[jira] [Commented] (HBASE-16500) Do not add any store file on scanner reset that has a seq id greater than current read pt

["ramkrishna.s.vasudevan (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-16500?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15436660#comment-15436660 ] 

ramkrishna.s.vasudevan commented on HBASE-16500:
------------------------------------------------

The simplest way to solve this in in FileInfo record the lowest possible memstoreTS. So we have maxMemstoreTS in StoreFileREader now. Similarly we will have minMemstoreTS in that file. Compare the readPt with this minMemstoreTS and if the readPt is greater then don't include that file. 

> Do not add any store file on scanner reset that has a seq id greater than current read pt
> -----------------------------------------------------------------------------------------
>
>                 Key: HBASE-16500
>                 URL: https://issues.apache.org/jira/browse/HBASE-16500
>             Project: HBase
>          Issue Type: Improvement
>          Components: Performance, Scanners
>            Reporter: ramkrishna.s.vasudevan
>            Assignee: ramkrishna.s.vasudevan
>             Fix For: 2.0.0
>
>
> This in principle is similar to HBASE-15871. 
> Take for eg. we have a scanner created with read pt 4. After which a we do a lot of mutations and then flush the region. 
> Now when the scanner reset happens as part of the scan flow we tend to add the the newly flushed file also to the scanner heap and we keep scanning the file only to see that all the KVs are having an mvcc greater than the read pt 4. Ideally it is better to skip all of them and not add in the scanner heap. 



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