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Posted to user@carbondata.apache.org by Liang Chen <ch...@apache.org> on 2017/05/13 09:13:39 UTC
Re: [jira] [Created] (CARBONDATA-1051) why sort_columns?
Hi Sehriff
Good question.
First, please check this doc:
http://carbondata.apache.org/useful-tips-on-carbondata.html, see if can
help you to understand CarbonData's index usage.
Like you mentioned that 1.2 will introduce sort columns feature to help
users to more easily specify which columns need to build index. for example
: "create table(c1...c7) tblproperties('sort_columns' = 'c7,c3')".
As you know , before 1.1 CarbonData by default builds MDK index as per the
order of columns in creation table, the feature will be kept in future
versions, so you can still use "create table (c1,c2,...c7")" to build
index.
HTH.
Regards
Liang
2017-05-13 13:55 GMT+08:00 sehriff (JIRA) <ji...@apache.org>:
> sehriff created CARBONDATA-1051:
> -----------------------------------
>
> Summary: why sort_columns?
> Key: CARBONDATA-1051
> URL: https://issues.apache.org/jira
> /browse/CARBONDATA-1051
> Project: CarbonData
> Issue Type: Improvement
> Reporter: sehriff
>
>
> since we already have many rmdb sqls scripts,we don't want to change them
> too much when migrating to carbon.
> suppose we already have sql script like:
> "create table (c1,c2,...c7")",
> If we want to change column order to shift most often used column ahead
> when query data,i think it's better change it this way like:
> "create table(c1,c2,c7,c4..c6,c3)
> rather
> "create table(c1...c7) tblproperties('sort_columns' = 'c7,c3')"
> because the former way just reordering columns without adding extra
> settings,which is more readable to thos who is familiar with rmdb but not
> with carbon.
>
>
>
> --
> This message was sent by Atlassian JIRA
> (v6.3.15#6346)
>
Fwd: [jira] [Created] (CARBONDATA-1051) why sort_columns?
Posted by Liang Chen <ch...@apache.org>.
---------- Forwarded message ----------
From: Liang Chen <ch...@apache.org>
Date: 2017-05-13 17:13 GMT+08:00
Subject: Re: [jira] [Created] (CARBONDATA-1051) why sort_columns?
To: dev@carbondata.apache.org, user@carbondata.apache.org, Sehriff <
1360496507@qq.com>
Hi Sehriff
Good question.
First, please check this doc: http://carbondata.apache.org/
useful-tips-on-carbondata.html, see if can help you to understand
CarbonData's index usage.
Like you mentioned that 1.2 will introduce sort columns feature to help
users to more easily specify which columns need to build index. for example
: "create table(c1...c7) tblproperties('sort_columns' = 'c7,c3')".
As you know , before 1.1 CarbonData by default builds MDK index as per the
order of columns in creation table, the feature will be kept in future
versions, so you can still use "create table (c1,c2,...c7")" to build
index.
HTH.
Regards
Liang
2017-05-13 13:55 GMT+08:00 sehriff (JIRA) <ji...@apache.org>:
> sehriff created CARBONDATA-1051:
> -----------------------------------
>
> Summary: why sort_columns?
> Key: CARBONDATA-1051
> URL: https://issues.apache.org/jira
> /browse/CARBONDATA-1051
> Project: CarbonData
> Issue Type: Improvement
> Reporter: sehriff
>
>
> since we already have many rmdb sqls scripts,we don't want to change them
> too much when migrating to carbon.
> suppose we already have sql script like:
> "create table (c1,c2,...c7")",
> If we want to change column order to shift most often used column ahead
> when query data,i think it's better change it this way like:
> "create table(c1,c2,c7,c4..c6,c3)
> rather
> "create table(c1...c7) tblproperties('sort_columns' = 'c7,c3')"
> because the former way just reordering columns without adding extra
> settings,which is more readable to thos who is familiar with rmdb but not
> with carbon.
>
>
>
> --
> This message was sent by Atlassian JIRA
> (v6.3.15#6346)
>