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From "Jihong MA (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CARBONDATA-458) Improving carbon first time query performance
Date Mon, 28 Nov 2016 20:40:58 GMT

    [ https://issues.apache.org/jira/browse/CARBONDATA-458?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15703060#comment-15703060
] 

Jihong MA commented on CARBONDATA-458:
--------------------------------------

this work will contain materializing all file footer into a central fileļ¼Ÿplease describe
where this file will be stored under which directory? in what granularity(meaning would it
allows blocklet level or file level filtering at the driver side)? 

>  Improving carbon first time query performance
> ----------------------------------------------
>
>                 Key: CARBONDATA-458
>                 URL: https://issues.apache.org/jira/browse/CARBONDATA-458
>             Project: CarbonData
>          Issue Type: Improvement
>          Components: core, data-load, data-query
>            Reporter: kumar vishal
>            Assignee: kumar vishal
>
> Improving carbon first time query performance
> Reason:
> 1. As file system cache is cleared file reading will make it slower to read and cache
> 2. In first time query carbon will have to read the footer from file data file to form
the btree
> 3. Carbon reading more footer data than its required(data chunk)
> 4. There are lots of random seek is happening in carbon as column data(data page, rle,
inverted index) are not stored together.
> Solution: 
> 1. Improve block loading time. This can be done by removing data chunk from blockletInfo
and storing only offset and length of data chunk
> 2. compress presence meta bitset stored for null values for measure column using snappy

> 3. Store the metadata and data of a column together and read together this reduces random
seek and improve IO



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