system block size , without changing file system block size.  They had fil=
e system block size configured as 128MB. Lowering parquet block size (from =
default value of 512MB) to match with file system block size is creating to=
o many files for them. For some other reasons, they are not able to change =
file system block size.=20


> Set Hdfs Block Size based on Parquet Block Size
> -----------------------------------------------
>
>                 Key: DRILL-5379
>                 URL: https://issues.apache.org/jira/browse/DRILL-5379
>             Project: Apache Drill
>          Issue Type: Improvement
>          Components: Storage - Parquet
>    Affects Versions: 1.9.0
>            Reporter: F M=C3=A9thot
>             Fix For: Future
>
>
> It seems there a way to force Drill to store CTAS generated parquet file =
as a single block when using HDFS. Java HDFS API allows to do that, files c=
ould be created with the Parquet block-size set in a session or system conf=
ig.
> Since it is ideal  to have single parquet file per hdfs block.
> Here is the HDFS API that allow to do that:
> http://archive.cloudera.com/cdh4/cdh/4/hadoop/api/org/apache/hadoop/fs/Fi=
leSystem.html#create(org.apache.hadoop.fs.Path,%20boolean,%20int,%20short,%=
20long)
> http://archive.cloudera.com/cdh4/cdh/4/hadoop/api/org/apache/hadoop/fs/Fi=
leSystem.html#create(org.apache.hadoop.fs.Path,%20boolean,%20int,%20short,%=
20long)
> Drill uses the hadoop ParquetFileWriter (https://github.com/Parquet/parqu=
et-mr/blob/master/parquet-hadoop/src/main/java/parquet/hadoop/ParquetFileWr=
iter.java).
> This is where the file creation occurs so it might be tricky.
> However, ParquetRecordWriter.java (https://github.com/apache/drill/blob/m=
aster/exec/java-exec/src/main/java/org/apache/drill/exec/store/parquet/Parq=
uetRecordWriter.java) in Drill creates the ParquetFileWriter with an hadoop=
 configuration object.
> something to explore: Could the block size be set as a property within th=
e Configuration object before passing it to ParquetFileWriter constructor?


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