[
https://issues.apache.org/jira/browse/HBASE-12311?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14178748#comment-14178748
]
Lars Hofhansl commented on HBASE-12311:
---------------------------------------
Are there better/other ideas?
The core issue we want to get to: If a (re)seek would get us to a different
HFile block we should seek, otherwise repeated next()'s inside the block is
(far) more efficient. This decision would need to be made efficient - without
needing a bunch of compares of the row-key.
Tracking the maximum number of versions seen would a possible and relatively
cheap proxy to guess the likelihood of a seek getting us out of the current
block.
> Version stats in HFiles?
> ------------------------
>
> Key: HBASE-12311
> URL: https://issues.apache.org/jira/browse/HBASE-12311
> Project: HBase
> Issue Type: Brainstorming
> Reporter: Lars Hofhansl
>
> In HBASE-9778 I basically punted the decision on whether doing repeated
> scanner.next() called instead of the issueing (re)seeks to the user.
> I think we can do better.
> One way do that is maintain simple stats of what the maximum number of
> versions we've seen for any row/col combination and store these in the
> HFile's metadata (just like the timerange, oldest Put, etc).
> Then we estimate fairly accurately whether we have to expect lots of versions
> (i.e. seek between columns is better) or not (in which case we'd issue
> repeated next()'s).
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
