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Date: Wed, 12 Jul 2017 21:50:00 +0000 (UTC)
From: "Jinfeng Ni (JIRA)" <jira@apache.org>
To: issues@drill.apache.org
Message-ID: <JIRA.13085018.1499302289000.233383.1499896200387@Atlassian.JIRA>
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References: <JIRA.13085018.1499302289000@Atlassian.JIRA> <JIRA.13085018.1499302289715@jira-lw-us.apache.org>
Subject: [jira] [Commented] (DRILL-5660) Drill 1.10 queries fail due to
 Parquet Metadata "corruption" from DRILL-3867
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archived-at: Wed, 12 Jul 2017 21:50:11 -0000


    [ https://issues.apache.org/jira/browse/DRILL-5660?page=3Dcom.atlassian=
.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=3D1608=
4777#comment-16084777 ]=20

Jinfeng Ni commented on DRILL-5660:
-----------------------------------

I thought you are asking for change to make Drill1.10 work with the new cre=
ated parquet metadata file on 1.11. However, from the last sentence, seems =
you are talking about to make sure staring from drill 1.11, it will work wi=
th any new future change. Did i miss anything here?

Also, from the Oracle example, where did you see that Oracle will fail with=
 an error if you run on top of a newer catalog? From the link, it's not cle=
ar to me.=20

> Drill 1.10 queries fail due to Parquet Metadata "corruption" from DRILL-3=
867
> -------------------------------------------------------------------------=
---
>
>                 Key: DRILL-5660
>                 URL: https://issues.apache.org/jira/browse/DRILL-5660
>             Project: Apache Drill
>          Issue Type: Bug
>    Affects Versions: 1.11.0
>            Reporter: Paul Rogers
>            Assignee: Vitalii Diravka
>             Fix For: 1.11.0
>
>
> Drill recently accepted a PR for the following bug:
> DRILL-3867: Store relative paths in metadata file
> This PR turned out to have a flaw which affects version compatibility.
> The DRILL-3867 PR changed the format of Parquet metadata files to store r=
elative paths. All Drill servers after that PR create files with relative p=
aths. But, the version number of the file is unchanged, so that older Drill=
bits don't know that they can't understand the file.
> Instead, if an older Drill tries to read the file, queries fail left and =
right. Drill will resolve the paths, but does so relative to the user's HDF=
S home directory, which is wrong.
> What should have happened is that we should have bumped the parquet metad=
ata file version number so that older Drillbits can=E2=80=99t read the file=
. This ticket requests that we do that.
> Now, one could argue that the lack of version number change is fine. Once=
 a user upgrades Drill, they won't use an old Drillbit. But, things are not=
 that simple:
> * A developer tests a branch based on a pre-DRILL-3867 build on a cluster=
 in which metadata files have been created by a post-DRILL-3867 build. (Thi=
s has already occurred multiple times in our shop.)
> * A user tries to upgrade to Drill 1.11, finds an issue, and needs to rol=
l back to Drill 1.10. Doing so will cause queries to fail due to seemingly-=
corrupt metadata files.
> * A user tries to do a rolling upgrade: running 1.11 on some servers, 1.1=
0 on others. Once a 1.11 server is installed, the metadata is updated ("cor=
rupted" from the perspective of 1.10) and queries fail.
> Standard practice in this scenario is to:
> * Bump the file version number when the file format changes, and
> * Software refuses to read files with a version newer than the software w=
as designed for.
> Of course, it is highly desirable that newer servers read old files, but =
that is not the issue here.


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